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trucktech
16th January, 2011, 08:23 PM
I have a guide that is simple to understand and is a lifesaver for J1939 Faults, such as those that are constantly seen and are generally inactive and no one usually worries about. :dancing2:

mondao
16th January, 2011, 09:09 PM
Can you share your information with us, thanks

trucktech
16th January, 2011, 10:44 PM
Download & print out because you will need this, it's one of the best tricks I have ever learned.

zandokan
19th February, 2011, 05:39 AM
Thanks for posting the info. Data-links can be tricky to troubleshoot at times :puke:

bekamon
19th February, 2011, 08:11 AM
gracias por su contribucion , este problemas es muy comun , al no saber esto ,perdemos tiempo y dinero

thanks

hercamp
20th February, 2011, 03:12 AM
is cool....but what is tjis for? or what is it?

zandokan
20th February, 2011, 03:51 AM
The J1939 datalink is a high-speed vehicle datalink
that communicates information between electronic
control units (ECU) on the vehicle. The J1939 communicates
at 250,000 bits per second.
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

hercamp
20th February, 2011, 04:07 AM
I know what data link is..and what is on bus comms..but I mean what is this folder posted to do???

zandokan
20th February, 2011, 04:16 AM
Why I use a multi-meter and a calculator to troubleshoot a J1939 data link, yes I said a calculator. Working for a major fleet as a Corporate Technician Instructor I have taught many courses. I have to teach everything from bumper to bumper and that could be 3 axle alignments to troubleshooting a data link. One of the most valuable things I will teach technicians is how to use a calculator to troubleshoot the J1939 in my Advanced Data Link Course.

What I am going to share with you about the J1939 data link is life experience versus text book. Let me explain: Modern day trucks have multiple data links used by all the modules. The most common one used is the high speed J1939. Trucks will come into the shops all the time with inactive codes for data links, ABS J1939 time outs, and Engine ECU?s data link failures and so on. Most of the time these codes will get erased and no troubleshooting will be done. I will tell you how to find the possible problem.
This troubleshooting will work for all truck makes but I will use a Freightliner Columbia in my examples. The J1939 data link has two 120 ohm resistors in parallel in the data link. 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.

Locations of the 2 resistors on some different trucks:
Freightliner Columbia: R1 left hand frame rail, front cab mount and R2 right hand frame rail near frame mount ABS module
Freightliner Century Class: R1 left hand frame rail, front cab mount and R2 left hand B pillar
Volvo with Cummins Power: R1 near engine ECM connector and R2 cab fuse panel
Volvo with Volvo Power: R1 built into engine ECM and R2 cab fuse panel
IHC ProStar: R1 left hand frame rail strapped to airlines near transmission and R2 strapped on top of transmission towards the rear

Before I get into actual troubleshooting you will need to understand how to calculate the resistance in the J1939 harness. Here is the simplest formula and you will need your calculator.
Product over sum
R1xR2
R1+R2

120x120 = 14400
120+120 = 240

14400/240 = 60 ohms


I see all the time inactive codes in the ABS for J1939 time outs on Freightliner Columbia. In about a 3 month period I can count at least 15 trucks that I had to walk someone through these diagnostic steps to find the problem. When checking the J1939 on pins C and D make sure the ignition is off and no modules are communicating when you check the resistance.

The trucks that were checked had measurements that were about 64 to 68 ohms. In most data link troubleshooting text books this is an acceptable measurement and falls within the 60 ohms + or - 10 ohms. My experience tells me there is a problem in the J1939 data link. 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.

Here is what you need to do to know what you should be measuring at pins C and D for the J1939. Note: these were actual measurement on a truck that had a problem
1. remove resistor 1 out of the harness and measure it, lets say it measures 118 ohms
2. remove resistor 2 out of the harness and measure it, lets say it measures 119 ohms
3. Plug these resistances into your formula to know what the actual measurement at pins C and D should be.

118x119 = 14042
118+119 = 237

14042/237 = 59.24 ohms

As you can see we should measure approximately 59 ohms on this data link you can add a small amount for the resistance in the wires but should still be very close to 59 ohms. In everyone of these Columbia?s the resistor near the ABS module on the right hand frame had some green corrosion in the 3 way connector that holds the resistor. Seems the o-rings that should seal out the moisture do a better job sealing in the moisture that got inside of it. After cleaning up the corrosion in the connector the resistance measurement on pins C and D of the J1939 connector dropped from 68 ohms to 59 ohms.

I have used this diagnostic method on many trucks: Volvo, ProStar and Freightliner. I would practice this on a good truck and you will see that using a calculator to calculate the resistance should match what your multi-meter shows you. You will repair many data link problems if you learn this method.

Note: There are some trucks that the J1939 data link resistance can?t be measured unless the batteries are disconnected. IHC ProStar recommends it but I have checked the data link without disconnecting the batteries. Freightliner M2 and C2 chassis you must disconnect the batteries to check the J1939. These trucks and/or school busses have bulk head and chassis module that communicate all the time even with the ignition off and the data link can?t be checked as long as module are transferring data on the J1939.

zandokan
20th February, 2011, 04:21 AM
:hmmmm2:that's what the file says

hercamp
20th February, 2011, 04:28 AM
very enteresting.....thank you very much.....Ive seen a lot of volvo vnls with that data link problems ....and get that resistance brokend..good thread

dimitar22
21st February, 2011, 07:05 PM
Thanks very useful info.

alsop
11th June, 2011, 04:17 AM
Here is a link for a power point J1939 training. It is worth the download.

https://www.rapidshare.com/files/3188109646/2005_SAE_J1939_Training_.rar

ddmech
14th October, 2011, 03:47 AM
Been working on some j1939.Info has helped a lot.Thanks guys.

alsop
15th October, 2011, 12:29 AM
One of the most common problems I have found with a complaint the speedometer and some gauges drop out is loss of communications. The best program for diagnosing is included with Insite 7.2. Cummins fault viewer will show the J1939 fault.
Most of the time it ends up being the deutch T splitter is going bad near the ECM. It will split off for abs and trans to vehicle and might have the 120 ohm resistor in one part.
The attached jpg is a harness I made for diagnosing a bad splitter.

joes108
27th October, 2011, 04:57 PM
Here is a J1939 Troubleshooting diag PDF for the International Prostar

rudamie
30th October, 2011, 10:36 PM
Thanks fellow DK's excellent contribution

techbahi
18th August, 2012, 09:05 AM
Bonjour je suis un formateur qui veut une formation sur la J1939/J1587 je suis ? votre service contacter moi
(NO ADDYS :rulez:)

Shaggy76
2nd September, 2013, 05:03 PM
Here is a link for a power point J1939 training. It is worth the download.

https://www.rapidshare.com/files/3188109646/2005_SAE_J1939_Training_.rar

This link is dead. Can I get it reuploaded? I am cusrious to troubelshooting these connectors.

Everyone else, thanks for the info! It will help me a lot! I have many vehicles with these issues that come in and I am lost on what to do to diagnose them.

jackalfa
29th September, 2013, 02:01 AM
Please members I need your help again, I'm trying to find the terminating resistors in a peterbilt 386 2011 with CM2250 ISX XTA15-E10, I found one in the engine side in a blue connector but I can find the other one which should be somewhere in the frame rail or ??
J1939 Troubleshooting Card for Peterbilt would be handy.
I have a fault 3232 Aftertreatment Intake NOx Sensor - Abnormal Update Rate. No communication or an invalid data transfer rate has been detected on the J1939 data link between the ECM and the aftertreatment intake NOx sensor.
There is voltage or power from the battery (ignition) and a new sensor was installed already but still the same fault.

Any help will be greatly appreciated...

mondao
29th September, 2013, 04:05 AM
Please members I need your help again, I'm trying to find the terminating resistors in a peterbilt 386 2011 with CM2250 ISX XTA15-E10, I found one in the engine side in a blue connector but I can find the other one which should be somewhere in the frame rail or ??
J1939 Troubleshooting Card for Peterbilt would be handy.
I have a fault 3232 Aftertreatment Intake NOx Sensor - Abnormal Update Rate. No communication or an invalid data transfer rate has been detected on the J1939 data link between the ECM and the aftertreatment intake NOx sensor.
There is voltage or power from the battery (ignition) and a new sensor was installed already but still the same fault.

Any help will be greatly appreciated...
here http://www.peterbilt.com/resources/Peterbilt%20Body%20Builder%20Manuals/Peterbilt%20Body%20Builder%20Manuals_Peterbilt%20H eavy%20Duty%20Body%20Builder%20Manual.pdf

Elfer
22nd November, 2013, 12:30 PM
Thank you all a very helpful thread

cholmes729
22nd November, 2013, 08:29 PM
Let me try to teach a little more on J1939 issues. I work on Freightliner trucks daily, so my experiance is on Freightliners pretty much.

The split loom on Freightliner trucks is a very common problem of most of the wiring issues that occur on these trucks, especially J1939 problems. Look for a green stripe on the loom. It is notorious for cutting into the wiriing, and can cut the wiring in half. Look for sharp bends and tight zip ties, also tight wiring clamps.

As far as J1939 tips. Take your multimeter leads, and put them on the Diagnostic connector, start pulling and tugging on these areas and see if your meter goes OL or changes resistance. This will help you narrow down a possible location of the problem.

If you have a J1939 issue, and you want to see if the datalink is locked up because of an ECM. Go into your Nexiq device tester, change it to J1939 and see if anything is scrolling data. If it is not scrolling data. Start unplugging each ECM one at a time that is connected to the J1939 datalink till you get scrolling data. Qual-Comms are most of the issues, but ABS modules have caused it too. If the customer does not have a qual-comm, or it has been removed. Look at the connector that plugs into the satellite at the top of the cab. If the qual-comm wiring was not removed correctly, You will find that it will be corroded because it is open to the outside elements. This can cause the datalink to act up, as well as short out the B-pillar PDM behind the driver seat. The DIAG/OPT circuit breaker is typically tied into the power for the satellite.

If all else fails, and you cannot locate the open in the J1939 wiring to a certain component, make a new twisted pair of wires and run it outside of the existing harness. Be sure to add the terminating resistor.

Roy Suryadwiananda
23rd November, 2013, 02:53 AM
Let me try to teach a little more on J1939 issues. I work on Freightliner trucks daily, so my experiance is on Freightliners pretty much.

The split loom on Freightliner trucks is a very common problem of most of the wiring issues that occur on these trucks, especially J1939 problems. Look for a green stripe on the loom. It is notorious for cutting into the wiriing, and can cut the wiring in half. Look for sharp bends and tight zip ties, also tight wiring clamps.

As far as J1939 tips. Take your multimeter leads, and put them on the Diagnostic connector, start pulling and tugging on these areas and see if your meter goes OL or changes resistance. This will help you narrow down a possible location of the problem.

If you have a J1939 issue, and you want to see if the datalink is locked up because of an ECM. Go into your Nexiq device tester, change it to J1939 and see if anything is scrolling data. If it is not scrolling data. Start unplugging each ECM one at a time that is connected to the J1939 datalink till you get scrolling data. Qual-Comms are most of the issues, but ABS modules have caused it too. If the customer does not have a qual-comm, or it has been removed. Look at the connector that plugs into the satellite at the top of the cab. If the qual-comm wiring was not removed correctly, You will find that it will be corroded because it is open to the outside elements. This can cause the datalink to act up, as well as short out the B-pillar PDM behind the driver seat. The DIAG/OPT circuit breaker is typically tied into the power for the satellite.

If all else fails, and you cannot locate the open in the J1939 wiring to a certain component, make a new twisted pair of wires and run it outside of the existing harness. Be sure to add the terminating resistor.

Good experience.