Battery light on

[callofktulu35]

Here's the story..... My buddy has a 96 RS and about 3 weeks ago he got a new battery. Last weekend we brought the car over to my brother in laws house to do a tune up and oil change and he told me that on the way over the battery light came on. So after trying to narrow down why the light came on he then mentioned to me that when he installed the battery he "accidently" put the battery on backwards. +to- and -to+. When we brought the car to my bothers house it was the first time he had driven the car since the battery replacement. Could he have fried his alternator? His radio and blower motor are also in-op as well. Or should we check specific fuses first before removing the alternator and taking it to get tested. Also, he said the light came on about 5 minutes after driving it to my brothers house. So ive eliminated the ECU being shot because it starts and drives.

Thanks,
Robb

 

[CrawlHer]

Sounds to me like he shorted the battery and then gave up the ghost after he drove it for a few and the battery warmed up a bit. Puked the battery and have it tested at Autozone.

 

[97tal]

check the voltage on the battery with engine off then engine on. If voltage doesnt rise when motor is running then the alternator is bad.

 

[Iyaoyas]

another way to check your alternator is have the car running and unhook your negitive battery cable. If the car stays running then your alt is good, but if it dies then your alt is bad. That is a way to check if you dont have a volt meter.

 

[jayson427]

if he did that then he blew the fuses. a/c and radio should be under the hood fuse box. i would check them all. for the battery light i would check your voltage mine has been on for a long time never figured it out.

 

[KewlWinter]

If your battery light is still on after your battery and alternator test good, then swap out the ECU. The regulator and voltage monitoring is in the ECU for the 420A cars.

 

[callofktulu35]

another way to check your alternator is have the car running and unhook your negitive battery cable. If the car stays running then your alt is good, but if it dies then your alt is bad. That is a way to check if you dont have a volt meter.

I'll have to try that, We aren't going to start playing with it till Saturday.

if he did that then he blew the fuses. a/c and radio should be under the hood fuse box. i would check them all. for the battery light i would check your voltage mine has been on for a long time never figured it out.

We checked the fuses and they all seem to be intact. Except the relays, Haven't checked those yet. Can't just visually inspect them. We have to test those at the source. Yet another project for Saturday

 

[callofktulu35]

Now i'm confused. Took the alternator out of my buddys car today and it tested good at Advance Auto. The battery is new. The battery light is still on. Please tell me this is just something stupid i am over looking. I was 75% sure that the light would be on because of a bad alt. But NOOO the alt tested good. Is there anything i should check tomorrow? I really feel like this is going to drive me insane. ha ha

 

[alumascoupe]

Battery being new doesn't mean its good, esp. after hooking it up backwards. I've heard AZ and other rebuilt Alts can trip the ECU voltage regulator, even while testing good, no 1st hand experience, just hearsay. Also removing your batt. cable while the alt. is charging can cause bad voltage spikes and ruin your voltage regulator, whether its in the alternator, or the ecu like a 2G.