My 4L80E trouble codes

[taskunitbruiser]

I just ran diagnostics on my 4L80E

Four codes: 22, 85, 86, and 87

22: Throttle Position Low
85: Undefined Ratio
86: Low Ratio
87: High Ratio

HMMWV will slip going up hills and occasionally go into limp mode (gears 1 & 2). ATF is red but was low when I bought it, so I added Dexron VI. Tested level, per dipstick, idling in park (which reads lower than when off). Restarting vehicle gets it out of limp. Engine RPMs seems higher than should be. It does idle about 800 rpm, but often shifts in and likes to run around 2500. I think it should be more around ~2000rpm to stay closer to peak torque, am I correct?

Any guidance on those codes? I am not a transmission mechanic at all.

 

[Mogman]

In case you don't have this, if you think it is slipping the first step would be put a pressure gauge on it.

 

[Mogman]

It is normal for it to read high when off as the torque converter sometimes drains back into the pan.

 

[taskunitbruiser]

In case you don't have this, if you think it is slipping the first step would be put a pressure gauge on it.

Great manual. Looks like I need some specialty tools listed in the back. Is this something a transmission shop will have or does this need to go to a Humvee specialist?

 

[Mogman]

Great manual. Looks like I need some specialty tools listed in the back. Is this something a transmission shop will have or does this need to go to a Humvee specialist?

The mechanical side is the same as a civy transmission, they should be able to do basic troubleshooting such as putting a pressure gauge etc.
The electrical side will likely be foreign to them, all the basic controls are the same but there is no civy port (OBD) to read the TCM but that transmission was mostly diagnosed on the electrical side with the codes.
The reception you get depends on how curious they are to check it out.
You can do most of the electrical side with a multi meter.

 

[TNDRIVER]

Great manual. Looks like I need some specialty tools listed in the back. Is this something a transmission shop will have or does this need to go to a Humvee specialist?

4L80E, lots of them out there. Heavy duty trucks and vans and a few Motor homes. R & R your self that way the shop can't complain about it being in a HMMWV ....$$$$$ My 2 cents.

 

[Mogman]

It needs to be diagnosed, you could have sensor failures and slipping and going in and out of limp mode sometimes is caused buy a solenoid/valve failure, both relatively easy to repair.
It is best to have someone familiar with the 4L80 to do the pressure testing, they know what the pressures should look like as the transmission shifts up and down.

 

[Mogman]

It also would not be a bad idea to drop the pan and change the filter and look at the pan, if there is a significant pile of clutch material in the pan then it is pretty much game over, a small amount of "sludge" is normal, metallic flakes not so normal.
This is a BAD transmission!!

 

[Mogman]

If you live in a fairly large town/city check with the local hot rod guys, the 4L80 is a popular hot rod transmission and shops they deal with would be more likely to welcome you, many shops rather just deal with soccer moms etc.

 

[taskunitbruiser]

basic controls are the same but there is no civy port (OBD) to read the TCM but that transmission was mostly diagnosed on the electrical side with the codes.

My thought was give them the codes I already read and the manuals explaining everything since no OBDII port and such.

4L80E, lots of them out there.

I was counting on that in case it needs parts.

if there is a significant pile of clutch material in the pan then it is pretty much game over

Worse case scenario how much does a 4L80E cost? Another grand for installation labor?

 

[taskunitbruiser]

I also worry about the switch starting procedure, as in someone inexperienced using it. Sometimes my wait light comes on and stays and others it just flashes off immediately. I just count to 15-20 in this case and then try. I can see the current flowing to the glow-plugs on the voltimeter. A local shop guy said if he can't leave it in the shop or rack he can block it in (in case some thief cuts my cable wheel lock). No high speed chase possible. Hesitant to leave it somewhere.

I may leave a post-it notes in it about the starting haha.

 

[Mogman]

My thought was give them the codes I already read and the manuals explaining everything since no OBDII port and such.



I was counting on that in case it needs parts.




Worse case scenario how much does a 4L80E cost? Another grand for installation labor?

I don't think that TCM ever had a OBDII port, it had an OBD port which became known as the OBDI port when the OBDII port came out.
The OBD port on that TCM has a very limited amount of information, that is why it is mainly diagnosed using the codes and a pressure gauge.
The last transmission I had built about 3 years ago a 6L80 cost me $3000, off the dock and that included a custom modified torque converter, you can spend much more if you want to.

ONE thing do not go to a shop with the idea you need a new transmission or that is what you will get, vet the shop as well as you can, have no doubt that transmission shops are in the business of selling transmissions.

As stated before there are several reasons you could have these issues that are not fatal.

The wait light will not come on when the engine is warm/hot.

 

[AAVP7]

The very first error code you got, 22, points to the Throttle Position Sensor (TPS). Since this is a sensor external to the transmission, even a new transmission might still malfunction if this sensor was the culprit.

The TPS sits on the right side of the injection pump. It can be diagnosed pretty easily with a multimeter and the troubleshooting manual mentioned above. I´d first test and adjust the TPS if neccessary, and then see if this error code disappears.
The manual says you need a special testing cable, and a gauge brick. The dimension of the gauge brick is given in the TM however, so you can make one yourself. You don´t need the testing cable if you use multimeter tips with very small points that can poke through the cable´s isolation.

And then I´d go and see about the other codes. It could be as easy as just a loose or broken TPS.

 

[taskunitbruiser]

The very first error code you got, 22, points to the Throttle Position Sensor (TPS). Since this is a sensor external to the transmission, even a new transmission might still malfunction if this sensor was the culprit.

The TPS sits on the right side of the injection pump. It can be diagnosed pretty easily with a multimeter and the troubleshooting manual mentioned above. I´d first test and adjust the TPS if neccessary, and then see if this error code disappears.
The manual says you need a special testing cable, and a gauge brick. The dimension of the gauge brick is given in the TM however, so you can make one yourself. You don´t need the testing cable if you use multimeter tips with very small points that can poke through the cable´s isolation.

And then I´d go and see about the other codes. It could be as easy as just a loose or broken TPS.

Do you know if there is just one TPS or one near the injector pump and maybe a second on the transmission? I think just one.

I think all the codes stem from the same problem, so perhaps fixing whatever is wrong will cure them all? You clear the codes by disconnecting one of the battery cables for a few seconds right?

 

[Mogman]

Only one TPS, it would be the easiest to diagnose first, just go after them one at a time. however it is doubtful the TPS alone caused all the codes you are seeing but a defective or badly miss aligned TPS can cause "soft shifts" that could be mistaken for slipping.

The 85,86,87 codes are an indication of slipping or more sensor issues.

The TPS is about as simple as you can get, it is just a variable resistor with three leads, one is ground, one is the 5V reference and the other is the signal, the signal voltage should go up and down on the signal lead as the throttle is advanced and released.

The voltages you should see on the signal lead is listed in the troubleshooting guide.

IMHO it is far better to use an analog meter rather than a digital meter as you can easily see "bad" spots in the TPS as the analog meter will jump around as the throttle is moved rather than be a smooth "sweep" of the needle.

As stated above use a meter with sharp probes the pierce the insulation of the lead you are testing, the black meter probe goes to ground.

Of course be careful not to penetrate all the way through the wire shorting to something on the other side of the wire.

 

[TNDRIVER]

Do you know if there is just one TPS or one near the injector pump and maybe a second on the transmission? I think just one.

I think all the codes stem from the same problem, so perhaps fixing whatever is wrong will cure them all? You clear the codes by disconnecting one of the battery cables for a few seconds right?

I think I would pull the round plug on the driver side of the transmission and stick a qtip in it (you have to have a really small head to get an eyeball up to it) and see if it comes out "RED", that would be transmission fluid. It could account for all of your electrical gremlins but "probably" not the slipping. The plug can be cleaned with brake parts cleaner but the fluid will return . They are known to leak. Low cost and effort . My 2 cents.

 

[SmartDrug]

Re: Code 22

4L80e Code: 22 - Throttle Position Sensor low voltage

Took out the HMMWV for the 4th of July and all systems seemed fine, but it hung 1st gear until much higher in the RPMs (20+ mph 1-2 shift at mild throttle) and was a pretty rough shift when it finally did shift. Seemed to run through the gears, but all seemed late/rough, not stuck in 2nd/Limp...

www.steelsoldiers.com

 

[taskunitbruiser]

I have confirmed with the multimeter on the J1 that something is wrong with the TPS. Is it the wire or the sensor, not sure yet. Everything else on J1 looked to be in spec, although engine RPM was lower voltage than should have been.

Road testing it in manual mode with the J1 unplugged or trying to get it to upshift in T/C low range got me nowhere (more or less literally).

I just ordered a filter so will drop the pan soon to see if I find any metal flakes or signs of actual damage. I found the TPS location by following the throttle cable, but it isn't obvious to me how to take it out; I'm getting zero YouTube videos on Humvee TPS installation/removal. Looks like will need to start by pulling off the air intake which should be straightforward, but then do I need to disconnect the cables and take off the the throttle body to actually get the sensor off? I saw a tamper resistant Torx bolt head looking back at me on the throttle body. Why in hell would that be on there? I would have to get some new sockets if need to get that one off.

 

[Mogman]

I am a little confused, what does RPM have to do with the TPS?
So wire 350C, terminal A has 5v measured to ground?
and wire 350H terminal C measures near zero OHMs to ground?
And you have no voltage on wire 350B terminal B to ground?
All this is measured with the plug connected to the TPS.
Removing it is pretty straight forward, remove the two screws attaching it to the IP and it comes right off, do it with the throttle at idle.

 

[taskunitbruiser]

I am a little confused, what does RPM have to do with the TPS?
So wire 350C, terminal A has 5v measured to ground?
and wire 350H terminal C measures near zero OHMs to ground?
And you have no voltage on wire 350B terminal B to ground?
All this is measured with the plug connected to the TPS.
Removing it is pretty straight forward, remove the two screws attaching it to the IP and it comes right off, do it with the throttle at idle.

"Engine RPM" voltage test on the J1 spec is 0.3 V idle, 349A. I got 0.003 V. Actual RPM (the mechanical turning) is fine. 800 idle. It appears even if I manage to get the bolts off there isn't enough room to pull the sensor back to remove, see picture.