I got a intermittent trans problem that is getting me. First off My truck is a 95 3500 auto trans (4L80E I believe) Sometimes when I first start the truck in the AM it will be stuck in 2nd gear.I stop turn the key off and back on and it will clear but only for the first few times. After that it will be stuck until I hook up a scanner and clear the codes. (Paper clip and/or depressing brake and gas does not work for mine:( Neither does disconnecting batteries.:( )
Most of the time I clear the codes and it will run all day (Maybe 2) without any problem. When it does do it it is right off the bat, as soon as the key is turned on. I know this as I have borrowed a scanner and have it hooked up constantly.
The codes that I get are:
81 Shift Solenoid Circuit A
82 Shift Solenoid circuit B
83 TCC Quad driver Failure
I have replaced my ignition switch not too long ago and have dropped the trans pan and changed out (Or checked on bench as one solenoid was wrong from the dealer) all the shift solenoids.
This morning it stuck and would not clear. It came right back with the 82 Shift Solenoid circuit B only.(and a lot) Finally half way to work and constantly pressing "Clear codes" on the scanner it shifted and started working fine. One other thing, my ABS light has been on for a while before this. I have not checked the codes in the ABS sytem yet but will.(Have to exit and re-program VIN)
So where do I start? Bad ground? Speed sensors?

when it is not working check trans fuse and see if there is any power at it otherwise i would run a wire from the bat + to the pink wire at the trans connecter terminal "e" and go for a drive and see if problem is gone there are alot of problems with 95"S losing power to trans ign switch is one i usually run a relay to power the trans with problem units

http://www.atraonline.com/manuals/general/tetdv/tetdv-c3h.htm

this may or may not help. but worth a try

oops, this one is for your year vehicle.
http://www.atraonline.com/manuals/general/tetdv/tetdv-c3i.htm

mine does this occasionally when it starts to get colder. Never does it in the summer. ???

I did have a problem 2 years ago with it going in to 2nd gear and blowing the fuse for the trans. Turned out to be a pinched wiring harness located between the head and the firewall (pinch weld where the body sheetmetal come together). Located it by removing the harness connector at the trans and using a voltmeter. Found 7 or 8 wires grounded out. Traced the harness, found the pinch, used aircraft style barrel connectors to fix.

mine does this occasionally when it starts to get colder. Never does it in the summer. ???

I did have a problem 2 years ago with it going in to 2nd gear and blowing the fuse for the trans. Turned out to be a pinched wiring harness located between the head and the firewall (pinch weld where the body sheetmetal come together). Located it by removing the harness connector at the trans and using a voltmeter. Found 7 or 8 wires grounded out. Traced the harness, found the pinch, used aircraft style barrel connectors to fix.

Mine is getting worse as it is getting colder I noticed. I have checked power down at the trans and had power but still stuck in second? Clear codes and then would work? I think that I might still be losing power intermitently but after about 4 times the computer locks it up and it stays in second until clearing the codes.


when it is not working check trans fuse and see if there is any power at it otherwise i would run a wire from the bat + to the pink wire at the trans connecter terminal "e" and go for a drive and see if problem is gone there are alot of problems with 95"S losing power to trans ign switch is one i usually run a relay to power the trans with problem units.

Will have to try this. I have a new ignition switch but I am going to put it on relay's. (Heard of this trick)

A/T - 4L80_E 2nd Gear only After A Cold Start/DTC 87
Bulletin No.: 67-71-53B
Date: November 10, 2003
TECHNICAL
Subject:
No Upshift/2nd Gear Only After Cold Start-Intermittent DTC 87-High Ratio Error (Replace EPROM)
Models:
1994-1995 Chevrolet and GMC C, K, P Truck, G Van
1996 Chevrolet and GMC P Truck, G Van
Equipped with HYDRA-MATIC 4L80E Automatic Transmission (RPO MT1)
Supercede:
This bulletin is being revised to correct the electronic formatting. There have been no changes to the content of the bulletin. Please discard Corporate Bulletin Number 67-71-53A (Section 7 - Transmission).
Condition
Some owners may comment about no transmission upshift after a cold start. In conjunction, Diagnostic Trouble Code (DTC) 87 is setting intermittently causing the PCM (http://www.alldatadiy.com/alldata/AFI~V5685429~C21408~R0~OD~N/0/41746505/42420122/42420159/42420211/34853741/34857029/34857030/34857300) to command the default action of second gear only.
Cause
The commanded shift to third gear or fourth gear has taken longer than 2 seconds with a minimum 25% TP Sensor reading which has caused DTC 87 to set.
Correction
If normal diagnostics fail to lead to a resolution or the condition cannot be duplicated, replace the EPROM.
Service Information/Procedure
Check the PCM (http://www.alldatadiy.com/alldata/AFI~V5685429~C21408~R0~OD~N/0/41746505/42420122/42420159/42420211/34853741/34857029/34857030/34857300) for a current or history DTC 87. If DTC 87 is present, refer to the appropriate Service Manual for diagnosis of DTC 87. Refer to corporate bulletin # 577115 for additional information on diagnosing DTC 87. If the diagnosis fails to lead to a resolution and DTC 87 only sets after a cold start, replace the EPROM. Refer to the appropriate Service Manual for EPROM replacement. It is a good idea to verify the new EPROM I.D. with a scan tool against the application listed below.
The service EPROM raises the DTC 87 shift time parameter to 4 seconds and the code enabling temperature to 20°C (68°F).

A/T - 4L80_E 2nd Gear only After A Cold Start/DTC 87
Bulletin No.: 67-71-53B
Date: November 10, 2003
TECHNICAL
Subject:
No Upshift/2nd Gear Only After Cold Start-Intermittent DTC 87-High Ratio Error (Replace EPROM)
Models:
1994-1995 Chevrolet and GMC C, K, P Truck, G Van
1996 Chevrolet and GMC P Truck, G Van
Equipped with HYDRA-MATIC 4L80E Automatic Transmission (RPO MT1)
Supercede:
This bulletin is being revised to correct the electronic formatting. There have been no changes to the content of the bulletin. Please discard Corporate Bulletin Number 67-71-53A (Section 7 - Transmission).
Condition
Some owners may comment about no transmission upshift after a cold start. In conjunction, Diagnostic Trouble Code (DTC) 87 is setting intermittently causing the PCM (http://www.alldatadiy.com/alldata/AFI~V5685429~C21408~R0~OD~N/0/41746505/42420122/42420159/42420211/34853741/34857029/34857030/34857300) to command the default action of second gear only.
Cause
The commanded shift to third gear or fourth gear has taken longer than 2 seconds with a minimum 25% TP Sensor reading which has caused DTC 87 to set.
Correction
If normal diagnostics fail to lead to a resolution or the condition cannot be duplicated, replace the EPROM.
Service Information/Procedure
Check the PCM (http://www.alldatadiy.com/alldata/AFI~V5685429~C21408~R0~OD~N/0/41746505/42420122/42420159/42420211/34853741/34857029/34857030/34857300) for a current or history DTC 87. If DTC 87 is present, refer to the appropriate Service Manual for diagnosis of DTC 87. Refer to corporate bulletin # 577115 for additional information on diagnosing DTC 87. If the diagnosis fails to lead to a resolution and DTC 87 only sets after a cold start, replace the EPROM. Refer to the appropriate Service Manual for EPROM replacement. It is a good idea to verify the new EPROM I.D. with a scan tool against the application listed below.
The service EPROM raises the DTC 87 shift time parameter to 4 seconds and the code enabling temperature to 20°C (68°F).

I have not had a DTC 87 yet in history or otherwise so I don't think it is this. (I hope) I'm still thinking the loose wire theory. If it is EPROM can I use one out of a 97?. I know it is OBDII instead of OBDI but are the EPROM's the same? The reason why I ask is that I have a 97 available to use for any testing purposes.

When mine did that exact same thing it went away after I replaced both the input and output speed sensors. Especially I would say the output sensor in your situation, which would explain the ABS light that you got. The rear ABS sensor is also the trans output speed sensor. I would do them both. The input is on the drivers side just behind the bell housing. The output is different on 2wd and 4wd the 4wd one being on the transfer case and 2wd near the tailcone. At about 30 bucks a piece and 15 min to change both its worth a shot.

When mine did that exact same thing it went away after I replaced both the input and output speed sensors. Especially I would say the output sensor in your situation, which would explain the ABS light that you got. The rear ABS sensor is also the trans output speed sensor. I would do them both. The input is on the drivers side just behind the bell housing. The output is different on 2wd and 4wd the 4wd one being on the transfer case and 2wd near the tailcone. At about 30 bucks a piece and 15 min to change both its worth a shot.

Thanks, Will change if they are that cheap!( At least then I know I won't have a problem with them)

PDJ

Did replacing the sensors fix the problem? My wife's burb is having the same problem and I am about 90% sure it is probably one of teh two sensors.

is this a item the dealer will fix at gm's expence? ie recall item

Factory eprom for you truck is cheap. #16244781 is for a 95 2500 sub. Can be had for about 40 bucks. Very easy to change. May be worth a try.

if i recall the trans has a computer of its own which unit i change for the transmission and if trans computer where is it at?

I pulled the wiring harness out by accident and now and I'm getting DTC 81 shift solenoid B as a hardcode, I have probed the wires of the tranny connector and internally for 12v and grounds and I am wondering if I could have a break in the speed senor wire as well that is kepping this code active.

A friends 98 C3500 did this and after changing wiring harness and shift solenoid the dealer found a bad computer. Nothing bout 400.00 won't fix and did. Runs great now

Actually, now it's three codes. DTC 81, 82, 83, shift a , shift b and TCC solenoid. All have 12v and wires are good to ECM. Changed ECM, but ued old prom chip, nothing changed.

The above pn for a '95 prom cleared the tranny codes but It cost $70 at the local stealer.

Sorry for the delay.Been away for a while. I narrowed my problem to the connector at the trans. (Loose/dirty connections) I fixed the problem by taking a needle and pushing the sides of female pin connector down at the trans (Truck side) and spraying a contact cleaner in the plug. I had power at the solenoids before I did this but the PCM checks a feedback thru the ground on each solenoid. I changed the eeprom in the PCM as It was not to expensive and it was a upgrade although it did nothing for the trnas issue.Anyway it's fixed now and no need to buy a new connector or harness.(Yet)

One other thing. A couple times I had to clear my codes after testing to get it to work. (Stuck in second---fix wiring----still stuck--clear codes---works fine)
I think I may dam near be a expert on this now but definitely not by choice!