Wait light turns on at odd times. Please help.

Hummer H1 and Military Humvee topics
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Posts: 3
Joined: Mon 28 May , 2012 1:06 am
hummer_info: 1997 open top

Wait light turns on at odd times. Please help.

Post by joe97hummer » Mon 28 May , 2012 10:58 am

I am the new owner of a 1997 H1 open top. This beast was rotting in the back 40 when I bought her. Aired up the tires and towed her home. Replaced the transfer case, repaired the brakes and bought two new batteries. Once running I noticed the wait light cycles at odd times and that the engine was shot. I replaced the cracked block (water in the oil) with a military takeout long block. I was getting an occasional p0236 and no boost noise so, based on the website (great resource), I checked the vac pump (25in of vac - good) and I replaced the pressure sensor and the boost control solenoid. Boost now works. Everything else appear to be working properly, not completely sure since this is the first hummer I've owned.

The problem:
Cold start, ambient temp = 75F (Hawaii): No wait light but I can hear the glow relay cycle on and off for a couple seconds. The Check engine light is on but clears as soon as the truck starts. The throttle warning light goes one for half a second and then stays off - appears to be part of a light check. I wait to start the truck until I hear the glow plug relay cycle off. Truck starts immediately.

Truck warmed up: The wait light turns on and off in a predictable manner but I don't understand why. The predictable part is:
1) Highway - coasting down = no light
2) Highway - tip in to moderate throttle = constant light
3) Highway - full throttle = sometimes the light will go out
4) Stop light - idling = no light
5) Accel from stop light = no light until moderate speeds then light behaves as described on the highway

Mods: Remote PMD and #9 resistor. Ran the same when running the old PMD in the stock location with presumably the stock resistor - retired in place. Well, not exactly the same - no more mysterious stalling. The wait light operated the same. I am using the hmmwv turbo and wastegate and the stock wastegate control system.

It drives perfectly (except the annoying wait light)

Any ideas what is going on? I am concerned since I am going to ship this truck to the mainland and drive it in diverse climates.

Posts: 3
Joined: Mon 28 May , 2012 1:06 am
hummer_info: 1997 open top

Re: Wait light turns on at odd times. Please help.

Post by joe97hummer » Tue 29 May , 2012 3:35 am

Update: The wait light turns on when the tranny shifts into 4th. I figured this out as I was trying to determine when it turns on driving around town. Does anyone know why it would do this?

Checked some of the geared hub oil levels for the first time since I bought it. One was nearly empty and what little drained out looked like muddy water so I pulled off the cover to wipe out the hub before refilling. The cover was so corroded on one side I am sure I wouldn't be able to make it seal every again. Argh. It takes so long to get hummer parts shipped here, so I decided to fabricate my own cover plate. Not only was it fun to make but it worked. Unfortunately, I discovered why the hub was nearly empty, both seals leak. Now I have to wait until I can get new seal shipped to me. One step forward, two steps back. I wonder what else is wrong with the hub besides the seals.

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hummer_info: 1998 H1
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Re: Wait light turns on at odd times. Please help.

Post by chuck » Fri 01 Jun , 2012 8:26 am

The problem you have is that the truck was sitting out in a humid atmosphere where about every electrical connection and ground could be compromised. The truck's aluminum body means that the grounds are all run in copper wires. I'd start checking all the connectors and grounds I could find. Maybe it's a bad connection in the glow plug circuit or glowplug controller. Check all the grounds under the dash where the gauges are all grounded. I have an article about that in the tech section.

I'd order another set of hub seals to have as spares.
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