My 2002 dodge caravan. 3.3l flex motor. 118k Battery light came on a few days ago. Concerned it was my alternator went and got the alternator tested and battery. Alt was charging at 14.7 volt and battery tested great also. Battery is fairly new.

Well we determined it was rusty and corroded terminals. i bought some felt washers cleaner and a terminal wire brush and cleaned them spotless. no more light. also never got a check engine code

Today i started my van and immediately light was on. no dimming lights loss of power ect... Drove it to orielly to have it tested. drove great no issues but the light. Alternator tested fine as did the battery but he said starter failed. started perfect no issues. i read a forum about the battery temp sensor controlled by the pcm. So i ordered the ambient temp sensor and continued driving/shopping till it came in a few hours later. Still no issues but the light. runs flawless.

Well the ambient sensor in the front facia was broken off the plastic just laying in the bumper. replaced it, cleaned terminals, grounds, removed all power wires and cleaned, starter, alt, ect.. removed alt and starter plugs and cleaned and secured. That damn light still comes on. I idled it for an hour with lights on an heat full blast. no dimming lights, check engine ect.. no change in performance. I also held the trip down to run self check and still no change.

Any ideas? Everything seems to be testing fine. good battery & alt. what could it be

 

Did you check the battery sensor under the battery tray?

 

Thats the sensor i was going to replace. but the dodge dealership said on my model it was the ambient air sensor in the bumper that controlls it. I removed the battery tray and there is nothing under it at all.

 

If your terminals were rusty and corroded, there's a good chance that one or more of the wires connected to them are going South as well. That stuff can work it's way down the wire, but you won't be able to see it of course because they're covered. You could do a quick test and add another temp ground with a jumper cable from the negative terminal to a good ground like a motor mount. If doing that shuts off the light, you can either replace the wire(s) or perhaps just add a second permanent ground wire. But it could also be a bad hot wire (under the IPM is a common problem), which would take more work to fix.