2007 Bluebird Vision/ Engine Comm Failure, Trans Comm Failure, ABS Comm Failure

[MrZapzy]

I have a 2007 Bluebird Vision with a C7 Acert engine and Allison transmission.

When I turn the key to the run position (without starting) the speedometer reads engine comm failure, trans comm failure, and ABS comm failure. All of the gauges start sweeping. The bus can be started, however the problem persists.

This occurred infrequently at first, now it happens everytime I try to start the bus. I have tried another speedometer after reading it is the "master gauge". It did not solve the problem however it was a used part.

Any help would be greatly appreciated

[CHEESE_WAGON]

Based on what a few other members have had to say about similar situations, I think you need to be looking for a blown fuse / fusible link, bad circuit breaker / relay, or possibly a burned or loose wire.

[MrZapzy]

Okay we will check those out. If you or anyone thinks of another possible cause I would appreciate the help. I've seen others even say replacing some of the slave gauges can fix it but I'm unsure if that would be the case.

[cadillackid]

thje J1939 network is going down.. im an IH giuy so I dont have the resurces for these however what you describe sounds like the J1939 data comms is shorting out.. there is a 2 wire twisted pair of wires that goes to the trans / ABS / Dash / ECM and I think these have a BCM.

this is new enough you may be able to log onto bluebird vantage and download the wiring diagrams for this..

my vote is that a connector has gotten water / corrosion in it and is shorting down the network..


an open wire in the network would drop only one device.. a fuse blow would be a constant down all the time. (unless its a circuit breaker trip.. but since the bus does start we know the ECM has power or the engine wouldnt run)...

-Christopher

[Booyah45828]

The visions had issues with the fuse holders at the multiplex being loose/corroded and causing this.

I saw once where a failed coolant level sensor pushed coolant through the wire and into the sealed connector of the ecm, which caused corrosion in the ecm connector. This was on a cummins though, not sure if the cats had the same issue.

I've had one that had the allison tcm go bad because of corrosion. It was located in a spot under the chassis and behind the axle, which imo, is a poor spot location for a control module.

Moral of the story, though, is what christopher said and that your issue is with the j1939 comms circuit, so you should check it for shorts/opens and then each connector for issues.

Like you said, the speedometer is the "master gauge" so if swapping it with a known good part didn't fix it, then I'd say the original is fine.

Good luck! These issues can be a bear to work on occasionally.

[cadillackid]

good to know about the corrosion at the fuse holders.. ive run into chaffed wiring harnesses on these before.. I fixed a couple A/C systems that were shorting down internittently.. seemed to me like the care involved in routing wiring on these was less than ideal at best...