Car dies when going down the road with AC on then runs again

[Billiumss]

A friend of mine has a 1999 Grand Prix GT 4dr 50k miles.

 

Every once in a while when he is going down the road cruising with the AC on, the car will just die, the RPMs go to zero, all the dash lights come on and then 1-2 seconds go by, it starts back up on its own and everything is back to normal.

 

What in the heck would cause his car to do this?

 

There is no squealing coming from the engine bay, so we are assuming the AC compressor is not locking up. AC works fine.

 

No codes have been set.

 

Since it only has done it about 2-3 times in the past 4-6 months, driving around with a scanner all the time won't be possible.

 

What do you guys think?

[Casper]

Sounds like he has a car alarm with an engine kill and its acting up. Had the same thing happen to my on my 88 Nissan Pulsar (I was 16... it was a cool car for 16... bite me). The alarm had a shorted out wire. Every time that wire would make contact with a ground, the engine would just turn off. I'd hit a bump or something to cause the wire to move, and voila... my car ran again. Could be it. Might not. But its something to look at.

[Billiumss]

No aftermarket alarm, he bought it new.

[nathan]

I think it is still a ground situation though. Have you checked the various connectors going into the AC? It sounds like one is causing a short to ground that is affecting the ECM. Without seeing the wiring diagrams I would guess it is the clutch on the compressor that is the culprit, but that is just a guess.

[AJ]

bill, does the engine really turn off or are they just thinking it does because the tach shows 0 RPM? there is no way a car will start back up by its self let alone be in gear and restart. kind of sounds like a BCM problem, 1999-2001 were not good years for GM for BCM's. prolly has noting to do with the a/c being on just considence that it is when it happens.

[Billiumss]

All the lights come on the dash and then it restarts, he can feel it jerk during this.

[AJ]

per another tech here at work that has seen one do this. it needs a crank sensor.