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Charging system

Tiny
CRASHMAN1VESTAL1962
  • MEMBER
  • 1999 CHEVROLET S-10
  • 4.3L
  • V6
  • 2WD
  • AUTOMATIC
  • 216,000 MILES
New alternator and new battery. Before starting volts read nine volts on gauge. After starting takes about eight miles before gauge gets up to twelve plus volts. Turn on lights or heater volts drop back to nine. After driving awhile system might get back up to twelve plus volts
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Friday, February 3rd, 2017 AT 7:19 PM

6 Replies

Tiny
CARADIODOC
  • MECHANIC
  • 33,871 POSTS
Measure the voltage on the large output stud on the back of the generator while the engine is running. Also, measure the voltage on the brown wire in the connector at the back while the engine is running. That has to done by back-probing through the connector while it is plugged in.
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Friday, February 3rd, 2017 AT 7:21 PM
Tiny
CRASHMAN1VESTAL1962
  • MEMBER
  • 4 POSTS
Battery unhooked 12.6. Back of alternator 14.3 born wife 4.07.
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Friday, February 3rd, 2017 AT 7:41 PM
Tiny
CRASHMAN1VESTAL1962
  • MEMBER
  • 4 POSTS
Alright one more time crazy spell check. When I unhook the battery it shows 12.6. With the truck running on the post on the back of alternator 14.3 on the plug in 4.07.
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Friday, February 3rd, 2017 AT 7:44 PM
Tiny
STEVE W.
  • MECHANIC
  • 13,443 POSTS
If you are seeing 12.6 on the battery and 14.3 while running the system is charging. Are you having trouble starting the vehicle? It sounds like you may simply have a bad stepper motor in the dash. Take a voltage reading from one of the power outlets/ cigarette lighter inside the vehicle. What is that voltage engine off and engine running?
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Friday, February 3rd, 2017 AT 9:31 PM
Tiny
CRASHMAN1VESTAL1962
  • MEMBER
  • 4 POSTS
I went to the cigarette lighter 12 volts key off 12 volts engine running.
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Saturday, February 4th, 2017 AT 6:26 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,513 POSTS
Its sounds like the gauge in the dash is bad or you have a bad connection in the PDC.

Please check it out and get back to us

Best, Ken
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Wednesday, February 8th, 2017 AT 3:02 AM

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