1097A2 help needed

[Maverickjcw]

Took my 1097 off-roading in October 2021 and started having problems with it starting strong and would gradually lose power on the way home (80 mile trip). Checked the speed sensors, not the problem. Drained the 4L80E transmission, replaced both the the 1-2 and 2-3 shift modules, filter and put in new fluid, and had some relief but still having problem. Took it to the shop that does the work on the 1097 I cannot. That shop ruled out both the transmission and the TCM. The shop did come back and say the sensor in the attached pictures was disconnected and corroded and probably the cause of the slow power loss. The shop found the sensor was connected to the main wire harness and located where the transmission and transfer come together. The sensor was not internal but instead tied up with wire ties inside the rubber sleeve also in the attached pictures. Looking for some help in finding out what this is. I am thinking transfer case speed sensor. Neither I nor the shop can find what this sensor is in the TMs and there is nothing looks exactly like it through the normal suppliers like MAC Motors, Midwest Military, Eastern Military Surplus or SECO. Any help would be greatly appreciated.

 

[TOBASH]

Those look like Packard connectors and not sensors unless I’m missing something in the picture

 

[papakb]

Is your transfer case lock light working? There are 2 Packard connectors in that area that connect it to the main harness.

 

[Mogman]

I am a little curious how you zeroed in on the transmission? POWER is the engines responsibility, TRANSFER of power is the transmissions responsibility.
I cannot think of a situation that would cause the transmission to consume the power from the engine unless something horrific is going on inside, The transmission can slip, it can also be in limp mode and not shifting correctly, but a loss of power suggests the engine has issues.

 

[TNDRIVER]

Took my 1097 off-roading in October 2021 and started having problems with it starting strong and would gradually lose power on the way home (80 mile trip). Checked the speed sensors, not the problem. Drained the 4L80E transmission, replaced both the the 1-2 and 2-3 shift modules, filter and put in new fluid, and had some relief but still having problem. Took it to the shop that does the work on the 1097 I cannot. That shop ruled out both the transmission and the TCM. The shop did come back and say the sensor in the attached pictures was disconnected and corroded and probably the cause of the slow power loss. The shop found the sensor was connected to the main wire harness and located where the transmission and transfer come together. The sensor was not internal but instead tied up with wire ties inside the rubber sleeve also in the attached pictures. Looking for some help in finding out what this is. I am thinking transfer case speed sensor. Neither I nor the shop can find what this sensor is in the TMs and there is nothing looks exactly like it through the normal suppliers like MAC Motors, Midwest Military, Eastern Military Surplus or SECO. Any help would be greatly appreciated.

Sounds like my notorious pet peeve, Fuel delivery or lack thereof. My 2 cents for whats its worth.

 

[Mogman]

Sounds like my notorious pet peeve, Fuel delivery or lack thereof. My 2 cents for whats its worth.

That would be the most common cause of a power loss, I am sure you have cleaned the fuel tank and changed all the filters as needs to be done on any vehicle that has sat for years without use.

 

[Maverickjcw]

Took my 1097 off-roading in October 2021 and started having problems with it starting strong and would gradually lose power on the way home (80 mile trip). Checked the speed sensors, not the problem. Drained the 4L80E transmission, replaced both the the 1-2 and 2-3 shift modules, filter and put in new fluid, and had some relief but still having problem. Took it to the shop that does the work on the 1097 I cannot. That shop ruled out both the transmission and the TCM. The shop did come back and say the sensor in the attached pictures was disconnected and corroded and probably the cause of the slow power loss. The shop found the sensor was connected to the main wire harness and located where the transmission and transfer come together. The sensor was not internal but instead tied up with wire ties inside the rubber sleeve also in the attached pictures. Looking for some help in finding out what this is. I am thinking transfer case speed sensor. Neither I nor the shop can find what this sensor is in the TMs and there is nothing looks exactly like it through the normal suppliers like MAC Motors, Midwest Military, Eastern Military Surplus or SECO. Any help would be greatly appreciated.

Those look like Packard connectors and not sensors unless I’m missing something in the picture

That’s what I thought when talking to BV the mechanic. But when I got to his shop he showed me and slid the piece in my fingers out of the rubber sleeve. That piece in my fingers(in the picture) is solid with a flat end and a connection point on the other end. That connection I can see corroded wire in side of it

 

[Maverickjcw]

That would be the most common cause of a power loss, I am sure you have cleaned the fuel tank and changed all the filters as needs to be done on any vehicle that has sat for years without use.

All filters were changed in august 2021

 

[Maverickjcw]

All filters were changed in august 2021

Also the power list is vey much like going in to limp mode where I can reach 25-35 mph and that is it

 

[Mogman]

That’s what I thought when talking to BV the mechanic. But when I got to his shop he showed me and slid the piece in my fingers out of the rubber sleeve. That piece in my fingers(in the picture) is solid with a flat end and a connection point on the other end. That connection I can see corroded wire in side of it

That could be a "cap" used to seal off a female Packard connector that is not being used

 

[Mogman]

Also the power list is vey much like going in to limp mode where I can reach 25-35 mph and that is it

OK so at 25 MPH are you really revved up like the transmission will not shift or is it just running out of power? the more you describe it sounds more like fuel starvation, the engine is mechanical it has no "limp" mode to restrict power. Basically if it is running the IP and your foot are all that limits the power.

 

[Coug]

Easy way to check for fuel starvation of it's in the tank, lines, or lift pump.

Start the truck, run it, and open the little fuel drain valve in the front driver's wheel well.

If fuel streams out, you know the system is good up to that point.

If no fuel comes out, then the truck sounds funny and dies, your fuel system has issues.


When my lift pump went out I could still drive, but truck was severely lacking in the amount of power it had.

As others have said, if it's a speed issue and not shifting, then it's the transmission. Anything else is engine power loss.

 

[Maverickjcw]

Sounds like my notorious pet peeve, Fuel delivery or lack thereof. My 2 cents for whats its worth.

Good suggestion. I will go back with a fuel delivery issue in mind.

 

[Maverickjcw]

OK so at 25 MPH are you really revved up like the transmission will not shift or is it just running out of power? the more you describe it sounds more like fuel starvation, the engine is mechanical it has no "limp" mode to restrict power. Basically if it is running the IP and your foot are all that limits the power.

shifting 1-2, 2-3 no problems. At 25mph I can have the accelerator all the way on the floor and i won't be able to get any faster unless I remove my foot all the way from the accelerator then it will shift in to overdrive and get to 35mph.

 

[Maverickjcw]

shifting 1-2, 2-3 no problems. At 25mph I can have the accelerator all the way on the floor and i won't be able to get any faster unless I remove my foot all the way from the accelerator then it will shift in to overdrive and get to 35mph.

but currently no faster than 35mph. Before having this problem HMMWV would get to 60mph.

 

[Retiredwarhorses]

That piece is a large diode of sorts on later model truck, it’s held on via a p-clamp on the TOSS bracket.
It’s not needed, never could get a an answer of what its purpose is.
Your issue is most likely fuel relate, have you:
1. check your fuel pump by opening the water separator?
2.changed fuel filter and inspected for algae?
3. checked fuel tank for algae?
4. removed fuel line feed and return check valves?

 

[Mogman]

shifting 1-2, 2-3 no problems. At 25mph I can have the accelerator all the way on the floor and i won't be able to get any faster unless I remove my foot all the way from the accelerator then it will shift in to overdrive and get to 35mph.

Yep, sounds like fuel for sure as Coug said it could be a fuel pump, or a restricted fuel system.
If you are getting good pressure to the fuel filter water tap then it could be a plugged return check valve in the IP, that will also cause a loss of power but you should confirm good flow to the IP before worrying about the return.

 

[Action]

Later models have sveral diodes at dead end wires. There will be a metal tag on that wire what is the number?

 

[Action]

Later models have sveral diodes at dead end wires. There will be a metal tag on that wire what is the number?

589f and 290f
.
.

 

[86humv]

That is a noise suppression capacitor # 12469147....here's one still mounted on trans sensor bracket...I have spares.