Greetings all.
I recently noticed a number of "faults" on my 1997 Convertible XK8 and came to the conclusion that the BPM might be the culprit. The faults were as follows:- windscreen washer pump not working but wipers OK, overhead courtesy lights not coming on with door open but each one worked with the push switch, glove box light not coming on with open glove box, footwell lights also not working and boot (trunk) lights not coming on. The BPM is responsible for all of these hence my conclusion that it was faulty. I ordered a replacement unit with the same part number LJA2500AG/XXX which had come off a similar X100 and installed it. The car would not crank. All the dash lights came on as per usual and the central console also lit up. Replacing it with the original unit (also an LJA2500AG /XXX) the car started. Just in case my replacement unit was faulty, I returned it and procured another unit. After installation the result was the same, no joy. I was under the impression that as long as the replacement unit was off a similar car that this would make it compatible. Has any forum member ever replaced a BPM or know if any special procedure is required?
Thanks in advance!


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Thanks in advance!

 

The XXX part of the VCATS number needs to match also, but that shouldn't stop the car starting AFAIK.

I think I would be diagnosing your individual faults further as things like the boot light and washer pump not working are common problems nothing to do with the BPM. For example have you tested for 12v/ground at the washer pump itself or tested the pump out of the car?

 

Hi dibbit, thanks for your quick response.
I checked the pump and its circuit when I was initially fault finding and it works if you apply 12v. As I looked into the other “faults” I began to suspect the BPM.
As far as the XXX on the unit having to match begs the question of where you the numbers and when buying a replacement how you would specify them as the breaker may no longer have the car.
As I mentioned previously, with my unit the car starts but with either replacement it does not crank.
Some info is missing…..

 

VCATS

 

Thanks motorcarman. I have found the tech bulletin (418-03) that deals with the control modules compatibility and the s/w version that is specified by the VCATS label.
I will contact my supplier to see if they are able to provide me with the s/w version from the donor car.
I'll let the forum know how I get on.

 

I suppose the obvious question I should have asked is did the washer etc work with the replacement BPM?

Unfortunately breakers don't seem to record the VCATS label itself so you don't know the XXX part of the module - the only thing you can do is get one out of a car that matches yours as closely as possible.

It does sound like the transponders or the immobilizer needs to be setup again with the replacement BPM - maybe someone else can confirm this? Otherwise it's a bit coincidence that two new modules don't work.

 

European MY97 cars have the security chip-in-key that is interrogated at start up. The BPM plays a part in this process (see attached).

Providing a replacement cures all your other issues, you may need to perform an IMMO SETUP to get the modules communicating as they should, even if the /XXX revision matches.

 

Hi michaelh,
My LHD car was sold in the US, so does that mean it may not be a key / security issue?
FYI the washer pump doesn't work with the replacement BPM, neither do the courtesy lights etc.
Do you have a description of the IMMO SETUP you can let me have?
Many thanks.

 

If your car is ex-US, then it's very unlikely it will have chip-in-key. This post from DevonDavid shows where to look for confirmation:
https://www.jaguarforums.com/forum/x...7/#post1682276

The security setup is therefore simpler, but the ECM still sends a data signal to the BPM to confirm start. I am not sure in this case whether programming is necessary or not.

Note also that any replacement BPM needs to have been sourced from a convertible, since one from a coupé won't 'know' about the convertible top.

So, which issues are resolved by swopping out the BPM?


P.S. Immo setup is a function in Jaguar's proprietary diagnostic kit (IDS)

 

I can't be sure about the X100 but I have swapped BPMs from X308 sedans with matching VCATS with no problems or configuration.

 

Unfortunately none of the “faults” seem to have disappeared with the replacement BPM, which doesn’t bode well. However I would be more confident if the motor turned over. I’m waiting to find out which s/w version I’ve been given and will take it from there.

 

If replacing your original BPM creates an additional fault (the no start), I suggest you revert back and revisit each item separately as suggested.

If the map lights work on the switches, then the BPM is providing the 'illumination enable' output B+ supply to them, the trunk lamps, glove box & vanity lamps in the sunvisors - are the latter also working?
Footwell lamps are on a separate output from the BPM.

F5 and F7 in the driver fascia fusebox, and F17 in the passenger fascia fusebox (all 15A) provide the three separate B+ inputs to the BPM. Check if any of them have popped.


Sounds like you may already have the 97 electrical guide?

 

Hi michaelh,
With the original BPM this allows the car to start. With either replacement units the car will not start. Sorry if I wasn’t clear.
I’ll come back to your other points later.
Thanks!

 

Unless I really have misunderstood, then swopping the original BPM didn't fix anything, and created an additional problem that the car would no longer crank.

Re-fit your original module and start from there.

 

You have understood correctly.
Back to the drawing board.

 

A small but vitally important detail, lol.

As Michael has said, put your new BPM in a box in the shed and forget about it.

I would now pick one of the faults you list and work your way through it. Maybe start with the boot light - a common fault is a break in the cable at the hinge.

Check the door open microswitch is working.

For the power wash I would be checking power and grounds with a test bulb and work your way back to the BPM.

All tedious, but easy to do and a lot easier than hoping that swapping the module will cure everything.

 

I guess I’ll have to bite the bullet and knuckle down with the fault finding.
Thank you all for your help & suggestions.
I’ll report back when I discover what has caused these problems.

 

To update those who may be interested, the culprit behind the faults was the 15a fuse F7 on the driver’s side that had blown; mentioned above as a possibility by michaelh. Replacing it made everything come good.
In a way, my initial diagnosis wasn’t wrong as the BPM wasn’t doing its job but through no fault of its own!
A lesson learnt that sometimes it can be down to the simple things. Thanks again to all.

 

Glad you got there

Quick q: have the sun visors ever been removed & refitted?

 

Not that I know of. Anything I can help with?