4l80e problem symptoms

[erasedhammer]

4l80 starts out in 1st gear. Shifts into second, then doesn't shift up any further.
While on the road, I can shift from D into 2 and it will downshift ONLY when going above 30 MPH.

When hooked up to a civi computer the transmission will manually shift through all gears. Solenoids are fine.

This problem is not listed in the troubleshooting manual, anyone have a diagnoses?



Also when I short pins A and E on the J2 connector on the TCM then turn ignition to run, the warning lamp doesn't do anything. No flashing.
There is power in the tranny and the computer. Haven't checked the lamp, but I got it new from Kascar, would be a shame if they sold me a dud. Harness is brand new so I don't expect any problems there.

 

[Wire Fox]

Damaged TCM or EPROM chip? Does anybody know of any diagnostic tests for the TCM itself to ensure its internal logic isn't borked? It's literally the same as any old 4L80E GM TCM, so a diag. must exist somewhere.

 

[erasedhammer]

Damaged TCM or EPROM chip? Does anybody know of any diagnostic tests for the TCM itself to ensure its internal logic isn't borked? It's literally the same as any old 4L80E GM TCM, so a diag. must exist somewhere.

I just found out the tcm was for a m1113/4, which means the shift points could just be extremely high. Which only makes the problem unsolvable because I can't find any chips for the lower weighted vehicles and i dont know how to reprogram those chips.

 

[someoldmoose]

Ah, new thread for the same discussion. My suggestion is to have someone with an appropriate scan tool plug in and analyze what is going on. Sounds like it's in "limp" mode. Know anyone that works at a Chevy truck store / service center ? Buy them some refreshment and have them give her a look-see. I DO NOT recommend just throwing parts at it. There are aftermarket scanners available but they are very salty ($ 1500 +). Electronic engines are why I got out of the garage. Electronic transmissions made me wanna leave the planet.

I was typing my reply when your latest posted. Find the right TCM or swap in a 700R4. Same trans without electronic controls.

No problem is ever "unsolvable".

 

[erasedhammer]

Ah, new thread for the same discussion. My suggestion is to have someone with an appropriate scan tool plug in and analyze what is going on. Sounds like it's in "limp" mode. Know anyone that works at a Chevy truck store / service center ? Buy them some refreshment and have them give her a look-see. I DO NOT recommend just throwing parts at it. There are aftermarket scanners available but they are very salty ($ 1500 +). Electronic engines are why I got out of the garage. Electronic transmissions made me wanna leave the planet.

I was typing my reply when your latest posted. Find the right TCM or swap in a 700R4. Same trans without electronic controls.

No problem is ever "unsolvable".

The shop I was having look at the problem said all of their scanners wouldn't fit, and since my trans warn lamp doesn't work I have to do some good hard thinking and hopefully come up with a solution. Or get the EPROM reprogrammed... and fix my trans warn lamp...

Were you able to get the vehicle my EPROM was on?

 

[someoldmoose]

Put it in the other thread. My source said it's for a '94 6.2 L diesel. I am guessing you bought this vehicle like this ? Sounds like someone was monkeying around with it.

My . for what you'll spend on diagnosis and locating the replacement parts you can most likely buy and install a very well built 700R4. No, I don't sell them so I am not gonna make a dime off of this. Just have had both kinds and when the 4L60 in my Blazer goes it's getting a 700R4. I understand why electronics have come to be, doesn't mean I have to like them.

Sorry, just an old caveman. Like stuff I can fix with a rock and a long, strong stick.

 

[Wire Fox]

I just found out the tcm was for a m1113/4, which means the shift points could just be extremely high. Which only makes the problem unsolvable because I can't find any chips for the lower weighted vehicles and i dont know how to reprogram those chips.

Have a correction to post here... we're looking on non-programmable PROM chips for this TCM. As an FYI, later model years will use a different TCM that's programmable in itself, no PROM, EPROM, or other user-removable chip used.

Some other details... Stumbled into this thread, which has a good diagnostic idea: http://www.doityourself.com/forum/p...68547-gm-4l80e-transmission-not-shifting.html

Some Marine in LeJune was having the exact same struggle. Two diagnostic ideas tossed in were as follows:

1) Swap the TISS and TOSS sensors themselves. That way, you don't have to buy any new since they're the same, but if you have any change in behavior from this swap, you know at least one of the sensors is bad OR you have a bad connection to a sensor.
2) Ensure your system voltages are correct. Verify your alternator output is correct, and make sure that your TCM is being fed a proper 12-14V for its operation. If it's getting anything wildly outside of that, our issue is that the TCM doesn't have the right operating voltage and can't process properly.

 

[erasedhammer]

Have a correction to post here... we're looking on non-programmable PROM chips for this TCM. As an FYI, later model years will use a different TCM that's programmable in itself, no PROM, EPROM, or other user-removable chip used.

Some other details... Stumbled into this thread, which has a good diagnostic idea: http://www.doityourself.com/forum/p...68547-gm-4l80e-transmission-not-shifting.html

Some Marine in LeJune was having the exact same struggle. Two diagnostic ideas tossed in were as follows:

1) Swap the TISS and TOSS sensors themselves. That way, you don't have to buy any new since they're the same, but if you have any change in behavior from this swap, you know at least one of the sensors is bad OR you have a bad connection to a sensor.
2) Ensure your system voltages are correct. Verify your alternator output is correct, and make sure that your TCM is being fed a proper 12-14V for its operation. If it's getting anything wildly outside of that, our issue is that the TCM doesn't have the right operating voltage and can't process properly.

I don't know exactly what year the computer is, but it came with a 2003 4l80e if that makes any difference. The chip is removable. So for a 2003 tranny I'd have to have 2001 or newer chip right? Were those EPROM
I think I'll switch the TISS and TOSS and see what happens... I'm up for trying anything at this point to find out whats wrong.
I do know that 12v is at the transmission connector itself, so thats all good.

 

[Wire Fox]

I don't know exactly what year the computer is, but it came with a 2003 4l80e if that makes any difference. The chip is removable. So for a 2003 tranny I'd have to have 2001 or newer chip right? Were those EPROM
I think I'll switch the TISS and TOSS and see what happens... I'm up for trying anything at this point to find out whats wrong.
I do know that 12v is at the transmission connector itself, so thats all good.

Every unit with the removable chip is going to be just a PROM chip. We were all mistaken in calling it an EPROM chip earlier. Really, for this discussion, it's just semantics...I just don't like carrying on saying the wrong thing once I realize I was saying the wrong thing. The newer style of unit will be build differently and simply won't have a removable chip...there will just be some kind of programming tool to reflash the entire TCM to the desired shift pattern necessary for the vehicle. I don't know what year this switch occurred, but I'm sure one of the veteran restorers on here would know. I'm going to review the two 4L80E guides I have and see if I can spot anything that we may have missed so you have some more diagnostic procedures to try...

 

[erasedhammer]

Every unit with the removable chip is going to be just a PROM chip. We were all mistaken in calling it an EPROM chip earlier. Really, for this discussion, it's just semantics...I just don't like carrying on saying the wrong thing once I realize I was saying the wrong thing. The newer style of unit will be build differently and simply won't have a removable chip...there will just be some kind of programming tool to reflash the entire TCM to the desired shift pattern necessary for the vehicle. I don't know what year this switch occurred, but I'm sure one of the veteran restorers on here would know. I'm going to review the two 4L80E guides I have and see if I can spot anything that we may have missed so you have some more diagnostic procedures to try...

I've heard the m1114 chips when put in a m998 or similar vehicle causes the shift points to be ridiculously high, like red line for 3rd gear. And if it's not programmable, I'll have to find a chip from I guess a h1 or some 10k humvee? m1123, m1097a2, ect.?

 

[someoldmoose]

The voltage issue is absolutely vital. No computer will work without the correct input voltage and solid grounds. The speed sensors might cause problems but like it said in the DIY.com post. A veteran trans guy had no good first answer and suggested trying the sensor swap. Won't hurt anything to try but a few key items here have put my spidey senses on tingle.

IF the TCM was somehow given a steady diet of 24v (somehow), it's toast.
IF the wrong prom (and on you mentioning it, I'm not sure if this year even has a removable chip in the TCM - just don't remember) was put in somehow I can only imagine the mayhem it would cause.
IF you have followed the troubleshooting charts / trees for the TM and the perhaps even gone above and beyond with the GM factory trouble trees and haven't found an answer then I have nothing more to add. Sorry.

 

[erasedhammer]

The voltage issue is absolutely vital. No computer will work without the correct input voltage and solid grounds. The speed sensors might cause problems but like it said in the DIY.com post. A veteran trans guy had no good first answer and suggested trying the sensor swap. Won't hurt anything to try but a few key items here have put my spidey senses on tingle.

IF the TCM was somehow given a steady diet of 24v (somehow), it's toast.
IF the wrong prom (and on you mentioning it, I'm not sure if this year even has a removable chip in the TCM - just don't remember) was put in somehow I can only imagine the mayhem it would cause.
IF you have followed the troubleshooting charts / trees for the TM and the perhaps even gone above and beyond with the GM factory trouble trees and haven't found an answer then I have nothing more to add. Sorry.

Well I got a lot of good options to try, thanks for all the assistance.

 

[Wire Fox]

Well I got a lot of good options to try, thanks for all the assistance.

Yeah, I was just reading through the Supplement 7 4L80E Transmission Troubleshooting Guide. It has lots of pretty color pictures of the equipment in the HMMWV, lots of pretty charts with error codes, and great diagnostic flow charts and instructions on how to read the codes without a scan tool. There's flow charts the even help you troubleshoot and correct the diagnostic mode, in case it's not working correctly. (I think you said that the TRANS light wasn't illuminating at some point?) If you follow this guide to the last "T" and get everything operational, then you should be able to get solid diagnostic right from the TCM itself and we can call this issue troubleshot. We should, at a minimum, be able to blink out a Code 12 for being in diagnostic mode. If we can't get that, then we know we've got a major issue with wiring, the lamp, or the TCM itself...

 

[erasedhammer]

Yeah, I was just reading through the Supplement 7 4L80E Transmission Troubleshooting Guide. It has lots of pretty color pictures of the equipment in the HMMWV, lots of pretty charts with error codes, and great diagnostic flow charts and instructions on how to read the codes without a scan tool. There's flow charts the even help you troubleshoot and correct the diagnostic mode, in case it's not working correctly. (I think you said that the TRANS light wasn't illuminating at some point?) If you follow this guide to the last "T" and get everything operational, then you should be able to get solid diagnostic right from the TCM itself and we can call this issue troubleshot. We should, at a minimum, be able to blink out a Code 12 for being in diagnostic mode. If we can't get that, then we know we've got a major issue with wiring, the lamp, or the TCM itself...

Could you attach that document up? I don't believe I have that one. Sounds pretty useful.

If I go through the various checks for the system and find that its not the wiring and not the lamp and the TCM is just fried, I'll have to just get another box...
Which brings me to the question, I know that I should match the box to the transmission, but what happens if I hook up a 1996 TCM to my 2003 4l80?

 

[erasedhammer]

Yeah, I was just reading through the Supplement 7 4L80E Transmission Troubleshooting Guide. It has lots of pretty color pictures of the equipment in the HMMWV, lots of pretty charts with error codes, and great diagnostic flow charts and instructions on how to read the codes without a scan tool. There's flow charts the even help you troubleshoot and correct the diagnostic mode, in case it's not working correctly. (I think you said that the TRANS light wasn't illuminating at some point?) If you follow this guide to the last "T" and get everything operational, then you should be able to get solid diagnostic right from the TCM itself and we can call this issue troubleshot. We should, at a minimum, be able to blink out a Code 12 for being in diagnostic mode. If we can't get that, then we know we've got a major issue with wiring, the lamp, or the TCM itself...

Also I just read through one of many 4l80 info documents and it talked about the EPROM and PROM chips. Both are reprogrammable, but the EPROM, the 2001+ 2nd generation TCM is a non removable chip that is probably just easier to program. But both are programmable, probably a SOB to find a tool that can.

 

[someoldmoose]

Aha ! You have an '03 trans? (did I miss that earlier) The TCM absolutely should be the same year as the trans. Engineers just love to change circuits between model years. Keeps techs on their toes. Imagine a '96 TCM that speaks French trying to communicate with '03 sensors and wiring that speak Greek. No bueno, and you might just have discovered your problem. Wire fox is also right on. Quick ECM test back in the day was to jumper the data link to see if she'd blink hello (code 12), if not we sent her for a core.

Basics, basics, basics

 

[erasedhammer]

Aha ! You have an '03 trans? (did I miss that earlier) The TCM absolutely should be the same year as the trans. Engineers just love to change circuits between model years. Keeps techs on their toes. Imagine a '96 TCM that speaks French trying to communicate with '03 sensors and wiring that speak Greek. No bueno, and you might just have discovered your problem. Wire fox is also right on. Quick ECM test back in the day was to jumper the data link to see if she'd blink hello (code 12), if not we sent her for a core.

Basics, basics, basics

Well I'd like to say I have the correct matching TCM, since it came with the transmission, but you never know with these ebay sellers. I have another box that I'd liked checked up on. I'll have the chip number tomorrow.
As for the box, If anyone knows where to get new computers for specific transmission years I'd like to know. Can't find any chips anywhere.

 

[erasedhammer]

Yeah, I was just reading through the Supplement 7 4L80E Transmission Troubleshooting Guide. It has lots of pretty color pictures of the equipment in the HMMWV, lots of pretty charts with error codes, and great diagnostic flow charts and instructions on how to read the codes without a scan tool. There's flow charts the even help you troubleshoot and correct the diagnostic mode, in case it's not working correctly. (I think you said that the TRANS light wasn't illuminating at some point?) If you follow this guide to the last "T" and get everything operational, then you should be able to get solid diagnostic right from the TCM itself and we can call this issue troubleshot. We should, at a minimum, be able to blink out a Code 12 for being in diagnostic mode. If we can't get that, then we know we've got a major issue with wiring, the lamp, or the TCM itself...

Also, what should be the proper voltage and wave pattern for the ESS? Just took a quick look through the 4l80 manuals I have and it doesn't mention that

 

[Wire Fox]

Also I just read through one of many 4l80 info documents and it talked about the EPROM and PROM chips. Both are reprogrammable, but the EPROM, the 2001+ 2nd generation TCM is a non removable chip that is probably just easier to program. But both are programmable, probably a SOB to find a tool that can.

Not sure where I found this...I think it might have been a random post on here sharing it a month or so ago... Either way, knowledge is best shared, so here you go!

This thing's pretty much the Alpha and Omega of 4L80E electrical troubleshooting guides, because it pretty much covers everything... I think my only complaint on it is its organization. Just as soon as you think its skipped something important, it tells you it 2-3 sections later. Oh, and I think some of the high-level diagnostics on the mechanical issues have some pretty extreme solutions...it likes to say "Replace transmission" a few too many times, especially for things that have an obvious solution. I think this guide assumes that you're not authorized to actually open the transmission and access anything beyond the valve body.

As for your ESS, I'm not sure exactly how it's supposed to read out while in operation. It's going to be another 12V-operated sensor, since it's directly connected to the TCM. I may have missed it while scanning through. It did mention that to test the sensor itself while disconnected, you can do a resistance check on pins 1 & 2 to make sure it's between 100-200 Ohm.

 

[someoldmoose]

erasedhammer, wave sizes, shapes, and voltages are around step 372. You haven't confirmed step 1. To answer as asked though, the voltage and frequency will vary with rotational speed. The shape will be roughly a square wave _]-[_]-[_ (the dashes belong at the top of the brackets, don't have a fancy keyboard right now).

Wire fox, thank you for putting that up. I had Chevy's version but can't find it. "Hammer", if the answer isn't in that book, it doesn't exist. I agree it gets confusing at times but follow through. One step at a time. Remember though, a few basic assumptions are involved. It is written for parts that belong together. THAT above all else needs to be confirmed first.