4L80E No shift from 2nd---SOLVED!

[cookeemann]

I'm out of ideas. Been chasing this one for about a week. Using the TM (Supp 7) and the internet. I have no test equip
Wasn't running when I got from GPnt. Bad IP-Replaced Injection Pump-runs fantastic. Drove, only up to 2nd gear. Shifted normal about three test drives after, but not now.
Pulling code 85 and 86 continuously (21 briefly but I moved the TPS and it went away-I know it needs to be adjusted).
Swapped / cleaned TIS and TOS-no change
Circuit Breaker behind battery box not tripped
Shifted xfer case through all ranges, operates perfect-no change
I cleaned/tightened all grounds
All connections tight
Both batteries new
Opened TCM box and controller looks brand new (but been in a sealed box I know)
Only thing I haven't checked is the brake switch that seems to be related
Any other help/recommendations would be greatly appreciated-first HMMWV-I'm a Deuce guy
--Cookeemann

 

[MrMikey4026]

This looks a pretty good trouble shooting manual.

https://gear-report.com/wp-content/uploads/2017/03/Supplement_7_4L80E-Transmission_Troubleshooting.pdf

GM manuals suggest input speed sensor faults.
You might check for corroded connectors.

 

[NDT]

Well since you ALREADY read supplement 7, you know you are in limp mode and you have “undefined ratio errors”. That means the computer is expecting a certain numerical ratio between the tiss and toss and it’s not seeing that. Why is the question. Could be several reasons such as smoked clutches. Time to open the pan and look for bad things.

 

[jnissen]

If you recently installed the motor did you backspace the converter properly? Can eat up a pump in a few miles if it’s too tight. Once the pump goes then pressures fall and clutches,etc fail short after.


Sent from my iPhone using Tapatalk

 

[Retiredwarhorses]

Your 85 is a bad or way out of adjustment TPS….check for proper voltage per the TM, replace the TPS.

 

[cookeemann]

Cleared the codes and drove it this am. Drove perfect. Stopped and drive again, stuck in 2nd and codes 85, 86 again. When I had the ip rebuilt, they replaced the housing and I think they just stuck the tps back on so it def needs adjusting.
Can you do it by just probing the wires with a meter? .5 at idle and 4.5 at 33% throttle with the meas block(which I don't have).

 

[frank8003]

Perhaps You answering Your own Qustitmons

 

[AAVP7]

The thickness of the gauge block is in the supplement 7 guide. 0.646 inches. If you want it super comfortable, there is a "throttle position sensor test cable" available, that provides three plugs to attach a multimeter to. However, you can also take those voltages with a needle probe stuck through the wire insulation.

Adjusting then is pretty straightforward. Just keep to the instructions in the guide. (page 65). Takes ten minutes.

 

[cookeemann]

Frank....perhaps.....anyway
Wire 350c was already skinned back so motorpool had already been in there before.
At idle, 350c shows 5.13v at full fwd, 5.15 full aft
355b 5.02 fwd, 4.99 aft
359h .01 both pos's
Will compare to TM when back from the field.
Looks like a bad TPS. Will post up final result to help others in the future.

 

[cookeemann]

Without the special lead, which wires do you check voltage from? The manual doesnt specify. Only says check between A and C, but not which wires that corresponds to. Any help is greatly appreciated! Cheers!

 

[AAVP7]

According to the troubleshooting guide:

A = 350 c = 5 Volts from TCM
B = 355 b = Sensor signal, between 0.5 and 4.5 volts
C = 359 h = Sensor ground

 

[cookeemann]

TALLY HO! Problem solved. Bad TPS.
Tried following the TM for adjustment and meas's, but no test lead, no test block and the procedure is poorly explained (21 years as a military mechanic qualifies me to make that determination I think).
So, per another forum, I adjusted the TPS to .5 volts meas'd between wire 355B and 359H with engine idling....problem solved. Hope this helps someone else in the future.
Recommend SS member AAVP7 for immediate field promotion for stellar assistance and service above and beyond the call..... Ooorahh!

 

[Retiredwarhorses]

TALLY HO! Problem solved. Bad TPS.
Tried following the TM for adjustment and meas's, but no test lead, no test block and the procedure is poorly explained (21 years as a military mechanic qualifies me to make that determination I think).
So, per another forum, I adjusted the TPS to .5 volts meas'd between wire 355B and 359H with engine idling....problem solved. Hope this helps someone else in the future.
Recommend SS member AAVP7 for immediate field promotion for stellar assistance and service above and beyond the call..... Ooorahh!

i told you in my post above it was a bad TPS…that’s what an 85 code …

 

[2mas-]

Hi, glad you found the problem. I also have the 85 and 86 code on my hmmwv. It happend after i changed the regulator on top of alternator. I guess it was bad or something. May it have damaged some of my sensors? TISS, TOSS or TPS. Can I measure on it to see if it is good or bad?

 

[AAVP7]

The "4L80 troubleshooting guide" that has been mentioned in this thread several times contains testing procedures for all sensors. That guide is a must-have for all 4L80 owners.

 

[cookeemann]

Retiredwarhorses, you sure did. You're the man. Thanks for putting me on the path.

 

[2mas-]

Do you unplug the wires when measuring the voltage at idling or go "through"/ skin the wire and measure with it plugged in?

 

[cookeemann]

Engine running, tps plugged in, trim back some of the wire insul to access the wire.

 

[jideshraj]

TALLY HO! Problem solved. Bad TPS.
Tried following the TM for adjustment and meas's, but no test lead, no test block and the procedure is poorly explained (21 years as a military mechanic qualifies me to make that determination I think).
So, per another forum, I adjusted the TPS to .5 volts meas'd between wire 355B and 359H with engine idling....problem solved. Hope this helps someone else in the future.
Recommend SS member AAVP7 for immediate field promotion for stellar assistance and service above and beyond the call..... Ooorahh!

HI, I am in a similar situation, truck not going past 2nd gear. I followed your steps, TPS Volt between A & C is 4.99 but B & C is 0. I have a couple of question,
1. Should I try to adjust existing TPS to 0.5 or should get a new unit and install that?
2. I was also splicing the wires, don't have the jumper tool or test block. Is that required to adjust TPS?