1988 Cadillac DeVille lights flickr while driving when the car is cold with new alternator

Question edited for clarity and remove non-existent word 'dint'.
Question moved to model category.

Intermittent faults are the hardest to diagnose. The only way is to find an auto electrician and his pro grade scan tool computer can record what is happening and what causes it? The first thing I would do is check all the grounds.

https://www.google.com/search?q=auto+electrician+near+me

https://www.google.com/search?q=1989+cadillac+deville+sedan.+alternator+not+charging+consistently

Low voltage does really strange things to the control modules, so replace the alternator, clear codes, charge the battery and drive on.

Could one WHAT be overcharging the other WHAT???

To understand the problem you must first understand that the car runs off of the BATTERY. The job of the alternator is to replace the power that the car uses back to the battery. The car DOES NOT operate off of the alternator (many people do not get this). The charge light comes on when the charging voltage from the alternator is lower than the voltage that is available at the battery posts (that is why the charge light is ALWAYS on when the ignition switch is on but the engine is not running.

If the CHARGING SYSTEM had been PROPERLY tested, you would have seen this in the tests. If you removed your alternator to have it tested, this does not test the charging system in the car.

This can be caused by a failure or high resistance in ANY PART of the charging system. This includes not only the battery and the alternator, but also all of the connecting cables, wires and the ignition switch.

If the battery and alternator are both good, then the problem is most likely a loose or badly corroded battery cable. However, high resistance in the ignition switch circuit to the alternator can also cause this type of problem. The charging system in your car needs to be PROPERLY tested to pinpoint the location of the fault.

Sounds like a faulty voltage regulator to me.Start the car and take a multimeter and check voltage coming out of the alternator it should be 14-14.6 volts if its not within these specs take alternator back and get a new one.

How old is the battery? I learned at Sears while working there in the battery department that the average life of car batteries is about 3 years. So, after that, batteries lose a significant amount of their performance CCA or cold cranking amps, and may have to be replaced on a pro rated basis after that period of time, on average.


I put a diehard platinum battery into my 1997 Cadillac Deville Limousine for about $189.99 plus tax and it has a 4 year replacement warranty due to bettery construction.

However, if you get Walmart's best Maxx battery, they have a 3 year replacement policy and they charge about $79.99. I put that into my 1990 Cadillac Deville.

Good luck on resolving the battery drain problem with a good alternator.

Sounds like the battery is weak or the alternator isn't providing enough amps to keep the engine running and power the lights at the same time.

Yep, check or change your alternator.

did you unhook the battery prior to installing the alternator

A 12V battery drain, doesn't necessarily mean a bulb is on. There could be 17,842 other reasons such as a sticking seat switch, blower motor staying on, I could go on. Need to have it tested for that,and identify the circuit with the drain on it. Then beginto search and see what is the cause. Hope this helps

Check things like glove box ,boot or centre console lights. Also while recharging battery with engine cold feel alternator for any heat. Does alternator charge?