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Bizarre Electrical Problem in 1998 Oldsmobile Silhouette

I have a 1998 Olds Silhouette with a strange electronic problem. This last summer, my kids told me that both dash turn signal lights were illuminating every time I hit the brakes. Then when we took the van on vacation this summer, I noticed that the cruise control would turn off sometimes when I used the left turn signal. Then near the end of the trip when this happened the TCS and ABS system went off. The system reset when I stopped the van, turned it off and restarted, but then the auto sliding door which had not been working for a couple years suddenly started working. I’ve noticed since then that the load leveling system has quit working. Now the ABS and TCS randomly go on and off. Also now the rear driver lights are now much dimmer than the rear passenger side. When using the left turn signal and braking the the blinking rate gets very high and other rear lights blink too. Is this an electrical or computer problem. I’m stumped

How about telling us what codes have been read.

I don’t think we’ll ever see those.

Judging from the post neglect plays a big part here.

You neglect electrical faults and they snowball.

About both turn signal lights flashing at the same time and the lights in the rear being dim, I would bet that you have bad grounds at the tail lights.

Your car probably has a ABS module a TCS module,I know it has a module for the sliding door and a cruise module, I would have to look at the schematic (which I don’t have) but they probably either connect to the BCM (Body Control Module) or are on a data bus together.

After a schematic overview I would see if I could communicate with these modules with the dedicated GM scanner the TECH2.

If I could talk to all modules I would look at the wiring for some kind of damage.

You have looked at you battery connections (at the battery) GM batterys liked to leak acid at the postive terminal,this acid would damage the postive cable and strange stuff would happen with the electrical system. This could be a rodent damage situation.

That is a pretty good laundry list you have there.

The turn signal/brake problem may be with the flasher unit. Both of the circuts run through it. There may also be a problem with the left rear turn signal filament. It may be crossing the running light filament. Hopefully clearing this trouble will fix some of the other things that are happening. The load leveling may be a seperate issue.