hmmwv starting/cranking problem

[chuckh]

Hello

My truck has decided to not start. While trying to start after it is warm it does nothing as if the battery is dead. The wait lights blinks (as normal when hot) and then nothing from the starter. It might be the switch. It will crank after sitting for a while.

This has happened before and I checked all the grounds and thought that took care of the problem but it has done it again.

Any ideas?

Chuck Herbert

[J8HN]

Just make sure the batteries are good. You must have at least 18 volts to to start. You may have one battery, that might be bad or going bad.

[Al Foley]

Check the nuteul switch, sounds dumb but wriggle the shift lever

1942 GPW Script
1944 GPW
1951 M38
1986 1025 HWWMV

[chuckh]

I don't have one. I put in a 4l80e overdrive unit.

thanks

Chuck

[HG]

Chuck, you can "S&T" it....
Take a windshield hinge pin clip and remove it from it's wire. Use this clip on your remote start terminal near the gearshift lever(under the round cap) connecting the "S" and "T" terminals (holes). Be sure truck is in neutral.

[Kurt Lesser]

Chuck,

The neutral starrter switch is mounted on the side of the shifter, not on the transmission so it could still be your problem. The other thing that could be happening is the Protective Control box could have a bad solenoid in it. There is a large solenoid that looks like a starter solenoid that's used to detect when the batterys have been installed properly to prevent damage from batterys being installed backwards. It could be dropping out when it gets warm and them remaking after it cools down.

The only real way to test it is to exchange the PCB with one you know is good.

The problem could certainly be in the switch but they usually don't act that way. If you have a meter you can chase some signals on the STE-ICE connector plug to see if the start signal is getting to the motor or you can have someone go under the truck while you turn the switch to see if there is 24 volts getting there.

[M996]

"I put in a 4l80e overdrive unit."-Chuck

Chuck,
Sorry your truck won't start but can you tell me more about your 4L80e conversion, such as needed parts, sources for those part and what mods were needed? Was it expensive, or can it be done for a reasonable price? I switched to radial tires and that improved performance, but I like the idea of park and overdrive. Please post the details of your tranny swap to help us novices.
Thanks

[chuckh]

When the 4L80e was installed the neutral safety switch was left out and bypassed.

The truck started first try this morning after sitting all night.


Chuck H

[D Pizzoferrato]

Chuck,
Had the same symptoms with mine some time ago. I hoped it was the switch as that was the simplest fix ( I knew that it probably wasn't the problem). Suspected the PCB as Kurt suggested. Finally replaced the PCB and cured the problem. Good luck, arent HMMWVs fun

[chuckh]

On the 4L80e.

The parts are readily available. You have to shorten the rear driveshaft nd install the computer for the trans. The computer is 12 volt so it is connected to one battery. I have a list of all parts involved for those interested. The new trans improves the truck very much. It cruises at 55mph with no strain on the engine at much lower rpms.

Looks like I will be replacing my pcb. What is the best version?

Chuck H

[Kurt Lesser]

Chuck,

There are probably half a dozen models of the PCB floating around right now. The one to stay away from is the LAU Technologies boxes with the seperate glow plug harness. That was the one that would randomly crank the vehicles and caused all kinds of problems. It was suposedly fixed with a design change but why take a chance?

Some of the newest and best seem to be the KDS series boxes of which there are 2. The green tag models have to be mated with a matching glow plug controller on the water crossover pipe, the yellow tagged boxes don't use the GPC at all and have proven to be very reliable.

I actually have an old Prestolite box in mine that has never given me a problem. It's the one that was in the vehicle when I got it and was most likely the one installed in the vehicle originally. There's no signs of it ever being changes that I can see.

You can find them on ePay all the time or get them from any of the HMMWV parts dealers. It really depends on what you want to pay for one and how fast you need it.

[Action]

Are you sure it is the yellow label that doesn't need the temp sensor in the crossover pipe? I thought it was the green label that didn't need it.

When is the wait light supposed to blink? My light comes on when the engine is cold and not, if the engine is warm. It has been like that since I put in the KDS yellow label with the KDS temp sensor. If I unplug the GPC plug from the temp sensor, then the wait light will blink when the key is turned.
Jason

[Kurt Lesser]

Action,

Now that I think of it I believe you're correct. I was thinking the yellow tag was the newer one. Anyone else know for sure?


I think Chuck may be referring to the wait light cycling during cold starts rather than actually blinking. You're right that it doesn't come on when the engine is already warm. Is this correct Chuck?

[chuckh]

My wait light functions properly. It stays lit for a few seconds when the truck is cold. When It goes out I start the truck.

When my no start problem occurs the truck is always warm. The wait light blinks for a milisecond which is normal but nothing from the starter when attempting to crank.


By the way my headlights will shine brightly when this happens so I don't think its he battery. After sitting for awhile it starts right up. Best starting truck of the 3 I have owned

Chuck H

[Ozhumvee]

I've got the latest SSI box in mine, had it about a year now and it works well, no GPC or Temp sensor required.
NSN 6110-01-491-2152