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Topic: Intermittent ABS light, 7-1 blink code (J1939 datalink), thoughts? (Read 5639 times) previous topic - next topic

Intermittent ABS light, 7-1 blink code (J1939 datalink), thoughts?

Towards the end of the trek from Nac to home, we started getting an intermittent ABS light (and click in the dash area).  Figured just a loose connection at the WABCO box or at a wheel sensor.

Info stored in the text file of VMSpc just says "unknown component", or something like that.  A past wheel sensor problem was identified correctly as "axle 3 left side sensor current low" so we know VMSPc should be able to ID common WABCO fault codes. 

Steve checked the blink codes and got 7-1 which is "Check for proper J1939 Data link connection (see wiring diagrams)".  Hmmm....  He removed/reattached the 5 connectors on the top of the WABCO ECU and the problem went away.  For a while.  Last turn before getting to the storage facility yesterday the light came back on.

In a photo (coach is in storage), we think we see what we think is the J1939 Data link connector just above the WABCO ECU (a grey-ish connector with 3 wires going to it).  Besides that, would there be any other locations we should check for connections?  Anything in the dash or the lower panel next to the driver? 

Any other thoughts on the issue?
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Intermittent ABS light, 7-1 blink code (J1939 datalink), thoughts?

Reply #1 –
Michelle,

My ProLink 9000 could do it but I don't have the correct cartridge. The cartridges are a dime a dozen for Hondas, Fords, etc. but at least $500 for your Meritor-Wabco system. The have a feature that lets them find intermittent faults. Here is a good pdf showing all the harnesses, etc as well as the diagnostic procedures. http://www.meritorwabco.com/MeritorWABCO_document/mm28.pdf The PDF shows all the connections, relays, fuses as well as a step by step procedure and only a digital multimeter is needed to be able to follow their instructions. Dave's suggestion of the electronic spray cleaner is good (Radio Shack).

Suggest you contact a fire dept and find out who they use to troubleshoot Meritor brakes as a most trucks don't use that system. A call to Meritor could also find the closest repair facility if you can't resolve it. Nexiq does make the cartridge for several models of ProLink readers/programmers.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Intermittent ABS light, 7-1 blink code (J1939 datalink), thoughts?

Reply #2 –
Quote from: Pierce & Gaylie Stewart –

Suggest you contact a fire dept and find out who they use to troubleshoot Meritor brakes as a most trucks don't use that system. A call to Meritor could also find the closest repair facility if you can't resolve it. Nexiq does make the cartridge for several models of ProLink readers/programmers.


Pierce,

We have the code (7-1) and know from the manual what it means (J1939 data link connection).  Given it's intermittent, we're thinking it's just a loose/corroded/dirty connection.  So it's a question of where do we look to check the data link connection?  Is it just that grey-bodied 3-wire connector (if our identification of it is correct) or are there other connections to check as well?  I figure there's good knowledge here on the forum for that; the truck shop probably doesn't have as much familiarity with where FT made their wiring connections (and their diagnostic fee is higher than Steve's when it comes to tracing wiring and checking/cleaning connections and hitting them with a little CorrosionX ;)  )

Michelle
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Intermittent ABS light, 7-1 blink code (J1939 datalink), thoughts?

Reply #3 –
Michelle,

On page 4 of the PDF, it has illustrations of all the components and their electrical connections. Think I would start there, pulling and spraying all the connections as the initial effort to keep the code from reappearing. If it reoccurs, a digital multimeter check would be in order. Probably a call to Foretravel would show where the ECU is mounted. Figure 1.1 on page 4 shows what it looks like so would one of the points to pull and clean the connections plus will identify it when you search for it. Just guessing but think it is probably cab mounted instead of chassis so I would look first close to the Allison ECU but have been wrong lots of times.

The advantages of a reader/programmer include the ability to record the event with hours, dates and length of time of the event occurrence.

Pierce

 
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Intermittent ABS light, 7-1 blink code (J1939 datalink), thoughts?

Reply #4 –
Quote from: Pierce & Gaylie Stewart –
On page 4 of the PDF, it has illustrations of all the components and their electrical connections. Think I would start there, pulling and spraying all the connections as the initial effort to keep the code from reappearing. If it reoccurs, a digital multimeter check would be in order.

Thanks Pierce.  I believe we have the D-version of the WABCO ABS (2 sets of blink codes, not 3).  I found the troubleshooting guide for it and put it in the files section.  I need to search for the Maintenance Manual for the D-version to see if there are DMM values.

ETA already had a copy of it, here it it is for others http://www.meritorwabco.com/MeritorWABCO_document/mm30.pdf
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Intermittent ABS light, 7-1 blink code (J1939 datalink), thoughts?

Reply #5 –
Is there a breaker (passenger side of the dash) opening with a regular pace??  If so, something is shorted and causing the breaker to open.  pc

S/W Houston 95" U320C SE/40' 
Build #4778  Cummins M11
Repairs & Covered RV Parking (BAO)
PPL is close..

Re: Intermittent ABS light, 7-1 blink code (J1939 datalink), thoughts?

Reply #6 –
Michelle, thanks for starting this thread. I hope you are making progress.
I have been browsing through the Merritor/Wabco literature; found nothing relating to your error code. But did find some interesting reference material, including a student manual and this Technical Bulletin about the interaction between the ABS & Retarders. It sure makes it sound as though the ABS wheel sensors will detect slippage and the ECU will cancel the retarder for the duration. The student manual also mentioned this and states "When the wheels are no longer locking, the retarder is automatically turned back on". I know this is a bit off topic, but wonder if anyone can verify this? Seems like it would make a difference when deciding whether to use or not use the retarder on wet road conditions..??
Dick, '03 U320 40' Tag, 2 slides, Coach #6075
Full Timers
2009 Honda CR-V

Re: Intermittent ABS light, 7-1 blink code (J1939 datalink), thoughts?

Reply #7 –
I was told not to use the retarder on wet slippery roads. I will use it in rain but anytime there isa possibility of cold wet I turn it off as I do in snow.  Got caught going to Florida last winter in feb in NC by snow. 
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Intermittent ABS light, 7-1 blink code (J1939 datalink), thoughts?

Reply #8 –
John, that agrees with my owners manual. I thought about including this quote from my manual  shortly after I made that post. "Using the retarder on wet or slippery roads can be like jamming on the brakes - your vehicle may slide out of control. To help avoid injury or property damage, turn the retarder enable to OFF when driving on wet or slippery roads." (Page 10-4 of my manual). My previous sob with an exhaust brake had the same kind of caution.
So . . . does this mean Foretravel choose not to implement the feature of the Wabco ABS that monitors the retarder for wheel lock-up or inappropriate sudden decreases in wheel rotation? Somehow that does not seem quite right to me. If the ability to control a transmission retarder is built into the Wabco Ecu, why wouldn't they use it? Ok, I ramble... ;)
I would like to know the answer, but personally I'm not willing to test it on icy roads! ;D
Michelle, sorry for hijacking this thread. I am interested in knowing the resolution to your issue.
Dick, '03 U320 40' Tag, 2 slides, Coach #6075
Full Timers
2009 Honda CR-V