Load Testing Alternator On Vehicle
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Load Testing Alternator On Vehicle
I made a brief video on the procedure I have used for many years here at the dealer that has not failed me yet in identifying a weak but functioning alternator causing many headaches like no starts after changing the battery and only checking the voltage output of the Alt. I hope this helps as there really isn't a need to take the alt off to get it tested. No fancy tools required.
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Thanks, very time appropriate for me. I've got to chase out a charging issue in my 04. With lots of load (heat, lights, seat heater) under throttle everything is fine, off the throttle and hit the brakes and there is a noticeable dimming of the lights, but then it recovers. The lag is too long and not normal. The battery is new, so I was thinking alternator / voltage regulator or belt tensioner, or maybe the belt itself.
Fleet Owner
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Could be your idle control isn't responding fast enough and not an issue with the alternator at all.
Fleet Owner
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When you take you foot of the gas and the lights dim, does your RPM gauge drop and rise along with the dimming effect?
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Not sure, I'll give it a look tomorrow night on the way home, unless it's a short day because of the snow coming in and I go home in the day light. Thanks for the help.
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Posting Guru
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Rpm's don't seem to move with the dimming while moving Typical situation is 40mph, on throttle at 1300 rpm, off throttle it drops to 900, lights dim then come back up with no change in rpm. Come to a stop and the RPMs go to 700 and the lights stay dim.
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