Update on BCM - Interior Lights Blinking, I can't believe this!!!!!

Several months a go I had interior lights that flashed randomly off and on. I had diagnostics done and told it was my BCM. The guy took out my key-less entry, broke my strip on the door that has the windows and seat adjustments. At least I found out what it was.

I got a new Body Control Module, only to find it wasn't it. The lights still flash. I took it to another mechanic. I asked if I unplugged the door switches one at a time, would that tell me witch door it was? He asked what else controls the interior lights? I thought of another part that does it, the light switch on the dash.

I was sitting in the car with the lights flashing, I pulled the light switch out. The lights quit blinking. I opened the doors, they came on. Closed them, they went off. I put the light switch back in and they started blinking. OK, seems pretty clear the problem was the light switch in the dash.
After getting a new light switch, the interior lights quit blinking. I happily drove the car for two days fixed. Well, what do you know? Tonight, it started blinking again. I can't believe this, I'm over $400 into this and my lights are still blinking!!!

I asked the dealer for an estimate. They said they would have to start at one end off the car and go through the whole thing. I asked if it could be thousands and was told, "yes, it could be."
What do I do? Any suggestions on what it could be?

If I unplug the door shut sensor and they quit blinking, how would that tell me it's the problem since removing the light switch worked but wan't the problem? Chris.

Try checking your door latches. The latches have the interior light switch built into them, and after time they can wear out (as mine did) and cause light problems! My lights didn't flash, but they would either stay on all the time or would stay on and shut off a long time after the doors were all closed. Here's a good quick test you can try: Open all of the doors and use your finger to manually latch the door in the shut position. This should shut the lights off. Now turn them on with the dashboard switch. Last part of the test is wiggle the closed door latches (starting with driver door). The lights should stay on, but if they flash as you said they do when you're driving, then you will know right where the real problem is! If you try this, don't forget to unlatch the doors before closing them.

Thank you for replying.
When I said Light Switch on the dash, I meant the dimmer/Interior lights on, switch.

I don't think it can be the door switch. With the dimmer switch out, the doors shut, lights go off like there supposed to. Open doors, they come on, close them, they go off. So the door switches seem to work fine in all areas like supposed to. When I plug in the dimmer switch, that's the only time they start going off and on.

I wold just drive without the dimmer switch plugged in, but when I turn on the head lights, the dash lights go so dim I can't see them. Chris.

I am just repairing my cluster in my '87 - with a dimmer switch problem. The problem wasn't the switch itself, as it seems like it probably is not for you.

Yours sounds like a loose wire sort of problem, maybe a loose ground. Does it blink when you are still? Does wiggling the connector do anything?

Keep in mind I don't have blinking, my problem is totally different, but without knowing your year I can't tell you if the quality of your behind-the-dash wiring would be as bad as mine is (assuming yours is newer too, since you mention "dealer")

...

Mine is a 1997. It does blink when I'm sitting still. I wiggled the wires and it doesn't change anything.
I found the lights are supposed to be hot all the time. When I turn on the lights, it grounds the circuit. If it was a ground problem, it would blink off when the lights are on. My problem is when there off, they blink on.
If I knew what I was doing, I could figure this out, I'm right on the verge of it but don't know enough about electrical to get the last bit. Chris.

Too bad I don't live near you. I was on your side of the country all my life until a year ago...

Anyway, since it blinks, I should ask - does it blink randomly or is it uniform? I don't know how the blinker system works in that car, but if it is shorted to that then that is where your blinking could be from. Do you hear the flasher unit clicking (assuming yours has a normal flasher unit? I am used to my old car) I do know that though my cluster had really messed up grounds, about 2v was going through my cluster lighting system (enough for some LED lights which I temporarily mounted) and it'd blink on/off when I used my turn signals. Again, this ultimately was because of my bad grounding situation. Yours may be shorting to the blinker unit, which would cause it to blink when the lights are on, since that'd complete the circuit.

If it is random blinking... I have no idea :/

According to the Haynes manual, you can pull the Interior lamps relay at position F, probably located on the passenger side fusebox (check owners manual). This will (according to schematics) only allow the interior lights to be activated by the instrument dimmer/dome light switch.

If this solves your problem, I can suggest which wires to test if you know where your remote accessory control module is.

Good luck

[QUOTE=kram5527]you can pull the Interior lamps relay at position F, probably located on the passenger side fuse box (check owners manual)(/QUOTE]

I'm using a copy form a Mitchell Repair for a specific 1997 Lesabre. I see it's different from the one I have in my Haynes 1988 and Later models diagram. The "Interior Lamps Relay Position F" in the Haynes manual isn't on the page I have that's specifically for my car and year. Any other suggestion?

I almost had it. I went to the college and asked the teacher. He looked at the diagrams he has and was asking me interesting questions. One was after he thought it most likely was the switch, he asked me when the lights blink, does the light in the ashtray blink. No. OK, it can't be the switch since it is hooked in with the switch. The (School shop) lights went out, everybody was leaving told him I would come in the next day. When I did, I found out he is very sick in the hospital. Blood Pressure went sky high and some other health problems.

It seemed like he was so good he could trace it down pretty much without ever seeing the car. He can tell just by looking at the wiring diagram. Keep suggesting what I can do to figure this out. I have my Dash torn apart and would like to get this fixed. Thank you for replying,
Chris.

I haven't had reason to pull my interior light dimmer yet and as you said, the Haynes manual is not specific. If you have a reasonably good multimeter and a few minutes you can try the following:

1. pull the dimmer/interior light switch out
2. probe all of the connections using the resistance function on your meter
3. for every pair of connectors you test, move the dimmer switch and see if the resistance changes
4. once you have found the pair that changes the resistance of the circuit, check if the resistance drops to ~0 ohms
5. if the resistance for this pair does reach 0 ohms, you should be able to jumper these two connections (at the wiring harness) allowing full power to your instrument lights. You may want to use a fused jumper with no more than a 5 amp fuse.