Hummer H-1

I have Hummer H-1

For the past few years I have a problem which no one knows how to fix.

There are 2 Hummer dealers in South Florida, but both of the gave up.

My Hummer dies suddenly while driving.

Everything shots off; ingine, horn, brakes, lights, but when it happens radio comes on, even if it was off before.

It usually dies when I down-shift before stop light or on the left turn, it never happens on right turn. Now it dies when I shift to “park”.

Dealers changed: batteries, alternator, main cable, fuel pump, some electronic components but no changes.

They even called GM ingeneer, he sugested to "rip off all the wires from the truck and replace it at the cost of $20.000.00, but even after that he could not warranty it will solve the problem.

Can you help?

Thank you,


My ph. # 305-632-5838

It sounds to me there is a intermittent connection within the main power buss or possibly the ignition switch areas. The main grounding wires need to be checked also.

You may be able to find the trouble area by tapping on suspected trouble areas with a screwdriver handle or by pulling on wire connections and see if the problem occurs. You may want to have a shop that specializes in electrical problems look at this. They should be able to figure out the trouble within a reasonable time frame.

I suggest that the first thing you do is get a copy of the electrical schematic for your vehicle and try to troubleshoot the problem yourself. It appears that the dealers are taking a “shotgun” approach that is costing you a lot of money. If Haynes publishes a manual for the Hummer, get one; their electrical diagrams are accurate and easy to read.

Start by studying the wiring diagram beginning at the ignition switch and trace the connections to every electrical part that is affected. Be sure to note the position of the switch contacts when the vehicle is in its normal running mode. Note for each part if it goes off or on when the problem occurs. Determine what electrical connections, including those made or broken, would cause the exact condition you describe to exist. Determine if only one component could be the cause. Put that component on your list of suspected bad parts to be tested further or replaced.

By the way, has this problem generated any codes? If so what are they? If you haven’t had the codes scanned, you should do so as soon as the problem reoccurs. Because this is an intermittent problem, it might be useful to acquire a small hand-held scanner and leave it connected as you drive the vehicle. Write down any codes that appear.

With a list of codes, you can take them to your dealer for interpretation, or publish them here; a number of the regulars here can interpret them for you.

Good luck and let us know what you find.