Car model and year: 2003 XK8 convertible with 93000km
– Rain detector doesn’t work
– Steering column doesn’t retract sometimes
– Day/night auto light doesn’t work
– No MIL lamp or message
Those are not big things, but when I read out the BPM fault codes, there are many and I don’t feel confortable with them.
Body Processor module fault codes from my reading device (Foxwell NT624 – nice tool!)
U1041 Vehicle speed not obtained
U2012 Communication bus error
B1595 Ignition switch – Illegal input code
B1897 Horn switch – circuit failure
B2368 Column adjust switch – out of range
B2351 Column adjust switch
B2331 Column drive reach out of range low
B2334 Column drive tilt out of range high
B2335 Column drive tilt out of range low
B1446 Wiper park sense – circuit failure
B1875 Turn signal switch left and right switch active
B1450 Wash/wipe switch circuit failure
I would like to narrow down to the root cause of those failures, I am suspecting the following possibilities:
– Bad earth or B+ connection somewhere
– Bad connection in the BPM connector
– Partially faulty BPM module
– Partially faulty ICM module
Where would you begin the troubleshooting?
(The battery looks fine)
Good guess from friend:
Well, from your symptoms alone I would look at the rear view mirror and its connection to the BCM, since the rear view mirror has both the rain sensor and the day/night sensing function. It’s probably not the rain sensing module itself since the auto headlamps don’t touch that module and it is wire ORed into the stalk connections which might affect the function of those, too.
The steering column retract is probably a separate issue. Given the ignition switch illegal input code – and I don’t know what that code really means except from its name – maybe the little flap in the keyhole is a bit slow to return and that confuses the software. You could try lubricating it gently (not WD40).
As for all the BCM codes, it might be that you have the whole history of the car stored there, some of them are triggered by indirectly related faults, etc. Once you think you have them all recorded You could try resetting them and seeing if some come back, if any.
After spending quite a bit of time (and whisky) with the schematics and the repair manual I made some pinpoint test and resolved the issues. (Also thanks to my friend with his good guess)
Rain sensor: disconnected connector in the rear view mirror assembly
Light sensor for automatic lamp: dislocated sensor in the same unit
Radio and cigar lighter power after ignition key removed: sticky relay in the passenger side fuse box
Before assuming that this was an easy task, I also made many unnecessary thing:
– Resistance tested the SCP network, which led to the conclusion that my car is an XJ not an XK (SERVICE TRAINING COURSE MXAD MULTIPLEX ADVANCED DIAGNOSTICS 02/15/2002 section 3.6)
– Removed and cleaned the ignition switch, because resistance measurements showed fluctuating, uncertain values. (I don’t recommend to anybody doing the same, because it is not a serviceable part, easy to loose small parts and cracking plastics)
Many thanks for your advices, I enjoyed (still enjoying) to discover the complexity of this car.
(Until I can resolve issues…)