1993 LeSabre - Electrical Problem

My 1993 LeSabre seems to have an electrical problem. The SERVICE ENGINE SOON light switches on, after which the headlamps and interior lights dim noticeably. There doesn’t seem to be any discernable difference in the way it drives, but the lighting problem is disconcerting enough.

Does anyone have any suggestions as to what could be causing this problem?

Take off the battery terminals, and clean them properly. Make sure there is no corrosion left on it! Start their first!

Take off the battery terminals, and clean them properly. Make sure there is no corrosion left on it! Start their first!

As a matter of fact, I just had that done over at Jiffy Lube this past weekend when I had the oil changed. The problem with the SERVICE ENIGNE SOON light made me think that it was a battery problem, so I had JL clean the terminals. They also coated the terminals with some kind of purple stuff.

Could it be the alternator? I had it replaced a year (and an old transmission) ago.

Ok then its not corrosion! If its setting the check engine light, you may want to pull that code when it sets next time!

I dont understand why the light will dimm, unless something is beeing shorted out somewhere!
The Service Engine Soon light monitors the vehicles ECM and sensors. Maybe the wire for the ECM is not getting sufficent power?

You can get your alternator checked out for free at Auto Zone. Do it!

Ok then its not corrosion! If its setting the check engine light, you may want to pull that code when it sets next time!

I dont understand why the light will dimm, unless something is beeing shorted out somewhere!
The Service Engine Soon light monitors the vehicles ECM and sensors. Maybe the wire for the ECM is not getting sufficent power?

You can get your alternator checked out for free at Auto Zone. Do it!

OK, I'll get that checked on my way home today.

GM usually puts in an idiot light to light up when your alternator is not working or putting out enough power. i would think the vehicles alternator is working correctly if this isnt illuminated. the best method is to pull the codes and from that aspect we can determine if or why it is causing the lights to dim. i am thinking its causing the engine to output fewer power and thus diming the lamps.

Did you check to see if JL didn't strip the threads on your battery terminals?

Did you check to see if JL didn't strip the threads on your battery terminals?

Yes. The terminals are fine. This problem had occurred prior to my visit to JL.

I had the alternator and battery tested at Auto Zone. Both checked out fine, and the folks there recommended that I replace the ground cable. I'll replace all of the terminal cables leading to the battery this weekend and see if that makes a difference. I'll also take the car to the dealer and verify the code from the computer.

I had the alternator and battery tested at Auto Zone. Both checked out fine, and the folks there recommended that I replace the ground cable. I'll replace all of the terminal cables leading to the battery this weekend and see if that makes a difference. I'll also take the car to the dealer and verify the code from the computer.


I too think that it's a ground issue. Check all of the body grounds under the hood. They can mess things up. Do a search on this I've posted a few times about it.

Regards

Dan