I have a 2001 Suburban 1500 LT. 82,150 miles. My car shuts off with no warning when traveling over minor bumpy roads. It's as though someone just took the key and shut off the car. I can usually restart on the roll in neutral but other times I have to stop the car completely. So far I have changed the ignition wiring harness, the crankshaft position sensor and 1 week ago a new fuel pump. Still no luck. I'm going nuts. Any ideas?

 

Check your battery cables especially the ground cable.
Do you have a bunch of keys on your key ring?

 

I only have the one key and it appears that the battery cables are fine. I'm not sure where all of the grounding points are on the car to check. thanks

 

Its likely shutting off due to voltage loss... a running vehicle will remain running with the battery disconnected so keep that in mind as you troubleshoot
Check the connections at the under hood fuse box as well...

 

Where would the voltage loss be? To the ignition? The car just shuts off as if the ignition switch was turned off. Thanks

 

check that your main positive battery cable is not loose at the starter.also check the battery ground cable at the engine block.i have come across a few lcables to the starter and grounds on the engine block that were loose and cause the issue your having.hope this helps you out.

 

My 01 would shut down running down the road after bumps and I chased and chased it. Ended up pulling the cluster out and running new grounds there and it quit dying. You may check that. Mine would shut off and come right back on sometimes and other times it would take awhile before it would refire.

 

Are you saying that the ground connection behind the dashboard ( "cluster" ) needed improvement?

 

Yes, I can't remember if I came across the idea on a forum or if one of the techs at my dad's gm dealership suggested it, but I want to say it was a fairly common issue.

 

Thanks so much for all of the help. Just got back from my home in Cabo San Lucas, Mex. Finally got to look at the truck and sure enough the ground from the instrument cluster grounded to the right rear of the engine block which that was spliced with another wire came apart at the grounding point. We re-attached the two wires together as well as a new connector and grounded it to a better position on the block and, knock on wood, problem fixed for now. Thanks again.