Hi all

I have a 2001 4Runner with 165k on it. I've been chasing an electrical gremlin for the last year. At random intervals, the battery light will come on. The first time it did, I replaced the alternator and battery. After that it did not appear for 6 months, now it is back and will sometimes go out on its own, sometimes go out after shutting down and restarting.
I now have a 3 month old remanufactured Denso alternator. One year old battery that visually checks good with a green indicator in the status window. Terminals and shoes are clean and greased. New drive belts. No evidence of prior owner hacking into wiring.
There appears to be no drain on the battery, it'll start the next morning.
The light is now happening 2-3 times a day. The light flickers at idle, and is on solid at higher rpm.
I'm getting a multimeter today, to look for voltages and draws.
Any particular location I should start at?

Thanks.

 

start testing at the battery engine off. Then at battery, engine on. Then at the supply line at the fuse box. There is a plug by the under hood fuse box, yours should be black that the battery/alternater harness plugs into. Pull that apart and check for any corrosion.

 

Also check the belt tension.

i have seen connections that looked fine to the eye but were corroded enough not to conduct . Yet checking both sides of the plug with a meter gave a good reading.

Enough to get one real frustrated.

 

Frustrating, sure.
I bought a multimeter and with the threat of using it, the car has not tripped the light since...
Battery voltage is 12.6 and alternator charges at 14.1.
A thorough cleaning of all connections to follow.

 

Edited: on my '99 T4r the plug is gray. vital22re Thanks for the lead on this subject. It turns out the white wire midway between the alt and fuse box had a cut in the insulation which let the copper wires corrode and break. Once I found the break, it was easy to solder a splice in and get the truck running again. What helped was checking for continuity of the wires from both plugs. The white wire was dead but if I pushed on the wire harness it would make a connection. Also the white wire should have constant 12v even when the engine is off. Anyway, here is a picture of the plug in question.

I think this is the one you are talking about but mine is grey


Thanks