Please help me with the following issue on my 2003 XK8 convertible with 93000km

Symptoms:

- 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 (checked, fuse are ok, earth is ok)
- Bad connection in the BPM connector (checked, cleaned, looks fine)
- Partially faulty BPM module?
- Partially faulty ICM module?

Where would you begin the troubleshooting?

(The battery looks fine also, 12.6V)

Many thanks in advance for your kind advices.

 

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.

 

YES - many of these could be historic out-of-range errors which are no longer relevant.

But the "No MIL lamp or message" is worrying. The MIL should illuminate as part of the lamp check sequence on startup. If it doesn't illuminate during this check procedure then it may have been deliberately disabled to hide faults.

Graham

 

Naturally my MIL lamp and messages are working well, sorry for the confusion, I just tried to express that those faults are not trigerring a MIL lamp or any message. (As it is their normal behaviour according to Jag Diag handbook)
I also erased, confirmed that they are erased but those fault codes keep coming back in a few minutes. Exactly the same messages.
What is also strange, that a the BPM lose communication with my OBD reader sometime and start to communicate again after ignition on/off.
All the other modules doesn't have this behaviour, so I think that my reader is fine.
I also looked inside the BPM for "visual inspection" and no obvious sign of any problem.
Maybe I will try to replace it, but as I read, it is not a simple task...

 

They look like codes that would not be expected to put the MIL on, and probably the codes info in the workshop manual says that too - had a look? Free download.

 

Thank you, I have checked before and those codes doesn’t have to trigger MIL or write a message.
I think that the patient’s condition is getting worse, because now it started to leave radio an cigar lighter power on after removing the key, which naturally leads to battery drain.
I fitted a new battery, played with the starting key, but no help. Maybe I have the well known “bad BPM battery Drain” BBBD phenomena.
I am just missing the randomly starting horn and lights...

 

Still pointing to that ignition lock flap needing looking at.

 

Problems solved!

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 Mr. Pbuck, 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...)