hawks05

Ok so the battery light has come on every once and a while, while im driving. It starting to come on more and more and staying on longer as well. I have read that this usually is a sign of the alternator going bad, but Oriellys hooked it up to their handheld and said the battery and the alt are good. Now i have read that this is usually the case when tested at stores like this that the alt shows to be good but will eventually die. just curious on what yalls thoughts on this are.

Need input ASAP!! so i can order a new one tomorrow if it is the alt.

Repzard

I had this same issue last year with my 99 GT.
Ended up being a weak Battery bought a sear diehard gold and all was good.

DRAGUL

I never trust auto parts stores to tell me parts are ok. I have brought batteries in which I knew had dead cells. They would test it, then come back and tell me that nothing is wrong with the battery.

cliffyk

The handheld quickie testers used by the FLAPS are only a little better than a go/no-go gauge and are not good at determining which component is bad in intermittent/failing system. You need to have a high current load test done on the battery, a good auto-electric place can do that or you can buy a tool at Harbor Freight to do it yourself.

The 500A carbon pile tester is the best, the 100A resistance coil unit is OK.

You could also rule out wiring problems by measuring the voltage between the generator output terminal and the battery's positive terminal (engine hot and idling), it should be close to 0.0V--and between the generator body and the negative battery terminal, that also should be close to 0.0V.


Here's a link to the Charging System diagnostic & test procedure from the shop manual.

Repzard

Cliffy to the rescue

04BlueGT

I hate to reboot an old thread, but I need help.

On 9 July, my battery light came on, stayed on a few minutes and then went off. It stayed off until 21 July. It was intermittent on/off for a bit, so my wife took the car to Sears installed a new Die Hard 2 years ago. The light was off when she got there and the only fault they found was the battery (which is hard to believe).

All was good until Monday, when the light came back intermittently. I checked the cables for tightness and serviceability and all seems in order. The belt is new and not slipping and the tensioner seems plenty strong.

Besides the alternator and/or the internal voltage regulator, what else may cause this and how do I "catch" the failure with the light on? I'm assuming the code reader is worthless in this case, but I have a multi-tester handy most of the time.

hawks05

For me it was the alternator. I had the old one tested and they claim it was working just fine, but it wasn't. I had checked everything and the only fix was a new alternator.

SXGT

you got motorcraft right?

hawks05

No, i went with a performance one.