transmission shift issue

[street legal humvees]

we are hoping to get some guidance on an issue about to drive us nuts we are finishing an m1123 overhaul and after fuel issue nightmares, we thought we were home free but the the trans will operate only in reverse and in first , and of course no dice on testing codes as we don't have a J1 6 pin connector (we found a really cool post detailing how to make one using an old gm port , but just ordered the parts so not here) / [FONT=arial, sans-serif]We [/FONT]had a couple tcm in shop so changed out and no difference in fact we ran truck w tcm disconnected and it runs the same ! is this limp mode ? any ideas as to whether a [FONT=arial, sans-serif]bad solenoid or speed sensor could be the issue / also my understanding of these tcm is that they are plug and play since the problem exists no change w 2 diff tcm and even w tcm NOT connected could it be wire harness any suggestions ? we are at wits end !!![/FONT]

 

[Action]

Is that a 4 l80e with military TCM? Properlycheck the trans fluid level. It sounds like it is stuck in limp home mode. You can check trans codes with a paper clip.

 

[street legal humvees]

yes it is a4l80e we just changed filter and replaced the fluid 5 pints reads full / military tcm /how is it u check codes with a paperclip that trick there would be valuable knowledge please enlighten me !!! thx
anything else cause limp mode ?

 

[street legal humvees]

5 pints sorry

 

[Action]

5 pints sorry

TM lists 4l80e drain and refill is 7.7 QUARTs. I think you may be a bit low on fluid which would cause your issues.

 

[Retiredwarhorses]

Works In reverse and 1st....it’s in limp mode. call our shop if you would like some further assistance

 

[Action]

..

 

[BestPrez45]

Works In reverse and 1st....it’s in limp mode. call our shop if you would like some further assistance

Howdy, It's Saturday and I am reading this message. I literally have the same issue as the fella who initiated this thread.
Replaced my fuel pump and couldn't get the the humvee over 35mph. Thought it was fuel related but it turns out the trans is not shifting out of first. The light on the "tunnel" next to the gear shift did not blink so "limp home" mode was not thought of at first but now after reading this thread and several others, it must be the same issue I'm having. Would it be possible to contact you on monday to talk about this? I'm not a mechanic but maybe I can relate some information to the shop that is working on it for me. Good guys here in AZ but not much experience with this vehicle.

 

[Mogman]

Howdy, It's Saturday and I am reading this message. I literally have the same issue as the fella who initiated this thread.
Replaced my fuel pump and couldn't get the the humvee over 35mph. Thought it was fuel related but it turns out the trans is not shifting out of first. The light on the "tunnel" next to the gear shift did not blink so "limp home" mode was not thought of at first but now after reading this thread and several others, it must be the same issue I'm having. Would it be possible to contact you on monday to talk about this? I'm not a mechanic but maybe I can relate some information to the shop that is working on it for me. Good guys here in AZ but not much experience with this vehicle.

 

[BestPrez45]

Thank you thank you thank you, for this. And I did I mention thank you?