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1990 Mercedes Benz 300e

Tiny
HGREEN12
  • MEMBER
  • 1990 MERCEDES BENZ 300E
Electrical problem
1990 Mercedes Benz 300e 6 cyl Two Wheel Drive Automatic

alternator tested bad, bought another, tested good but when I turn on lights it would test bad. What are your thoughts?
Thursday, February 12th, 2009 AT 8:34 AM

2 Replies

Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
I have forwarded your link to our resident M/B expert. He should be with you shortly

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Thursday, February 12th, 2009 AT 8:55 PM
Tiny
GFIMOTORCARS
  • MECHANIC
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I just want to be sure we are clear about your test. So what you saying is when you place the vehicle under a load (lights on) the alternator is not increasing output to meet demand of more components. If this is the case you may have a faulty replacement alternator (this does happen) or a faulty voltage regulator within the alternator. The voltage regulator is a more common issue on MB vehicles. When you are testing this are you checking volts or amps? What are your readings like? Where are you testing, how do you have the meter hooked up? Also is the part a Bosch alternator or is it an aftermarket brand?
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Friday, February 13th, 2009 AT 10:16 AM

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