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Jerry, Master Mechanic
Category: Car
Satisfied Customers: 17220
Experience:  ASE master, 30+ years. All makes and models. Trouble shooter, shop forman, service manager
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Super: 1990 mit montero Ls 3.0 6cyl..idling

Resolved Question:

Hey super mechanic, dead on for the trans temp switch, it stays on even when vehicle is cold. Anyway I have another question for my 1990 mit montero Ls 3.0 6cyl. When vehicle is at stop, idling in drive, with a.c. on, head lights on (driving @ night), wipers on ( raining summer), and turn signal on, volt gauge starts to drop and lights go dimmer and if i sit long enough turn signal indicator in vehicle stops blinking. I have replaced the altenator, and as soon as i take off volts rise again and so on, this one has been driving me crazy
Submitted: 8 years ago.
Category: Car
Expert:  Jerry replied 8 years ago.

I have had that same problem on some of my own, Embarassed (I didn't want to spend any money, raising 2 kids) and rather than buy a higher output alternator, I would turn the idle up just a little.


You will want to make sure that the belt is tight, (duh) if you have not already.

Then, sometimes the alternator may test good, (either on the bench or in the vehicle) but the actual load that is put on it when the car demands it might be causing the amps to go low and then eventually the volts will follow.


If the idle seems a little low, you might want to just tweek it up a bit. Belt tight, (not glazzed too too bad) and the correct alternator for the application, should be good to go.


If not, then you might want to see if there is a higher amperage for that application.


Oh...also a good fully charged battery....

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