Thread: Battery light and temp light flashing

I have an 02 grand Prix gt. Recently the battery light and temperature light have been flashing. They tend to turn off at high rpm or idle. I tested the alternator and battery voltage with my multimeter, 14.1 and 12.8 respectively. The battery is 5 years old but it seems to hold voltage. I also confirmed the temp is in range via the Torque app and obd adapter voltage is 14.1 when running. I have a few questions

1. What if anything do these 2 lights have in common as far as wiring.

2. What triggers the battery light coming on? It doesn't seem like it is coming on due to voltage issues as verified by my DMM.

3. Could this indicate a failing alternator even though the voltage is acceptable?

4. What else could cause these lights to come on?

Thanks

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Is the car overheating at all? the only thing i can think of is something wrong with your pcm in the car, if both alt and battery testing good, and those two lights seem to be not connected at all.

A battery light normally indicates an alternator not producing enough volts to charge the battery. Have your alternator checked out at a parts store. Normally it's free.

Wouldnt hurt to clean all known grounds.

The car is not overheating as indicated by the temp gauge and through Torque. No other evidence of overheating.

Would the parts store do anything more than checking the alt. Voltage like I've already done? I.e. current supplied

Originally Posted by Fivefingerdeathpunch

Wouldnt hurt to clean all known grounds.

That's a good idea. I cleaned the battery terminals but didn't check the grounds.

One thing the temp and charging system have in common is the accessory belt. I thought maybe there was a problem with the tensioner or belt slipping. This would explain the coolant temp sensor getting bad readings if the water pump was turning too slowly as well as the alternator underproducing. The belt seems like it's under enough tension tho and I didn't observe any slipping visually.

Water pump was replaced in the spring along with intake and valve cover gaskets.

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Originally Posted by Mirraco

Is the car overheating at all? the only thing i can think of is something wrong with your pcm in the car, if both alt and battery testing good, and those two lights seem to be not connected at all.

You were pretty much correct. There were wires exposed going into the pcm. I taped them all and put a fiberglass shield made from a hockey stick on and zip tied it together. This solved the problem. I'm lucky that is all that happened...

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if you saw bare wires its best to cut that wire, solder and shrink tube it to seal it off. tape sucks, air will get to the bare wire and kill the wire. its called dry wire, wire looses its shine becomes dull like copper does when air hits it, then it no longer flows current right.

Originally Posted by ScottyDoggs

if you saw bare wires its best to cut that wire, solder and shrink tube it to seal it off. tape sucks, air will get to the bare wire and kill the wire. its called dry wire, wire looses its shine becomes dull like copper does when air hits it, then it no longer flows current right.

Thanks for the advice. I will do just that when I can find time

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dont let it go to long. dry wire will kill the wire thats insulated still, when i changed my maf pig tail i had to strip off 8 inches of wire till i got to clean shinny copper wire. i was 2 inches from opening up the main harness.