When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
So I've been trying to get to the bottom of the U0001 "High speed CAN communication bus" error for a while now. The car mostly runs fine, but it often jerks heavily when I put it from P to D, kind of like it did before I fixed the turbo actuator fault (Mr Muscle)..
When I clear the errors (Both the TCM and ABS modules give U0001 error) they usually come back after 30-60s. I'm not getting any check engine light anymore, but I was getting one last week but I think it was due to a dying battery that I've since replaced.
I used the iCarsoft LRII to look at TCM values, and I just picked out some because there's something like 168 values there. (some photos below)
Anyway, some of the readings from the LR II seem to contradict each other, which is kind of strange. For example, in the first image below it says:
Module Supply Voltage = 0, but further down it says:
Control Module Voltage = 14v.
Another says:
Vehicle speed ABS Failure = YES,
And further down again it says:
Vehicle speed ABS Normal= YES
And there's some other contradictions too, like in the RPM.
It's like the device is getting the values from different places, or something, but I'm not sure exactly what values come from where.
The -40 degree centigrade oil temp is a strange one. I'll have to look into the oil temp sensor. Note: -40C is also -40F, where the two scales meet, strange coincidence?
And the "accelerator pedal position" stays at zero when I press the pedal, but I definitely saw it working elsewhere, but the TCM doesn't seem to be picking this value up.
It's like some values are just not being received but other values seem to be read just fine all the time.
I also took off the TCM and had a look inside and everything looks fine. But the electrical connection on the gearbox (where the TCM connects) was kind of strange. It had a crapload of "something" inside it. It was like little soft chunks of soot or foam, but it wasn't sticky. I'm not sure it it was some substance in the connector that broke down, or something that got in there over time.
I cleaned it out, but it made no difference with the communications fault. There does also seem to be 2 pins missing on this connector but I can't find any details on this connector anywhere so I have no idea if there supposed to even exist or not.
Powers, grounds, and CAN wires all seem fine, and with only the ABS and TCM being affected by the error I can only assume it's an intermittent wiring fault between the two.
Unless anybody has some other ideas?
Could a faulty oil temp sensor be causing problems? I'd assume if it was faulty then it would show up as a fault, or "out of range" or something..