2004 ZF freedom line Auto trans + abs ECU J1939, been in several shops

Hoping someone can help me get this truck I own fixed 2004 VN day cab D12 engine ZF FREEDOM LINE AUTO . It has been at several dealers over the course of 3 years an ongoing intermittent condition. At times the trans will disable auto shift and go into only manual mode. The dash displays in the tcu J1939 intermittently. It only sets when shifted into forward or reverse. It does not appear when the truck is running and in neutral. I can clear the code and it stays away till the auto shifter is used. I am curious as to the FMI 14? (special instructions) what does this mean exactly??

The ABS ECU is a wabco system with traction control. It was also setting the J1939. this code would very seldom clear and stay cleared. Occasionally I do get at LH 2nd axle wheel speed sensor fault(very rare)

I have checked the CAN System thoroughly wiggle tested, located and inspected the through cab connector there is also a CAN harness connector at the trans that was easily spotted.
I have never had a bad reading on the CAN system 2.6volts and 2.4volts when running or key on. 59.8ohms resistance key off.

Today I wiggle tested around the ABS ecu. and checked my CAN wires at the module (which tested normal) same as anyplace else on the CAN network. I checked power and ground are also ok to the module. After reconnecting the abs ECU I can not get any info to the dash display from the module. OPERATION FAILED. is all that i get when trying to get codes from the abs. (connectors are secure and correctly located) I also continue to get the TCU J1939 MALFUNCTION code. The TCU throws the code consistently every time the shifter is shifted out of neutral this condition is no long intermittent but ACTIVE. This was an intermittent problem before I touched the ABS ECU.

Does the J1708 data link system use the same kind of voltage tests as a CAN network? I am curious because I have 1.4volts and 3.6volts? Which if this was a CAN system there would be a fault in the system. But this datalink does not set any DTC's? OR is J1939 set if the J1708 system fails as well???

Help please we need this truck working to get our harvest off.

 

Thanks Palbo. this is very good helpful information. I have 1.2kohms resistance on all abs wheel speed sensors. But like I said it does randomly set at LH 2nd axle code. This truck has had the ABS harnesses lengthened to the rear speed sensors as the frame was lengthened and a 20ft box installed. I have tried swapping the 3rd axle wiring to the LH end axle sensor and when the code would set for a bad wheel speed sensor it would from process of elimination still point to a faulty sensor on the 2nd axle left side.

Now I am very familiar with the ABS harness wiring being twisted just like a CAN harness from the factory (I have several years experience in the automotive repair field). None of the ABS wires where lengthened using twisted wiring. Maybe there is some interference in the system as well from this. I will rewire the sensors using the correct wiring using twisted/shielded wire when I replace the sensor, and hope for the best. THOUGHTS?

And Qualitytruck yes I was certain to check that the pins stay in the duetch connectors properly when seated, That is one fault of those connectors as that is a common problem with pins backing out..

 

PABLO-US you hit the nail on the head. I still do not understand why every single volvo dealer within 1000miles said the Data line was bad as per the J1939 DTCs.

But I did find the reluctor ring had slipped out of alignment on the 2nd axle LHS and the sensor was out of adjustment. Replaced the sensor, got the reluctor reinstalled with zero run. Also found I never had one connector fully seated on the Wabco ABS module that corrected the no communication problem I caused, but the incorrect sensor data was the culprit.

A $50 part corrected $20,000 worth of repairs at different Volvo dealers that they could not diagnose properly. The transmission and TCU were both overhauled the first time the truck went in for this concern..Unbeliveable that trained factory technicians at the dealer miss diagnosed this problem from day one and the customer was able to fix the problem all because of this forum. I cannot Thank You enough