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Alternator not coming on

Tiny
JACK COLMYER
  • MEMBER
  • 1996 CHEVROLET BLAZER
  • 199,000 MILES
My vehicle has been through two alternators and two batteries. My alternator just will not kick on. I just did a motor swap (same engine 4.3l) everything runs good just alternator. My battery light does not come on either. Over heard that could be the problem in the past but I do not know. I need some help.
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Saturday, October 20th, 2018 AT 4:37 PM

11 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi and thanks for using 2CarPros.com.

Does the problem happen while the engine is running or only after it sits over night?

Do me a favor. Go through this link and tell me the results. It will require you to use a volt meter. Here is a quick link related to using one:

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Here are the directions for testing the alternator. Do this and let me know the results.

https://www.2carpros.com/articles/how-to-check-a-car-alternator

I did check for technical service bulletins related to the alternator/charging system, but there was nothing listed.

Let me know the results. Also, make sure the ground to the engine block is clean and tight as well as all battery cable connections.

Take care,
Joe
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Saturday, October 20th, 2018 AT 6:07 PM
Tiny
JACK COLMYER
  • MEMBER
  • 7 POSTS
Thanks, I have done all the basics bought a volt meter it does not do nothing but drop in volts until the battery is at around 10 volts. Then truck idles really low until I cut it off and then it just clicks as the battery is dead. I have took my ground off once before and cleaned it I think my connections are good just alternators not kicking on.
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Sunday, October 21st, 2018 AT 6:40 AM
Tiny
JACK COLMYER
  • MEMBER
  • 7 POSTS
That is why I was asking about the gauge cluster. Battery light it does not come on ever as if I do not have one.
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Sunday, October 21st, 2018 AT 6:41 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Welcome back. If the alternator is good and not producing current, then it either is not getting power supplied to it or the is an open between it and the battery. Since the light is not turning on inside, I suspect the open may be between the alternator and battery. Have you checked for a faulty fusible link?

Take a look at the schematic listed below. It shows all of the for the starting and charging system. The first one I would check is the 12ga-blue one between the alternator and battery. Check it for continuity. If it is good, confirm that the power from the starter (also a fusible link) is good. I had to break the schematic into two pictures.

Let me know if this helps.
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Sunday, October 21st, 2018 AT 5:11 PM
Tiny
JACK COLMYER
  • MEMBER
  • 7 POSTS
Okay, so the 12g wire is good I suppose, it has 12 volts at the alternator stud I changed the smallest wire fusible link with a inline 30 amp fuse still nothing alternator wont kick on I need someone to maybe face-time sometime tomorrow and help me thanks
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Tuesday, October 23rd, 2018 AT 3:49 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Welcome back:
What I need you to do is this. If indicator lamp is not on, disconnect wiring harness at alternator. Ground "L terminal using a fused 5 amp jumper wire. If lamp lights, replace alternator. If lamp does not light, check for a open between the grounding lead and the ignition switch.
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Tuesday, October 23rd, 2018 AT 5:50 PM
Tiny
JACK COLMYER
  • MEMBER
  • 7 POSTS
So all fusible links are good is there any more beyond this and what di you mean wire harness is that that 3 point connector only other plugs I have is a actual plug wit one wire going into it
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Wednesday, October 24th, 2018 AT 3:56 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
The wiring harness going to the alternator. As far as the system, here is a schematic of the entire system. Something isn't making good contact. For example, you may show continuity with a meter, but when a load is placed on something like a ground, it may still fail.
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Wednesday, October 24th, 2018 AT 6:20 PM
Tiny
JACK COLMYER
  • MEMBER
  • 7 POSTS
I dontthink I have that brown wire is that a bolt on one or the actual snap in plug wire because I think mine is red I'll look tomorrow after work and get back with you
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Wednesday, October 24th, 2018 AT 7:18 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Let me know what you find.

Joe
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Wednesday, October 24th, 2018 AT 7:42 PM

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