Overcharging

[Kalaehina]

My 96 started to overcharge and the GEN light came on. Installed a new alternator and the problem went away for a few miles, then when I was driving it last night and got on the throttle a bit the GEN light came back on and it began to overcharge once more. I noticed if I slowed down a bit and turned on the A/C it brought the volts back towards normal and the GEN light went out. This is the same way it was behaving before I replaced the alternator. I'm going to test the batteries today and the new alternator just to be sure. Maybe battery cables? My truck does have an oil leak that gets everywhere under the oil pan, could that mess with that speed sensor down there? Not exactly sure what it's called but I remember having to remove it when I did the KDP. Any help is appreciated! Thanks!

 

[GAmes]

Have you checked the battery temp sensor that is under the left side battery? The spec is in the factory service manual. When they fail the PCM voltage regulator is affected.

 

[Kalaehina]

Thanks, I'll check that out as well. I did notice that one of my positive cable connection on the driver side a little loose but I wonder if this could cause anything like overcharging?

 

[GAmes]

I doubt it, but since you need to tighten it anyway you can see for itself.

 

[Kalaehina]

Replaced the battery temp sensor, so far seems to have fixed the problem. Thanks for the help! Just wondering why it seems only one battery gets the sensor?

 

[GAmes]

Both batteries charge together, but it is the temperature of the air, not the batteries that influence charge rates. '96 and earlier temp sensors are mounted on the PCM.

 

[Kalaehina]

Got it! Thanks!