New Humvee Owner - Transmission question

[JDHouseman]

Hello,
I'm new to the humvee world, having picked up my 2001 1097 a few weeks ago. I noticed it's having issues when I stop at a stop sign, usually on an incline, reengaging the transmission. It was throwing off transmission codes 38 and 85. After some study, I determined I should replace the brake light switch. That fixed both of those codes, however the issue with engaging remains and code 37 now appears. I'm wide open to suggestions on this. It's an otherwise great running and great condition rig, so the transmission issue is driving me crazy!
Thanks in advance for any assistance.
Pics attached. I painted it, added new seats, top and doors... just need to get it running 100%!

 

[Mullaney]

Hello,
I'm new to the humvee world, having picked up my 2001 1097 a few weeks ago. I noticed it's having issues when I stop at a stop sign, usually on an incline, reengaging the transmission. It was throwing off transmission codes 38 and 85. After some study, I determined I should replace the brake light switch. That fixed both of those codes, however the issue with engaging remains and code 37 now appears. I'm wide open to suggestions on this. It's an otherwise great running and great condition rig, so the transmission issue is driving me crazy!
Thanks in advance for any assistance.
Pics attached. I painted it, added new seats, top and doors... just need to get it running 100%!

.
Welcome to the Outfit and THANKS for the pictures too!

Page 33 in the attached PDF has the error codes.
7_4L80E Troubleshooting Guide...

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[cwc]

Are you saying that it acts like it is neutral and then engages when you give it some throttle? And regarding the incline, is it uphill, downhill or both?

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[Mogman]

It looks like you still have brake light switch problems, maybe the new switch is not adjusted correctly, not sure that will fix the "issue" but need to get that taken care of first. there are two parts of the brake light switch, one for the brake lights and one for the transmission, you cannot tell about the transmission side of the switch without using a meter.

 

[cwc]

If the shifter is in a forward position, the forward clutch should be engaged and the transmission should be engaged in a forward gear. From a stop, it should be first gear, or second if the controller is not powering the solenoids. Engagement with a jolt when rpm is raised (if that is what is happening) suggests the forward clutch is dropping out and then engaging. It could be low fluid level, the filter connection to the case sucking air, or low apply pressure. Low pressure could be a clogged filter, a pump problem, or an internal leak such as clutch piston seals. I would start with a filter change, making sure the filter seal is good, followed by line pressure check if the problem persists.

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[JDHouseman]

Are you saying that it acts like it is neutral and then engages when you give it some throttle? And regarding the incline, is it uphill, downhill or both?

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It acts like it's in neutral on an uphill incline. If I mash the brakes, it'll engage. So, I'm guessing there may isn't enough travel on the brake switch. Does that make sense? Is there any way to adjust that? I have to barely touch the pedal to get it to stop, so it could afford to loosen up.

 

[JDHouseman]

If the shifter is in a forward position, the forward clutch should be engaged and the transmission should be engaged in a forward gear. From a stop, it should be first gear, or second if the controller is not powering the solenoids. Engagement with a jolt when rpm is raised (if that is what is happening) suggests the forward clutch is dropping out and then engaging. It could be low fluid level, the filter connection to the case sucking air, or low apply pressure. Low pressure could be a clogged filter, a pump problem, or an internal leak such as clutch piston seals. I would start with a filter change, making sure the filter seal is good, followed by line pressure check if the problem persists.

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Thanks for this. I'll change the filter and see if that makes a difference. I think the brake switch is still not doing its job, but will try changing the filter as well.

 

[JDHouseman]

It looks like you still have brake light switch problems, maybe the new switch is not adjusted correctly, not sure that will fix the "issue" but need to get that taken care of first. there are two parts of the brake light switch, one for the brake lights and one for the transmission, you cannot tell about the transmission side of the switch without using a meter.

Thanks. I bought a meter, so will have to give that a shot. The new switch does operate more smoothly than the original, but I think there's just not enough play in the brakes.

 

[Mogman]

Did you get this resolved? if so what was the issue.

 

[JDHouseman]

If the shifter is in a forward position, the forward clutch should be engaged and the transmission should be engaged in a forward gear. From a stop, it should be first gear, or second if the controller is not powering the solenoids. Engagement with a jolt when rpm is raised (if that is what is happening) suggests the forward clutch is dropping out and then engaging. It could be low fluid level, the filter connection to the case sucking air, or low apply pressure. Low pressure could be a clogged filter, a pump problem, or an internal leak such as clutch piston seals. I would start with a filter change, making sure the filter seal is good, followed by line pressure check if the problem persists.

Sent from my motorola one 5G UW ace using Tapatalk

I just wanted to thank you for this response. I changed the transmission filter this morning and experienced zero transmission issues all day today... she shifts like a champ! Changing the filter was a real pain in the ass, but I like solution much better than the alternatives!

Thank you again. I greatly appreciate this site and the wisdom of the contributors.

 

[frauhansen]

But one more thing as a supplement on the subject of brake light switch and transmission signal with the 4-speed.

There are two switches, operated by th brake pedal by only one smale "z"-fomed pice of wire.
Couse of the short movement that the brake pedal makes on this rigs it is very very hard to adjust this switches in this way that both deliver the signal to the brake lights AND the gearbox at the sme time.
In reality you have a correct signal to the gearbox but no or permanently brake lights or the oposide way.

Solution i made for myself... disconnect the switch for the gearbox. Arjust your brake light switch correctly. Grab the signal for the gearbox by using al relais on the 24V brake light power directly at the switch on the pedal.