4l80e limp? No shift out of 2nd m1165

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4l80e limp? No shift out of 2nd m1165

Post by RAS1 » Mon Mar 22, 2021 8:37 pm

Hi,
I know there are threads on this. I looked at them and still need suggestions before proceeding.

I have an m1165 6.5td with 4l80e trans. Test drive to about 30mph with engine screaming. I'm not getting it to shift out of 2. About 10k miles on humvee.

When manually shifting I can go from 1 to 2. While driving at what I feel is max speed of 30, I feel a very momentary shift when going from od to d. (Engine rpm changes enough to notice)(It is not in 3 or 4 (I have others that I drive and am sure this is in 2)

My trans light goes on at startup. Goes off after a few seconds.

I jumped a & e . Goes into diagnostic mode, but keeps repeating 12 (1 slow then 1 quick 1 quick) no other code is shown. I have tried right after driving without disconnecting battery.

I have another controller to swap out, I just dont want to ruin it

I can drop the pan, but want suggestions first

I also printed out 189 pages of the transmission manual. Helpful if I had a scan tool which I do not.

All plugs are plugged in on trans, tps, relay and breaker.

I have pushed in the breaker for a reset, but doesnt really move.

I have checked fluid level and condition. It is good.

Linkage shifts smoothly, comes right out of park and works well in reverse.

1 bolt was missing on the transmission pan holding linkage on. Looks like socket Mark's on pan bolts indicating to me pan has been off. Also wires on relay were "pulled" back to reveal conductor for what appeared to be a voltage test, so someone was having a problem.

My other issue on this truck was a low compression motor, which was a no start. I swapped engines. I just find it hard to believe both the engine and trans would both catastrophically fail at the same time.

Someone mentioned a ste/ice connector that had no power causing his limp mode issue. But I also believe his transmission lamp wouldn't light.

Any help would be appreciated.

Ty
Dave


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Re: 4l80e limp? No shift out of 2nd m1165

Post by Ted Gates » Tue Mar 23, 2021 7:39 am

An easy first thing to do is swap out the TOSS with the TISS. They are are black sensors on the drivers side of the transmission. The TISS (forward most one) is not used in humvees and can be used as a TOSS (Aft most one) replacement. A bad TOSS will cause limp mode, but so does other things...but at least you know it is or isn't something simple.

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Re: 4l80e limp? No shift out of 2nd m1165

Post by RAS1 » Tue Mar 23, 2021 8:06 am

Thanks Ted! I am located in Rockford, IL. I have many extra 4l80e transmissions, I can always pull the 2 sensors from another and swap them. What do you think about swapping the TCM? What are the chances I may fry out a good new one?

thanks,
Dave

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Re: 4l80e limp? No shift out of 2nd m1165

Post by Ted Gates » Tue Mar 23, 2021 11:32 am

Slim unless wires are crossed or shorted. Only need to change the TOSS.

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Re: 4l80e limp? No shift out of 2nd m1165

Post by Retired War Horses » Sat Mar 27, 2021 8:50 am

If you have another TCM, install it....being you have no Trans lamp on, I would replace the Trans Relay, I had a truck do the same, no Trans lamp, no codes and stuck in limp mode.
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Re: 4l80e limp? No shift out of 2nd m1165

Post by RAS1 » Sat Mar 27, 2021 6:09 pm

The trans lamp lights at start, and blinks 12 when in test mode. But throws and shows no codes. I dont think the lamp or relay is bad since the light works. My main problem is why is it not shifting, and not throwing codes.

Dave

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Re: 4l80e limp? No shift out of 2nd m1165

Post by Action » Sat Mar 27, 2021 6:58 pm

RAS1 wrote:
Sat Mar 27, 2021 6:09 pm
The trans lamp lights at start, and blinks 12 when in test mode. But throws and shows no codes. I dont think the lamp or relay is bad since the light works. My main problem is why is it not shifting, and not throwing codes.

Dave
Have you switched any parts yet, as suggested by others above?

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Re: 4l80e limp? No shift out of 2nd m1165

Post by Retired War Horses » Sun Mar 28, 2021 7:16 am

RAS1 wrote:
Sat Mar 27, 2021 6:09 pm
The trans lamp lights at start, and blinks 12 when in test mode. But throws and shows no codes. I dont think the lamp or relay is bad since the light works. My main problem is why is it not shifting, and not throwing codes.

Dave
Sorry, can’t help you if you don’t want to replace parts as part of troubleshooting...
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Re: 4l80e limp? No shift out of 2nd m1165

Post by RAS1 » Mon Mar 29, 2021 10:02 pm

I'm out of town for 2 weeks. Will advise after.

Dave

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Re: 4l80e limp? No shift out of 2nd m1165

Post by RAS1 » Thu Apr 08, 2021 10:12 am

I changed out the TOSS, TISS, and the Transmission control module, no change. Still does not throw any codes, just flashes 12.

I am waiting on a miltope MSD V2 to try and pull some more information before I pull the trans.

The Transmission manual shows a different diagnostic tool, but I'm not sure where that one would hook into the system.

Has anyone used a Miltop MSD V2? with the Ste-Ice kit to test the transmission?

thanks,
dave

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Re: 4l80e limp? No shift out of 2nd m1165

Post by 86humv » Thu Apr 08, 2021 5:55 pm

A few people changed the relay thats close to the C/B behind battery box....sometimes they stick open or closed.
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Re: 4l80e limp? No shift out of 2nd m1165

Post by RAS1 » Thu Apr 08, 2021 9:05 pm

86humv wrote:
Thu Apr 08, 2021 5:55 pm
A few people changed the relay thats close to the C/B behind battery box....sometimes they stick open or closed.
Ty greg. I'll try it!
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Re: 4l80e limp? No shift out of 2nd m1165

Post by Retired War Horses » Sat Apr 10, 2021 8:23 am

    RAS1 wrote:
    Thu Apr 08, 2021 10:12 am
    I changed out the TOSS, TISS, and the Transmission control module, no change. Still does not throw any codes, just flashes 12.

    I am waiting on a miltope MSD V2 to try and pull some more information before I pull the trans.

    The Transmission manual shows a different diagnostic tool, but I'm not sure where that one would hook into the system.

    Has anyone used a Miltop MSD V2? with the Ste-Ice kit to test the transmission?

    thanks,
    dave
    It doesn’t work on the transmission via the ste/ice connector.....
    I have the test kit for the 4L80e, it’s not that great of a kit, when I get a head scratcher I go to my transmission shop, he is able to interface with the Trans and TCM and determine where the problem is.On several occasions my guy has found bad wires from the connection at the Trans to the TCM connector, simply running a tear wire resolved the issue...you won’t have codes
    If you have a bad wire
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    Re: 4l80e limp? No shift out of 2nd m1165

    Post by RAS1 » Sat Apr 10, 2021 8:24 pm

    Thanks much! I did a quick inspection of wiring and connectors, but I will get more detailed. I like the idea of a bad wire, as it won't throw the code. What connector do you use on the tcm to hook up to the tech tool? Does the tool need to be obd1? Or is obd2 ok?

    Thanks
    Dave


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