Intermittent shutoff problem

[Steven Petersen]

I’ve had this pickup about 14 months now. It’s recently developed a very intermittent shutoff problem. It’s always right after starting it, and it will always immediately restart. It’s only done it 4 times over about 2 months. No codes on the scanner. All grounds have been double checked. Is there a way to diagnose the ignition switch or should I just replace it?

 

[sntrym]

model? year? engine/transmission? any details about the truck would help diagnosis

 

[Steven Petersen]

model? year? engine/transmission? any details about the truck would help diagnosis

88 K2500 350 700R4

 

[kenh]

I’ve had this pickup about 14 months now. It’s recently developed a very intermittent shutoff problem. It’s always right after starting it, and it will always immediately restart. It’s only done it 4 times over about 2 months. No codes on the scanner. All grounds have been double checked. Is there a way to diagnose the ignition switch or should I just replace it?

Sounds like mine.... Did it again the other day. Driving down the road and just like to turned the key off. Fired up while coasting and away you go! Hard to fix something that's not broken!

Ken

 

[Steven Petersen]

Sounds like mine.... Did it again the other day. Driving down the road and just like to turned the key off. Fired up while coasting and away you go! Hard to fix something that's not broken!

Ken

Yeah, and the ignition switch is hard to get at. If I go in I’m changing it regardless.

 

[CrustyJunker]

I’ve had this pickup about 14 months now. It’s recently developed a very intermittent shutoff problem. It’s always right after starting it, and it will always immediately restart. It’s only done it 4 times over about 2 months. No codes on the scanner. All grounds have been double checked. Is there a way to diagnose the ignition switch or should I just replace it?

Is this behavior is on a cold start? Or after it's already hot?

 

[jaywestfall]

Yeah, and the ignition switch is hard to get at. If I go in I’m changing it regardless.

I had to have my key cylinder replaced, so I replaced the ignition switch at the same, too. Good idea!

 

[Steven Petersen]

Is this behavior is on a cold start? Or after it's already hot?

It’s actually done it cold and hot.

 

[kenh]

Is this behavior is on a cold start? Or after it's already hot?

Mine has never done it cold. Always running down the road. Completely random. That I can see none of the shut downs had anything in common except the engine was completely warm.

 

[CrustyJunker]

That's a tough one...This could be a bunch of different things. Trying to give ideas without the parts-cannon approach!

Wiggling the ignition switch would be the easiest way to make sure that isn't the problem. I know it sounds silly, but you don't let the key switch "snap" back after cranking, do you? ...Witnessed it before and gotta ask.

Best guess from me would say check your fuel pressure next, if that's good it might be the oil pressure switch or positive power related. I had both of these problems before, but I don't want to lead you on a wild goose chase.

@kenh : Yours almost sounds ignition related or power related? Spitballin' here...I've heard defective ignition modules getting hot sometimes zap out while cruising down the road. You guys got the tough problems!

I also had a bad fusible link once on a Vortec truck. If the computer loses power for a second, it stalls and all the dash lights come on. Restarts like nothing happened.

Tried to keep it short unless you want more details. Hope you guys figure it out!