1987 Chevy Suburban engine dies when headlights turn on

Tiny
BURKEORAMA
  • MEMBER
  • 1987 CHEVROLET SUBURBAN
  • V8
  • 4WD
  • AUTOMATIC
  • 135,000 MILES
1987 5.7 Suburban 4x4. The truck has been running rough and cutting out the past few times I have driven it. The other day I turned on the headlights and the engine instantly died. I restarted the car with the lights off and it ran fine. When I got it home I turned on the headlights and the engine died again. I restarted and repeated the process with the same outcome, lights on; engine dies. The next day I had trouble starting the engine and suddenly the starter would not engage at all, no click. Nothing. I turned off the the vent fan, which I noticed was running and the starter would now engage. I cranked the engine a bit before it fired up but it would barely stay running and I had to keep the revs up to keep it going. I got the car to the garage and as I pulled in the garage, the engine smoothed out and it idled without any misfiring. So, I turned on the headlights and the engine kept running. I shut the car off, restarted it right back up, turned on the lights and it kept running. I shut it off, left the headlights on, resatered it and it fired right up and ran smooth as silk even as I flipped the headliths on and off repeatedly. What the heck? Any ideas?
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Monday, December 1st, 2008 AT 12:48 PM

4 Replies

Tiny
JAMES W.
  • MEMBER
There are only 2 things I can think of that would caues this problem. Neither of which can be checked unless the condition exists. 1-low battery charge, which I doubt, and 2, bad body control module. From there it could go to a bad ground and expand from there. You sure don't want this to happen in the middle of the night. I realize I haven't helped you much, but time will tell.
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Monday, December 1st, 2008 AT 2:08 PM
Tiny
BURKEORAMA
  • MEMBER
Thanks for the reply James. I was kind of expecting a grounding problem but the symptoms seem so strange. I might add, when I tried to turn on the headlights and the engine died, the lights did not come on at all. They were completely dark. Also, after turning off the ignition, the lights still would not some on at all. It was like the entire electrical system shorted out when the light switch was in the on position. Now it works fine, but, I'm sure it will rear it's ugly head at just the wrong time. You are right that I don't want the car to fail at the wrong time. We keep this car at a vacation home in very remote location by Lake Mead in the Arizona desert and a breakdown could mean roasting to death in the summer or freezing to death in the winter!
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Monday, December 1st, 2008 AT 4:43 PM
Tiny
BURKEORAMA
  • MEMBER
One other thing.
I don't believe that a 1987 Suburban R20 4x4 has a BCM. Any other thoughts?
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Monday, December 1st, 2008 AT 5:27 PM
Tiny
ROADSTER1929
  • MEMBER
It could be the gound that goes from the battery to the engine. I had that problem. Also nmake sure your engine is gounded to the body or frame
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Monday, December 1st, 2008 AT 5:39 PM

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