2001 Toyota Highlander electrical

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2001 toyota Highlander. Put on a new alternator, however this is a 100amp not 130amp. Car runs unless headlights or something else is turned on then it immediately dies. Is this because of the alternator not being 130amp or something else?

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Sunday, March 16th, 2014 AT 10:25 AM

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No. 100 amps is WAY more than any car needs. 130 amps is just what was used on yours because if all the right conditions were met, it might be possible to need that extra capacity for a few seconds. Under normal driving conditions about the most any newer car with all its unnecessary computers needs is about 35 - 40 amps. It takes ten amps to run a pair of head lights, eight amps to run the fuel pump, etc.

What you're describing can have a few different causes, but it shouldn't be related to just the generator. First of all, it has six diodes, and if one of them fails, you will only be able to get exactly one third of it rated capacity, in this case, less than 35 amps. That may not be enough to run the entire electrical system under all conditions, but the battery should easily be able to make up the difference for short periods. To stall the engine, either the generator isn't providing enough current, AND the battery is too weak to make up the difference, or the added demand on the generator is loading down the engine causing it to stall.

Stalling due to the added load would only occur at idle and the automatic idle speed system isn't responding properly. That can even be caused by disconnecting the battery, which needed to be done to replace the generator. On many cars the Engine Computer has to relearn when to be in control of idle speed, and meeting the conditions for that relearn to take place generally involves a few simple steps during normal driving.

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Wednesday, March 19th, 2014 AT 2:16 PM

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