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Old 10-18-2008, 04:13 PM   #3 (permalink)
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Location: South Dakota
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WonderWagon - '94 Ford Escort LX
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Quote:
Originally Posted by chevysilverado View Post
With the engine running and a buddy holding down the power window button and flicking the lights I was able to determine that the alternator drops to about 10-11 volts while the accessories are calling for a large load. I had him give it gas and it shot back up to 13.5-14 volts.
The serpentine belt seems to be in good shape but squeeks a lot while the truck is warming up in the morning. If the belt was slipping then I don't understand how the accessories effect it.
Any thoughts? All input would be appreciated.
Not sure what to do other than replace the alternator at this point but don't want to spend the money if theres a possibility it's something else.
Not just a possibility it's something else.
It is most likely something else!
The more demand (demand = voltage drop) placed on the alternator, the harder it is to turn. So the belt slips more.

Procedure to fix it -
  1. Take the battery cables loose.
    Use a wire brush on the battery posts and the battery cable ends until everything is bright and shine.
    Reconnect the battery cables.
    (90% likely to cure the problem. Test it. Start up and check voltages with and with out ALL ACCESSORIES ON. If voltage drops below 13.0 you still have a problem.)
  2. Check that all starter cable, ground cable and alternator charging wire connections are clean, tight to wire and securely fastened.
    If you're a belt and suspenders kind of guy do this step even if step 1 fixed the problem.
  3. Replace the serpentine belt and check the belt tensioner while you're at it.
    How many miles/years on the current belt. Might be a good idea to replace it regardless of steps 1 and 2.
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