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Battery CEL, alternator or belt?

952 views 2 replies 3 participants last post by  dikkstarr 
#1 ·
So today at idle, the battery light is off. When accelerating, as soon as the RPMs go above 1800, the battery light comes on and stays on until the RPMs drop under 1800.

Using a multi-meter, the batteries read 12.75 at idle. Increase the RPMs to 1800-2200, and the battery voltage drops to 11.9-12.1 (at this point the battery CEL is triggered).

As the alternator is charging at 12.9, and the batteries appear to be full charged (12.7 at rest) I'm looking at possible other causes of the battery CEL to come on.

Alternator diodes?
Belt slipping?

Any suggestions from the TDS experts?
 
#2 ·
Most Likely its the alternator it should charge at 14+ volts if the batteries are weak the alternator should turn all the way on.
 
#3 ·
Last week my battery light started to flicker then stayed on.

When I wiggled the plug that plugs in to the grey part, it would charge and the light went out, but only if I put pressure on it a certain way.

When I split the alt, I found that the 3 torx screws that hold the assembly with the 2 brushes in it, were less than hand tight. I saw there was a metal to metal contact under each screw. I dont think these were making contact anymore.

You can split your alt and check these screws.
 
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