’97 Corolla DX lighting problems

I'm not sure what the Toyota people mean by "Main Control Module" as there are not modules in the car referred to by that nomenclature. If they are talking about the engine electronic control module, I doubt if that is the problem because there is no connection with headlights.

The odd combination of problems points to either a bad ground, shorted wire, or bad combination switch in the steering column.

If you are going tot look for a bad ground or shorted wire, start by looking at any aftermarket accessories like keyless entry systems, remote starters, fog lights, audio systems, and Ipod adapters because poor installation of those accessories is a common cause of odd problems. Check to make sure the ground wires for the rear lights are making good connection with body ground. Any body repairs in the area may prevent a good ground.

Also check the wires to the center high mounted stop lamp (CHMSL) on the spoiler and make sure they are not cut, chafed, or crimped, especially where it follows the hinge and connects to the wiring harness.

You will need an electrical wiring diagram and a volt/ohm meter to properly diagnose the combination (headlight, turn signal, and windshield wiper) switch in the steering column.

Hmmm....I'd be looking at the brake light switch to begin with, and (Good Luck!) a ground problem.

I think they may be referring to the 'relay integration module', what I consider to be a horrible abomination, since it contains the buzzer, a number of relays, the windshield wiper INT timer, etc. So, if one function goes out, instead of replacing a $7 item, you get to shell out $135 for a new module!

Not one of my favorite Toyota 'innovations'...

honda's done that too, called a "multiplex" box or something. the good thing is theyre extremely reliable, and mean less subassemblies to buzz, rattle, and break.

True...but when they do break, it's bad news.

Thanks for the reply, after several hours of searching, we found that the rear stop/tail lamp had one filament that had fallen over to the other and welded itself in place causing the problem. Once the bulb was replaced the problem was solved. It was difficult to detect this short because the stop lamp continued to be lit and the tail lamp was the one out. The stop lamp being the brighter bulb made it most difficult to see. The fact that the emergency was not affected by the short was the only clue to it being rear lamps, cause in the rear the emergency lights operate separate from the stop/tail. What a relief, this had most of the Toyota experts stumped.

Assuming this all happened at the same time, it smells suspiciously like a grounding issue. Check the cable from the battery to ground and make sure BOTH ends are well connected. Second, take another look at the light switch. It might have failed.

I had a similar problem with my wife's 97, but only on one side.

Ended up being bad solder in the sockets. I took the easy way out and replaced that cable assembly.

It may be the same idiot worked on both your cable assemblies...