J1939 terminating resistor test. There are only 4 pins you need to be aware of, which are: A Pin = J1708 Data Link + 6 days ago · I want to personally thank everyone who has donated to the forum recently. There should be (2) J1939 Extension Harnesses, MP92-1035, one in the Gauge Kit and one in the BOC Installation Kit. Let’s break it down into simple chunks so even if you’re not an electrical engineer, you’ll still walk away with a solid understanding of how this works. Verify correct resistor has been found by checking continuity from terminating resistor connection to 9-pin service connector. Repair: Replace the failed terminating resistor. Datalinks are about the most tricky to troubleshoot and test. For termination resistor locations refer to SS 3920 J1939 Terminating Resistor Locations - Cascadia Oct 27, 2020 · C7 and C9 Industrial Engines Troubleshooting – CAN Data Link – Test The CAN data link is used to communicate information between the Electronic Control Module (ECM) and other modules. In the upper right hand corner of the diagram is an alternate terminating resistor location. The electronic control units govern power distribution to the The document provides detailed information on J1939 datalink diagnostics, including terminology, wiring, symptoms of malfunction, and testing procedures for resistance and voltage. Aug 15, 2024 · Our overview of various CAN physical layers details which NI products support which & how to correctly terminate each layer. Replace the termination resistor if the range of resistance is not 114 Ohms to 126 Ohms. Those mega ohm readings your seeing are through the module boards. com Google Instead, follow the manufacturer's instructions to verify an electronically switched termination resistor is enabled (ex. for a display, verify the option is enabled in a settings menu). A good J1939 connection has aligned yellow and green wires (see image below). The wiring from the connector to each module is a HPV (medium duty) 1939 Troubleshooting Card Aug 29, 2022 · Cummins ISX11. s give a good overview of the data link. Apr 24, 2025 · In a key-off resistance test on a J1939 connector, a reading of 120 ohms suggests a missing terminating resistor, which is essential for proper CAN bus function. 3 Continue with step 5. Carefully remove the trim. 04 (Each) Aug 24, 2022 · (08-23-2022, 10:39 AM)Big_kevin_yqq Wrote: Never check resistance through data link with ecms powered up. Sep 30, 2019 · Originally Posted by Jpcoleman I think the offender is the taped connector along the lower frame 2 levels down from the disconnected reverse siren. 3. Not OK - Resistance is greater than 130 Ohms. For ABS communication issues on a 2012 Peterbilt MX13, check the terminating resistors on the J1939 CAN bus. I'm not getting any help at all from freightliner. 0 ohms - Short between CAN high and CAN low. It includes quick reference information, a 5 step process for pinpointing problems, frequently asked questions, and general repair procedures. Use the following table to determine if CAN + and CAN - have the correct voltage. If you experience intermittent data loss or fault codes, inspect the resistor terminals for corrosion or damage. Jul 7, 2012 · On vehicles with non-shielded J1939/15 cable, the terminating resistor outside the cab is identical to that used inside the cab and is located near the engine controller (with manual transmissions) or near the automatic transmission controller. May 7, 2024 · Vehicle-Specific Installation J1939 Connection The J1939 terminating resistor is located behind the instrument cluster. Test the voltage at the diagnostic connector between Plug in the unit you removed and repeat the steps removing the other unit containing terminating resistor, measuring the resistance between pins of the unit and the wiring, you already know which is the correct value range, don’t you? May 22, 2022 · Can anyone help me find the terminating resistor on the engine end of a 2007 XC-R freightliner chassis W/ OM 926 la engine. The test can be How to perform the test Locate a Diagnostic Link Connector (DLC), ECU, or terminating resistor connection to the J1939 network using the manufacturer wiring diagram. 4. 120 ohms - One terminating resistor is missing. On the private network, one resistor is integrated into the VGT actuator. However, that test won't reveal a short to ground. Use the worksheet below to identify which modules, connectors and terminals you have checked Connector Terminal Worksheet This can also help identify if the J1939_High and J1939_Low wires are pinned incorrectly at a connector Due to the many configurations and options available, the terminating resistor can be found in multiple locations Near the top of the transmission Left frame rail (could Aug 2, 2012 · In the upper portion of the wiring diagram, the J1939 backbone ends at the terminating resistor near the ABS ECU. CAN Bus Voltage Levels STEP 2 d CAN - will be tested separately. Jul 31, 2021 · 120 ohms means the other 120 ohm terminating resistor isn’t connected. Troubleshooting J1708 Issues Before we dive into how to troubleshoot the datalink, let’s take a look at the older 6 pin connector you’ll find on older J1708 only trucks. Two 120-ohm terminating resistors are connected in parallel on the data link, resulting in a total resistance of 60 ohms for a properly functioning data link. Updated the troubleshooting steps where resistance checks are performed. Click to expand The SAE J1939 communications network is developed for use in heavy-duty environments and suitable for use in horizontally integrated vehicle industries. When you measure the resistance between CAN HI to CAN LOW on a wiring harness you should measure 60 ohms. Install standard Deutsch DTM wedgelock in the Freightliner plug. That's where I usually find problems w/ datalink on volvo's I see. Termination resistors are required per the SAE specification. This procedure covers the 247-09 J1939 Data Link communications. I located the resistor under the dash above the brake pedal, but I'm unable to find the other end of the line resistor to test it. Study with Quizlet and memorize flashcards containing terms like The resistance of a terminating resistor used on a J1939 data backbone is _________. Jan 13, 2012 · The datalink terminating resistor is up near the fuse panel, under the fuse panel is where all the modules are. This is equivalent to the test I perform with Master Technicians on CAN Bus Technical Training!! I prefer to use an oscilloscope for my CAN Bus diagnostics (PicoScope 2204A), but my Fluke meter is The Controller Area Network (CAN) defined by SAE J1939 enables the integration of various vehicle components into an overall vehicle system by providing a standard way of exchanging information between these modules in the vehicle. The J1939 datalink consists of twisted yellow and green wires. Back tracking I check continuity from the terminating resistor connector to the cab connector and we're good. This supplemental troubleshooting guide is to provide additional information to the technical literature guides, and to offer some best practice guidelines to assist in diagnosing J1939 and CAN communication systems. Dec 2, 2020 · Termination Resistors A J1939 network requires a 120 ohms termination resistor at each end of the backbone (refer to Figure 1. Good news is that you have 120ohms with CECU conected it's a 2000$ cm, people usually have a problem @ CECU If you Jan 7, 2015 · The only problem I have here is that it says to unplug the EGR Valve connector and the J1939 termination resistor from the harness. Proceed to Test Step 4. The data link is quite simple on this engine: VGT, ECM, and terminating resistor, without any NOx sensors, temperature sensors, or others. Our setup is using the internal resistor on the MDL as the terminating resistor on one end of the network and has a standard 120 Ohm resistor wired into the other end. 3) . Result: The resistance is greater than 130 Ohms. If the terminating resistor comes out, pull it off and plug it back into the super seal connector. You cannot use a diagnostic tool to communicate with the private data link. 9 CM2250 – Service Manual 019-165 Data Link Circuit, SAE J1939 Aug 28, 2020 · The batteries are disconnected also. Locate the vehicle’s J1939 terminating It will connect to green and yellow wires labeled "J1939". The Glider-Link requires that the J1939 bus has proper terminating resistors installed. Wouldn't the circuit be at 60 ohms if the nox sensor was unplugged or bad? Check to see if you have 60-ohms at the J1939 connector for that circuit on the can buss wires with everything plugged in (and power off to everything). The wiring fro HPV (medium duty) 1939 Troubleshooting Card CAN + and CAN - will be tested separately. It ensures proper signal integrity by preventing signal reflections on the network. Measure between CAN High and CAN Low for approximately 60 ohms; higher values indicate wiring faults or poor terminations. May 24, 2022 · System Operation Description: The test steps that are described in this test can help solve the following problems. Aug 21, 2011 · My experience tells me there is a problem in the J1939 data link. Terminating Resistor T 3. Use the worksheet below to identify which modules, connectors and terminals you have checked Connector Terminal Worksheet This can also help identify if the J1939_High and J1939_Low wires are pinned incorrectly at a connector Due to the many configurations and options available, the terminating resistor can be found in multiple locations Near the top of the transmission Left frame rail (could Data Panel DP-34042-402 xtremeDB 4 Way J1939 Plug with 120 OHM Terminating Resistor is in stock and ready to ship same-day from Waytek! Dec 29, 2020 · Repair: If a termination resistor is missing, install the missing resistor. This skill allows me to ensure that the Controller Area Network is functioning properly, which means reliable communication between various components. Would it be right to think the CGW has an internal 120 ohm resistor & a 120 ohm end of line Resistor somewhere to terminate the J1939 CAN? How would you interpret the architecture diagrams? Apr 29, 2015 · J1939 Data Link Troubleshooting with a Calculator Why I use a calculator to troubleshoot a J1939 data link, yes I said a calculator. You will also not find any termination resistors on the backbone wiring. The terminating resistors should be at opposite ends of a data link circuit. Test the voltage at the diagnostic connector between pins A & C 2. Refer to the Schematic in order to determine the location of the missing resistor. I checked the resistance in the J1939 circuit, which showed 122. May 7, 2024 · This will give the installer access to the J1939 terminating resistor. Feb 12, 2019 · CANbus requires a 120 Ohm resistor at each end to 'terminate' the bus. There is a termination resistor located in the engine data link harness and another in the VGT actuator. Jul 7, 2015 · J1939 datalink terminating resistor location Discussion in ' International Forum ' started by hduane, Nov 11, 2018. What is the J1939 Data Link Diagnostic Tool? It is a tool that displays basic J1939 component information and J1939 voltage that can help trace J1939 malfunctions in the Cummins proprietary data link to a particular location in the harness and down to the exact wire. This guide is designed to assist in diagnosing potential issues with the J1939 Data Link. Therefore, option C, a missing terminating resistor is the Jul 15, 2018 · The Bus (+) circuit is grounded through another 13 kilohm resistor. Technician B says that most truck data backbones use electrical pressure of around 5 volts. 08/31/2015 - Added some general terminating resistor locations to the top of the "Diagnostic Steps" section. It will usually be a triangular Deutsch connector. Pin drag and whatnot in all the connectors. Jun 5, 2007 · Does anyone know if you need a 120ohm terminating resistor across the high and low GMLAN wires if you are programming a 6-speed TCM on the bench with Flashscan V2? Where are the 120ohm terminating resistors in the truck's wiring? Or are they all internal to the TCM/ECM/GPCM? Does the 01-05 dmax's J1939 CAN use any sort of terminating resistor For VGT actuator faults with stop engine lights, inspect the terminating resistor on the actuator harness side. The terminating resistor at one end of the J1939 data link is located in the Fuse/Relay Center near the VECU and the other near the engine ECU. The Delphi J1939 terminating resistor is an insert molded resistor end cap which mates to a sealed Delphi GT connection. 3 Continue with step 6. Refer to SAE J1939–11 for specific requirements. Use this procedure to troubleshoot any suspect problems with the CAN data link. The terminating resistor will be located in a large group of wires behind the radio. The next edition of Tech Talk will provide information about how to finish testing the J1939 by testing it for shorts to power and ground, and locating those shorts. Failed Resistors: A resistor may lose its specified 120-ohm value, leading to improper signal termination. If SPN 248/8 or 248/9 appears, proceed to Test Step 4. Faulty connectors Terminating resistors Short circuits Open… Use the worksheet below to identify which modules, connectors and terminals you have checked Connector Terminal Worksheet This can also help identify if the J1939_High and J1939_Low wires are pinned incorrectly at a connector Due to the many configurations and options available, the terminating resistor can be found in multiple locations Near the top of the transmission Left frame rail (could iRV2 Forums > THE CHASSIS CLUB FORUMS > Freightliner Motorhome Chassis Forum J1939 CAN Troubleshooting iRV2. If you had measured 120 ohms then one resistor is missing or there is some heavy corrosion in the connector to one of the resistors. This product provides a cost effective in-harness option for the CAN system. Well, that's partly thanks to the J1939 protocol and even more so to a little unsung hero known as the terminating resistor. Apr 22, 2025 · DL1 J1939 connector When using the DL1 J1939 connector, consider the following: If two ports are available, always use the one labeled DL1J1939. Oct 12, 2018 · 03/22/2018 ‐ Updated the printable PDF version that is linked below 03/21/2018 ‐ Updated service parts information to include non‐sheilded bulk data link cable 02/12/2018 ‐ Updated service parts information to include 3 pin and 2 pin terminating resistor part numbers, as well as mating connectors and terminals. Although the OEM resistor may be integrated into the wiring harness, check for damaged or corroded connectors causing open circuits. Study with Quizlet and memorize flashcards containing terms like What is the resistance of a terminating resistor used on J1939 data backbone?, Technician A says that there can be up to 2 open Tees on a J1939 data backbone. Proceed to Test Step 8. Remove the screws holding the top cover. Disassemble the Splice Pack . With the right equipment, checking termination on your CAN bus is relatively simple. The issue arises from a lack of communication on the J1939 data link between the engine ECM and the smart VGT controller. Unplug the end of the J1939 adapter. Freightliner cascadia 9 pin J1939 service data link plug and 3pin Cummins J1939 service data link location and what you should not do if your programming AT06-3S-RJ120BK, 3-Way, Plug, J1939-11, 120 Ohm Resistor, Gold Sockets, Blue Wedgelock, Black. Terminating resistors are used on J1939 to minimize a phenomenon called standing waves. Collision of reflected data can cause J1939 messages to be- come partially or completely lost Jan 16, 2018 · Each end of the bus should have a 120 ohm resistor, and since there should be only 2, their parallel resistance should be 60 ohms. This product provides a cost-effective in-harness option for the CAN system. I need help with j1939 communication issues on a 2012 kenworth, paccar mx13, eaton ultrashift. This will help show you the backbone of the data link (main data link wiring between 1st terminating resistor to 2nd terminating resistor) and the stubs of the data link (wiring from s and leave on 2 different terminals). A machine in the field is having CAN network issues. (B) Test Step 2: Check for Nodes Inspect the six-pin communication harness at the ECM: If wiring is present, go to Test Step 3. On vehicles equipped Volvo engines, the terminating resistor at the engine end is located inside the EECU. With all controllers powered off and both termination resistor in place, an ohmmeter should read 60 ohms across terminals A and B of the 3-way connector (refer to Figure 1. (08-23-2022, 10:39 AM)Big_kevin_yqq Wrote: Never check resistance through data link with ecms powered up. The J1939 terminating resistor is located behind the radio near the windshield. To troubleshoot, inspect the wiring harness ends near the ECU or gateway module for a 120-ohm resistor. If you can force the CAN bus to work at a very low speed (10 to 100 times slower than nominal) then maybe Aug 16, 2021 · The J1939 terminating resistor is located behind the radio near the windshield. There is a problem with the wiring harness between ECM 1 and the splice point into the data link wiring. Carefully remove the top cover. The yellow wire is J1939+; the green wire is J1939–. Terminating resistors, ECU communication tests, voltage tests, and circuit isolation are discussed as techniques for locating faults in the J1939 The J1939 data link enables high-speed communication between devices. 6. Note: The wiring for the J1939 data link is a shielded twisted-pair cable. Terminating Resistor f546394 sistor Located Behind the 4. I would say: very critical. Checking Voltages J1939/H1939 • To test the voltage the truck should be in the state of ignition ON, engine OFF, and batteries connected. 1 Test the J1939 backbone terminating resistance to verify that terminating resistors are installed and a complete circuit from the diagnostic connector through the J1939 backbone is established. With the battery connected, there should be a total of 5 volts in the J1939. The CAN bus is designed to be a 120 ohm system and it can only do so when all terminations are in place. Engine vin is #79735463 The J1939 terminating resistor is typically located at the end of the CAN bus wiring harness in the Freightliner M2 2016. Repair: Install the missing resistor. Install the terminating resistor wedge-lock in the DTM plug installed on the Momentum Y-Harness. If no wiring exists: Verify and/or replace the termination resistor (120 ohms). Sep 21, 2022 · STEP 2 d CAN - will be tested separately. The J1939 Control Data Link complies with SAE standards and consists of 2 twisted 2. The J1939 data link comprises a twisted pair of yellow and green wires that all modules on the truck utilize for communication. If one or more termination resistors are missing, communications may work temporarily but will be unreliable and eventually fail. Dec 2, 2020 · Vehicle-Specific Installation J1939 Connection 1. It helps pay for the $790/month internet bill that the forum consumes. , When using a DMM to measure voltage, which of the following should be selected to measure DC circuit voltage expected to be around 12 volts?, Which of the controllers is 'in charge' of managing data on a truck J1939 data bus? and more. I'm getting 61 ohms on Diagnosing J1939 data link issues involves checking CAN High and CAN Low wiring resistance, which should be around 60 ohms total. The Delphi J1939 Terminating Resistor is an insert molded resistor end cap which mates to a sealed Delphi GT connection. The physical layer aspects of SAE J1939 reflect its design goal for use in heavy-duty environments. Common Issues Missing Resistors: A missing termination resistor can cause an open circuit and disrupt communication. Repair: Determine the cause of the Jan 29, 2019 · And how critical it is/was that the bus was terminated at only one location, and at 120 ohm. It is in the shadow of the fuel line. Unlike the J1708 datalink, the J1939 datalink allows an ECU to broadcast requests as well as information. Examples of information that can be communicated on the J1939 datalink Dec 8, 2020 · With the battery disconnected, there should be 120 ohms across the high and low of the J1939. The J1939 data link has two 120 ohm resistors in parallel in the data link. If it is confirmed that the J1939 circuit is in fault, it must be taken to an authorized dealership for repairs. The other resistor is on the OEM side and should be mounted near the aftertreatment. I install the cab resistor and grab a 2nd tech to watch for a change in Ω while I wiggle the harness and we find it's back to 111Ω. This document provides guidance on diagnosing and troubleshooting issues with the J1939 datalink system. This will help show you the backbone of the data link (main data link wiring between 1st terminating resistor to 2nd terminating resistor) and the stubs of the data link (wiring from the backbone to each possible modu ). Study with Quizlet and memorize flashcards containing terms like J1939, Splitter Module, Terminating Resistor and more. This measurement should be conducted with the device power off. Horizontally integrated vehicles involve the integration of different combinations of loose package components, such as engines and 10. Jul 31, 2017 · Most modules are in sleep mode after 5 mins of key off. This resistance is made up of two 120 Ohm resistors. Feb 9, 2021 · The J1939 datalink is a high-speed vehicle datalink that communicates information between electronic control units (ECU) on the vehicle. 2. No Terminating Resistors: Unlike J1939, which requires 120-ohm Aptiv 15429045 GT 150 Series Connector, 2-way, J1939 Can-Bus 121 ohms Terminating Resistor is in stock and ready to ship. Here is what you need to do to know what you should be measuring at pins C and D for the J1939. 08/11/2015 - Provided specifications for terminating resistor. But, yes, can still test conventionally green to green and yellow to yellow end to end for broken or shorted wires. While at least one termination resistor is required for the system to operate, most Chrysler systems use two. Navistar engines have terminating resistors internal to the ECM and ACM Cummins engines have a terminating resistor internal to the VGT Actuator, and an external terminating resistor Cummins® test leads must be used in connection points to prevent damage to OEM connectors and terminals. If both resistors are present, measure the resistance between pin A and pin B of the termination resistor. Refer to the appropriate wiring diagram. The two resistors are known as "Terminating Resistors". 4V 1. These resistors ensure proper termination of the CAN bus network, preventing communication errors. This will help show you the backbone of the data link (main data link wiring between 1st terminating resistor to 2nd terminating resistor) and the stubs of the data link (wiring from the backbone to each ent terminals). Use a multimeter to test continuity across the resistor terminals. Similar to the diagram below: Bandwidth Test If the datalink shows good continuity - perform a load test to check the network bandwidth Apr 7, 2023 · Each of the two terminating resistor is 120 ohms. Sep 11, 2025 · When working with modern vehicles and machinery, understanding how to test CAN bus wiring with a multimeter is essential. I sent the CPC4 for repair, and the repair shop indicated it tested fine. Showing the thought process (mental digestion) of multiple fault codesShowing the mental direction of multiple fault codes and flow chart similarities and ab I suspect there may be a short to ground on the datalink, so if you test wire resistance, it should be fine for both the wires and the terminating resistor. I did read on another post that the ECM might contain the other other resistor, so pulling the plug at the ECM and getting 120 would be a good reading of the J1939 bus. STOP Test Step 5. The shape of the waveform changes slightly due to longer capacitance discharge times and increased signal reflections. Proceed to Test Step 3. Unscrew the trim from the dashboard. Use the worksheet below to identify which modules, connectors and terminals you have checked Connector Terminal Worksheet This can also help identify if the J1939_High and J1939_Low wires are pinned incorrectly at a connector Due to the many configurations and options available, the terminating resistor can be found in multiple locations Near the top of the transmission Left frame rail (could Our company uses an IQAN MDL2 setup which ties into the J1939 network of a Caterpillar system. - Thank you again. Not OK - Resistance is less than 50 Ohms. J1587 utilizes a two-wire bus for communication, and proper wiring and testing are more crucial than terminating resistors. In short, it is a multiplexing system that replaces traditional power distribution devices with ECUs that communicate electronically over the vehicle datalink. The wiring from the connector to each m Checking Resistance To test resistance on any of the CAN circuits the truck should be in a state of ignition OFF and batteries disconnected. The Cummins INLINE 7 adapter needs to be connected at the 3-pin service connector in order to successfully trace the Jan 31, 2025 · 2. Proper operation of the J1939 Vehicle Data Link is critical for proper transmission operation. Additionally, it emphasizes the importance of isolating sections of the circuit to identify ink. Well wiggle test didn't show a change. Ensure the vehicle's yellow and green cables align with the Motive's yellow and green cables. Jun 2, 2017 · This troubleshooting method will work for all truck makes but I will use a Freightliner Columbia in my example. 6V and 12. engines, the terminating resistor at the engine end is located inside the Engine ECU. It may be blue or black, but will appear as shown. enovationcontrols. If one of the resistors is missing, or a line is broken the tech will measure 120 ohms. Optimize your vehicle's electrical systems with Delphi‚Äôs space-saving GT 150 J1939 CAN-Bus Terminating Resistor, designed for rugged durability and waterproof performance. Working for a major fleet as a Technician Instructor I have Mar 12, 2025 · Learn everything about SAE J1939 network wiring and connectors, including cable specifications, pinouts, termination, and troubleshooting tips for reliable ECU communication in heavy-duty vehicles. J1939 issues on Volvo 2017 Volvo vnl D13 To my Volvo guys, truck came in in derate for scr, tried to hook up to it and can’t communicate with ecm or acm. Looking for help locating the terminating resistor on isx cummins single cam getting code 2636. In this quick video you’ll learn how to test the terminating resistor if communications between the IQ Gateway, IQ System Controller 3 or 3G, or IQ 5P Batter This symptom driven test is performed if the J1939 Vehicle Data Link is failing to function in some way without setting transmission Fault Code 115. Yes, that’s it. When the data link is in good condition the total resistance will be approximately 60 ohms on pins C and D of the 9 pin data link connector. It will separate into two pieces as shown below. When both are on the data bus, the tech will measure 60 ohms between data high and data low lines with the power turned off. A terminating resistor is missing. The wiring from the connector to each module is a st HPV (medium duty) 1939 Troubleshooting Card Load tested said wires, lights up no problem. Omitting a termination resistor results in reflecting signals. Route and install the VT harness and install the databus connections for vehicles built on 1/1/16, and later. Two 120 ohm resistors must be connected between J1939+ and J1939-, each one located at opposite physical ends of the bus. The resistor blades and mating terminal are gold plated to provide a reliable contact interface. This symptom driven test is performed if the J1939 Vehicle Data Link is failing to function in some way without setting transmission Fault Code 35. The DDEC-VCU connector pin assignments for SAE J1939 are listed in Table "J1939 DDEC-VCU to VIH Connector Pin Assignments" . Check the J1939 connection. When checking the J1939 on pins C and D make sure the ignition is Oct 19, 2015 · 2007 Freightliner Columbia J1939 terminating resister location? Discussion in ' Heavy Duty Diesel Truck Mechanics Forum ' started by Hulld, Jun 1, 2020. All 1939 will have a standard of about 60 ohms, including Volvo. Feb 27, 2020 · the data link. Order today! DT06-3S-P006, Plug, 3 Pin, Gray, 120 Ohms Terminating Resistor (J1939) Availability: In Stock $16. Turn the ignition key ON and put one test lead on ground and the other lead Use the following table to determine if CAN + and CAN - have the correct voltage. resistance on each terminating resistor. 3 fTS 1033683 : Checking and Testing J1939 and Diagnostic "Truck" CAN Networks Continuity Test If both resistance and voltage tests pass - check the continuity of the datalink using a basic continuity test. The terminating resistors should be at opposite ends of a data link circuit. Oct 27, 2021 · By Larry Turay, MACS contributor J1587/J1708 and J1939 data line diagnostics Modern heavy-duty equipment is basically comprised of computers with operating units attached. If the wiring is damaged, the replacement type must be shielded twisted-pair cable. There are few conditions as: 60 ohms - which states it's a good condition. com Note: For in-depth detail about the physical layer and termination resistors, we recommend more k. Turn the ignition key ON and put one test lead on ground and the other lead on CAN + (Pin C) or CAN - (Pin D). Important Note: Remember to check the resistance with the key in the off position. 5), or terminals C and D of the 9-way connector (refer to Figure 1. Check all the wiring between them. The J1939 communicates at 250,000 bits per second. View attachment 380660 The Delphi J1939 terminating resistor is an insert molded resistor end cap which mates to a sealed Delphi GT connection. The service lit says it has an internal 60 ohm resistor for terminating the Diagnostic CAN, but if you take measurements for the J1939 CAN you have various resistors in their architecture diagram. Nov 27, 2024 · If SPN 231/12 appears, proceed to Test Step 2. Connect a test lead to PicoScope Channel A and CAN H and its ground lead to battery negative or a good chassis ground. Always reinsert the terminating resistor into the other end of the Motive cable before you turn on the vehicle. Perfect for commercial and off-highway vehicles, it supports increased loads in CAN bus systems and meets SAE J1939 and ISO standards. I found the terminating resistor in the harness it tests good. NOTE: Battery condition is important and should be in the range of 12. 1 06/15/2016 1. Jan 14, 2021 · What exactly are you trying to do and explain the meaning of terminating resistors On most vehicles today the communication network for the modules is a J1939 CAN (controller area network) This circuit has a 5 volt signal on each leg of the circuit. It outlines the components involved, diagnostic connector pin descriptions, and methods to locate shorts in the circuit. Termination Resistor Failures Termination resistors are critical for maintaining the integrity of the CAN signal. 6). STEP 2 d CAN - will be tested separately. When using a DMM to perform a key off resistance test across terminal designations D and C on a J1939 diagnostic connector, a reading is observed to be as 120 Ohms. Use of a J1939 network, or datalink, for on-vehicle communication can greatly reduce the amount of wiring in a vehicle, and give many different components and Additional troubleshooting tips and resources here: https://support. Any J1939 network will have two terminating resistors. A terminating resistor is used to stabilize the voltage between the two (2) circuits. Aug 2, 2012 · This test checks whether or not both terminating resistors are installed, and ensures that there is a complete circuit from the diagnostic connector through the backbone loop. The J1939 datalink has two terminating resistors, one at each end of the backbone. Faulty or missing resistors cause signal loss between the ABS and other modules. Also use this procedure if a diagnostic code in Table 1 is active or easily repeated. Note: The wiring for a J1939 data link is a shielded twisted-pair cable. The J1939 resistors in a 2009 Cascadia are typically located within the engine ECM wiring harness or near the diagnostic connector. Jul 18, 2019 · J1939 cable is required for the J1939 data link. Experience has shown that if only one J1939 terminating resistor is missing, the vehicle will likely not exhibit any observable symptoms. Have you made sure you are measuring resistance across the correct pins on your diagnostic connector? Plug the remaining J1939 connector on the Volvo diagnostic backbone harness into the location from where you removed the termination resistor at point 3 above (see yellow arrow in image above). This will help show you the backbone of the data link (main data link wiring between 1st terminating resistor to 2nd terminating resistor) and the legs of the data link (wiring from the backbone to each possible mo ls). 1 07/01/2016 f546410 1. Mar 29, 2025 · J1587 In J1587/J1708 networks, terminating resistors are generally not required, unlike J1939 networks. Who is correct?, On a truck data bus, how many wires are used to broadcast J1939 Use the worksheet below to identify which modules, connectors and terminals you have checked Connector Terminal Worksheet This can also help identify if the J1939_High and J1939_Low wires are pinned incorrectly at a connector Due to the many configurations and options available, the terminating resistor can be found in multiple locations (250k only vehicles) Near the top of the transmission in Discover our J1939 connector solutions, a Controller Area Network system designed for the automotive and diesel engine industries. Comparable to PN# DT06-3S-EP10, DT06-3S-PP01-AT06-3S-RJ A resistance reading around 120 mayindicate a missing terminating resistor or an open circuit somewhere in the readings may indicate an open circuit or a short 1 Quick Test #1: Check Resistance of the J1939 Datalink Across Pins C and D at the Diagnostic ConnectorQuick Test #2: Check ECU communication on J1939 using the J1939 Datalink : The Plug the remaining J1939 connector on the Volvo diagnostic backbone harness into the location from where you removed the termination resistor at point 3 above (see yellow arrow in image above). Proper communication requires 60 ohms resistance between the CAN_H and CAN_L lines, achieved by two 120-ohm terminating resistors at each end of the network. If this resistance is not present, then the data will be intermittent or unreadable. Overview This symptom driven test is performed if the J1939 Vehicle Data Link is failing to function in some way without setting transmission Fault Code 35. Gold-plated female terminals are also available for enhanced connectivity. I got the EGR valve, but I don't know where the termination resistor would be. Aug 27, 2025 · CAN Bus Termination There should be a 120-ohm termination resistor located at each end of the bus to prevent signal reflections. Oct 19, 2020 · C13, C15, and C18 Engines Troubleshooting – Data Link – Test System Operation Description: Use this procedure to troubleshoot the electrical system if a problem is suspected with the CAN data link or the Cat Data Link. Disconnect the Modules and Check for Communication Aug 23, 2022 · I appreciate ur you replying! I will go in morning check/perform this. Oct 7, 2022 · Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts. The purpose of the terminating resistors is to mini- mize the reflection of data on the datalink. Plug the remaining J1939 connector on the universal diagnostic backbone harness into the location from where you removed the termination resistor at point 2 above (see orange arrow in image below). Each resistor will have a resistance value of 120ohms. The second termination resistor serves as a backup and it's located in the PCM. 5. Install the Y harness to the Freightliner Plug and terminating resistor. Key off for terminating resistor checks I’m gettin Those Megohms when it’s completely powered down. xkibwk rfkc wiof knwbz brsw zotfr wptwm pkmv hzy seak