Replaced battery in January. A week later, the battery light would come on after driv9ing about a half mile, go out and stay out. Began to happen more than once. Research led me to believe the alternator was suspect, so I replaced it - didn’t know if it was the original or not. Car has 82K.
Light still comes on, now more than often. Had the charging system checked; all came up OK - no codes stored/tripped. Mechanic had the car for three days, of course, they could not duplicate the issue.
Now the light comes on when first started, goes off after about a half mile of driving. Comes on again sometimes.
I do notice that with the auto on lights, when I step on the brakes, the headlights dim, so I pul the car in neutral at stop lights, or in Park, if it is a long light. Thinking maybe it’s related to the auto light wiring? I park in a garage while at work, so the lights come on when I leave, and the battery light pops on again.
I had this happen for a bit after a new alternator. I had the same thing where the alt seemed to be having no trouble putting out power. The signal wire for the dash light was loose. I cleaned it up & plugged it back in & that was that.
I don’t know that this would be it - but I’ll assume a wiring problem. Its probably the same one that killed the battery and had you replacing the alternator. (Did you have the last one tested or just replaced it on a guess?) How are the main power cables and grounds?
The old battery was going - it was about 5 years old. Had about 102 CCA, so I knew it needed replacement. Alt was putting out fine when the battery was replaced, but you know how those things can just go. I did not know how old it was.
Is it possible then tech who installed the battery caused this? It didn’t happen before the battery went bad.
I’m technically challenged, so I woldn;t know what to look for as far as wires/cables. The mechanic said everyting looked fine.
I doubt the tech caused this problem. It sounds like a bad wire connection to the alternator may be the trouble. Most alternators have two wires going to the back side of them. One of them ties to the battery to monitor the battery voltage and the other wire supplies power to the exciter inside the alternator through the battery warning lamp that is tied to it in series. When the alternator isn’t running the connection for the warning lamp on the alternator is at ground potential so the warning lamp turns ON. When the alternator is running normally voltage gets backfed on the lead from the exciter and the light turns off since not enough current can flow to keep the light turned on. If something happens to the alternator then the charging voltage drops and that allows more current to flow through the lamp and it turns on again.
Check for a loose connection at the back side of the alternator and also the battery connection.
Wiring looks OK to me. Took it out this afternoon…light came on on start up, went off after 30 seconds. Came on for two seconds, out the rest of the trip to fill up. On the way home, came on for a few seconds and went off again.
This thing is possessed! And people wonder why I was always a Mopar guy!
I give up; will drive until it catches fire!
I DO remember when the battery was replaced, the tech forgot to put in the heat shield until after he was done, then he put in in place. Coud this be some sort of “extra grounding” or cause an intermittent short?
From the negative post of the battery, there should be a heavy cable going to the engine block (the block ground) and a smaller wire connected to the body structure of the car. (the body ground) . Make sure that body ground is in place…
You can’t just look at wires and say things are ok and be sure they really are. Proper testing will prove if things are really ok. I suspect the replacement alternator may be causing the trouble but once again, proper testing needs to be done to prove it.
Boy, do I feel like an idiot! Took a good look at the dash lights this morning…what I THOUGHT was the battery light was actually the low coolant warning! The car never ran hot - stayed under the half mark. Put in a coupole of pints of 50/50 mix today and it solved the problem. I usually check the level every two weeks, but I was out on medical leave for three weeks and didn’t drive fot that time.
The light is a square with a squiggle at the bottom…THOUGHT it was telling me :Low Battery".
I’m gonna go stand in the corner for a while and write CHECK YOUR COOLANT EVERY WEEK about 200 times.
Thanks all for the help. Seems I could have saved me a few bucks replacing an alternator that was probably still good.
Well lets say your timeout is over. You’re not the first one to do something like that. I’ve had my special moments also, like most other folks. At least you know your vehicle better now. Thanks for the update.