Why does the engine die when I plug the alternator in?

Tiny
EXGI
  • MEMBER
  • 1988 BUICK CENTURY
  • 75,000 MILES
88 Buick Centry 2.5 TBI starts and dies, unplug the alternator and it starts and runs Ok. Plug the alternator 3 wire connector back in and the engine dies. Voltage starts to increase when alternator is plugged in before it dies. IAC seems to to be working because it adjusts engine speed when A/C is turned on. Why does the engine die when the altenator is plugged back in, what am I missing?
Monday, August 13th, 2012 AT 2:19 AM

8 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Computers hate voltage spikes and thats what you are doing. Dont ever do this again as you will burn out modules.

Why are you doing this? What issue do you have

Roy
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Monday, August 13th, 2012 AT 2:30 AM
Tiny
EXGI
  • MEMBER
  • 4 POSTS
Why does it start and die with the alternator connected? The alternator has been replaced, battery swapped, ECM swapped and still does same. Runs with alternator disconnected, starts and dies when it's connected. Old pro link connected up, ECM shows 14, 4 volts when it dies. Has no fault codes.
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Monday, August 13th, 2012 AT 3:15 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Did you use a used or rebuilt alternator?

Roy
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Monday, August 13th, 2012 AT 10:07 AM
Tiny
DJCL
  • MECHANIC
  • 767 POSTS
Check the alternator riple. To much ac voltage out of the alternator will do that
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Monday, August 13th, 2012 AT 11:55 AM
Tiny
EXGI
  • MEMBER
  • 4 POSTS
It's a rebuilt alternator from Auto Zone. The old alternator did the same thing as the new one, no difference.
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Monday, August 13th, 2012 AT 12:55 PM
Tiny
DJCL
  • MECHANIC
  • 767 POSTS
Is the charge lamp working
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Monday, August 13th, 2012 AT 11:15 PM
Tiny
EXGI
  • MEMBER
  • 4 POSTS
Yes, the charge indicator light is working.
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Tuesday, August 14th, 2012 AT 11:29 AM
Tiny
DJCL
  • MECHANIC
  • 767 POSTS
Have that alternator tested on the car for ac ripple. Whar is the ac volt in milly volts reading
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Tuesday, August 14th, 2012 AT 12:38 PM

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