2000 LeSabre, gremlins in the modules!

[crazylesabre]

Hi all,
I recently purchased a 2000 LeSabre Limited with 62k on it (really!).

I think Stripe from the Gremlins movie is living in the trunk.
First, when I got it, the headlights didn't work, as well as the power windows and door locks.
Headlights were easy, new headlight switch and 4 new bulbs and that was sorted.
When I drove it home, the the A/C, radio and gauges all worked.
Now, several days later, after new plugs, plug wires, hoses etc (no wiring was touched) when I start it, the gauges, dash lights and radio come on in the run position, but about 2 seconds after it starts they all quit, and the security light comes back on, but the engine still runs fine.
It was suggested that the key may be a little wonky, so I got a new PK3 key cut, but not programmed(I was planning to use the original key to program the new one).

If I use the new unprogrammed key, the car behaves the same as above, everything quits in the dash, except the car stays running!

Occasionally with the real key, if it has been idling for awhile, the security light goes out and everything comes back on and everything except windows and door locks work again.

I scanned the ODBII port with my Bluedriver and got 60 (!) codes, mentioning just about every module in the car. About half the codes suggested the fix was to replace the BCM, which seems to be Rear Integration Module. I have no issue doing that, I just wanted to see if some Buick gurus could chime in and tell me if I am even on the right track.
TIA,
Mike

[Blue Bowtie]

Welcome Aboard!

Depending upon what DTCs were retrieved, there is probably a pattern or something in common to many of them. Also, depending upon the diagnostic chart, replacement of an item is usually the last step in the sequence.

It also sounds like the PassKey III situation is not fully resolved yet, potentially skewing the diagnosis.

[crazylesabre]

Thanks Blue Bowtie.

I bought the original set of shop manuals for it, and just as you said there are exhaustive checklists for most any problem, most seeming to end up with replacing one module or another. The only issue is they expect you to have a GM scan tool with all of its bidirectional capabilities. That would be nice
Still, those manuals are a bargain for the information about every piece in the car.
I also agree with you that a lot of those codes are "cascading", where a problem in one module affects how the other one works etc.
I noticed a lot of common errors in the list of codes. Since the RIM was mentioned so often I went ahead and fired the parts cannon at it and bought a RIM and DIM module. I got them used, so even if they don't help, it wasn't a major investment.
They should be here this week, so I'll post my results when I get them installed.

Mike

[Blue Bowtie]

The chances of two modules being defective is small, so your method seems reasonable. A used part may resolve the issue, and even if not will not break the bank.

As for the scanner, even though it gets less and less use all the time, I'm glad I kept the older Snap-On MT2500 and bunch of profile modules I have since it is invaluable when these issues arise. It's surprising how many places traded in or dumped their pre-ODBII stuff instead of stashing it away.