My dad calls me this morning saying that his 2000 GMC will start and immediately stop. He tried it multiple times with the same results.

I know on older cars with points, there is a bypass in the starter to pass current to the ballast resistor to give the coil full voltage during cranking. Sometimes that would cause problems exactly like this. But there can't be anything like that on these new trucks, right?

Anyone have any ideas?

 

Like it starts and revs up and dies? If that's it it might be the VATS system.

 

does his security light stay lit or flash like its supposed to? If so, it could be that the ecu or bcm (dont remember which) isnt sensing the resistance that its supposed to from the ignition (key hole thingy). If that were the case it would most likely mean a bad key hole thingy (ignition module?).

 

Didn't mention anything about revving up. I'll ask some more questions when he gets off work. VATS sounds like a real possibility. I thought they ran about 15 seconds before dying with the VATS.

 

When I did my PCM swap it would do what I said....start, rev up to like 1200 RPM like it normally does, then instead of dropping back to idle speed it would just die. Did that until I did the security relearn.

 

I should be able to search for that security relearn huh?

 

Yeah there's a writeup somewhere on how to do it, I don't remember off-hand.

 

This looks like the thing, I'll send him the link and see if it helps.

http://www.nelsonperformance.com/passkey.htm

 

Mine does that every once and awhile , sometimes at a stop sign to . But I can keep it running if I push the throttle down a little more than before & use the brake to keep the rpm's up at stop signs . Dont know what the deal is .

 

If it immediately dies out no more than one second after it turns over, it's very likely to be VATS related. Bad switch may be cause, or it just may need to be relearned.