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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15201
Experience:  GM Grand Master Technician 2007. 14 years experience.
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Chevy trailblazer: I have a 2004 Chevy Trailblazer 4.2L .I

Customer Question

I have a 2004 Chevy Trailblazer 4.2L .I have voltage drop at 2500RPM and up it falls to the point my batt light comes on ..when RPMs are below 2500 voltage is great holds at 14.6

Submitted: 2 years ago.
Category: Chevy
Expert:  Gary replied 2 years ago.
I am sorry for the long waiteverything you did so far was to correct this issue and nothing made it any better or worse ?
Customer: replied 2 years ago.

not everything the new Alt is a high output 250amp ..Alt is Good had it bench tested but the replacement of the belt tensioner was to correct the problem and the pully on the new alt is smaller than factory but I bought a shorter belt oem belt is 915 new is 910

Expert:  Gary replied 2 years ago.
and it was doing this before any of that work was done correct ? it stopping to charge over 2500 rpm ?
Customer: replied 2 years ago.

not exactly with the old alt it would drop voltage when decelerating sometimes but not always and it would drop voltage when accelerating but not all the time it was intermittent but with the new alt I have no drop when decelerating and drop all the time when it gets to 2500rpm and above

Expert:  Gary replied 2 years ago.
the big power wire bolted to the alternator is clean and tight and the battery cables are clean and tight ?if so unplug the alternator electrical connector and there should be 2 wires and terminals in the connector with something small similar to a dentist pick tweak over the centers of the female terminals in the connector so they are just about closed off so when its plugged into the alternator you know 100 % both terminals are making a good connectionthen drive it and see if it still does this
Customer: replied 2 years ago.

yes....It's not a 2 wire Alt is a GM 4 pin