Here we go again
1st I'll say what the original problem was, what I did and what is going on now.

Initially here is what was not working sometimes when I started my car. Whenever I had problems my car would not shift out of park, my turn signals would not work, no wipers, the bulb out indicator illuminates (which is the signal to me that the problem is happening) and no headlights.

I was told on this forum that it might be my brake switch. I took it off, cleaned it well and when I put it back on, the car was fine for a few weeks. After that it would mess up more often as time went on with the same problems noted above. I cleaned it again and the car messed up again after a week this time and again as time passed it would mess up more often. I pulled out the brake switch and checked the switch out. There is one NO switch and one switch which NC and both were working fine when I checked for continuity.
I was then told it was probably the BCM module which I replaced with a used one. The problem was fixed...until six weeks later when this same problem appeared and progressively got worse. I also checked for any pinched wires by the steering column and found none.

The car is almost undriveable at this point as the problems happens every time I start the car. After driving awhile the problem slowly goes away until it is fine. Of course it comes back when the car is cold again. This makes me think that the BCM is at fault and maybe has some cold solders. I plan on looking at that next.
Any ideas would be helpful. Is there a place I can send the module to be checked out? Are there any wires to the BCM that I should be checking for gnds and 12v to? Please enlighten me.

One last thing. I also own a 95 XJS and was wondering if that car has the same module. Now that it is laid up for the winter I can borrow the BCM from it.

Thank you so much,
Jomo

 

Jomo,
I havent experienced any of the problems you describe, but as I read your post, I did wonder about moisture ingress as a possible culprit. The fact things seem to right themselves once you have been running for a while struck me as a clue, Dry solder a possibility too, as you surmise, but seems less likely to resolve itself every time.
Just a thought

 

County, With respect to moisture are you thinking in the BCM itself?. I currently have the BCM out of the car and opened it up. The solder all look good which is not what I was hoping for and the board is dry. Exactly where do you think the moisture might be?
Thank you for your time,
Steven

 

I did a test today. I started my car and the problem was there. I immediately shut the car and swapped out the BCM with another one. I started the car and I had the usual problem with the 2nd BCM. I let the car run for a bit until the problem went away. I then shut off the car and put back the 1st BCM and when I started the car there was no problem.
So another words, when the car was cold the problem existed with both BCMs and when the car was warmer the problem was not happening with both BCMs. I want to conclude that the BCMs are both good.

Should I be looking at the brake switch at this point? Any other ideas?

 

Quote
"I want to conclude that the BCMs are both good."

You could also conclude that both BCMs are bad (or that the input/output wires or signals are bad).


You may have a problem with an earth point or power connection. I would suggest checking them all out for dirt/corrosion and tightness. You can find the information for the various points in the Electrical manuals that can be downloaded from the stickies.

You will need to drop a level of detail to resolve this I think. In these situations it is often helpful to pick a single component that is not working e.g. wipers and trace the circuits for that component from basics using the wiring manual to establish which input or output is missing and from where.

 

Consider the throw of the switch my be on a hair line between making and not making as it is installed in the device . There is a upgraded design of this brake switch if I recall

You are lucky you have the bulb out light on your instrument cluster as a test meter , weird

Is it only a one pole switch as you had it out ? If that is so then :

S/C engine the signal to the BCM is a serial bus signal . Look at the TCM long connector

N/A engine Look at the ABS connector as the wire goes through the LS3 or RS3 connector . RS3 connector is located down in the corner FWD of the ECU , and the LS3 is in the same place on the left side of the car .

https://www.autozone.com/electrical-...70662_0_0_5520

Editing : looking at the difference between normally asperated and S/C engines

 

I tried the car with a known good BPM and the same problem appeared.

I rebuilt the brake switch by replacing both SPDT micro switches.
Things are MUCH better now, but the problem still appears sometimes, but again much less frequently.

I also checked as many ground wires I could find but this did not help (I did this before rebuilding the brake switch).

Not sure if I mentioned this before but when the problem appears if I move high beam stalk the high beams illuminates and *sometimes* the problem goes away.

I keep thinking how this problem appeared after I changed a light bulb. It has to be related to the problem. Tomorrow I will once again go through the wiring for my low beam lights to see if I can find any problems somewhere.

Thanks,
Jomo