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4L80E no overdrive

zielinski.family

zielinski.family

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Messages
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Location
Richmond, MO
I have scoured this whole section for help. My transmission is giving me problems. It runs fine when cold except for a hard 1-2 shift but when it warms up I loose over drive. I know check grounds but what else should I investigate?

It is on a 1993 gmc 2500 mechanical pump
 
Ok, I pulled codes this morning. On firsts attempt, (having never done it and not knowing what to expect) I got a code 73 and code 83. Are these two related? I was going to retrieve them again and see if I missed one on account I didn't figure out the flash sequence till the end. It cycled back and did it two times and I counted the two codes only. Does this mean the tranny is needing rebuilt? Or can one just replace the bad solenoid and torque converter? And if I was replacing the one solenoid, would it be wise to change all the others? What would be the best torque converter for this tranny?
 
On firsts attempt, (having never done it and not knowing what to expect) I got a code 73 and code 83. Are these two related? I was going to retrieve them again and see if I missed one on account I didn't figure out the flash sequence till the end. It cycled back and did it two times and I counted the two codes only. Does this mean the tranny is needing rebuilt? Or can one just replace the bad solenoid and torque converter? And if I was replacing the one solenoid, would it be wise to change all the others? What would be the best torque converter for this tranny?
Click to expand...

I know it's been a long holiday weekend, but could some one with experience chime in on this post, please? I really need my truck back on the road. I don't trust local shops, not that they don't know transmissions, but that they don't know 6.5's. ;)

I'm not sure if this problem in tranny specific or if it includes the TPS?
Help!!!!!!!!!!!!!!
 
DTC 73 - Pressure Control Solenoid Circuit (Current Error)
DTC 83 - Torque Converter Clutch

These look electrical from the combined codes.
Check grounds.
Check the main transmission plug for trans oil. Clean the plug with electrical cleaner.
Check the speed input and output wires. There are 2 plugs with 2 wires each. The insulation likes to flake off the wires and short.

How is the fluid level and condition?
Slipping or other issues would give a ratio error as I recall.
 
Hello,
I was the diagnostic person for 4L80-E Trans at the Proving Grounds. The 1st item I would do is: (After insuring the DTC's from the TCM)
Replace the internal wiring harness and correctly splice in the external mating harness. (The pass-through connector had a host of connection problem along with leaking ATF.)
DTC 73 - Pressure Control Solenoid Circuit (Current Error)
Diag action would turn off the FM for the key cycle and possible turn it off IF 10 key cycles were logged with this DTC in a row.) HARD Shifts
DTC 83 - Torque Converter Clutch
Diag Action could be INHIBIT 4TH GEAR

Another item back then was the shift solenoids. The B sol had the Highest failures. (It stayed in the OFF mode the longest and the BALL ran around it's enclosed cage and BEAT the ball seat EGG Shaped. Hence the 4th Gr working with COLD ATF and not HOT. Elongagted seat leaking atf allowing the shift valve to slide back.
As far as I know the TCC sol is not a major problem.
With your Truck you need to check and keep in mind the IGN SWITCH can fail giving you fits with Trans Electrical codes as well.

I put a couple of additional magnets in the pan. In the 93 4L80-E (and 91-92) it used a Silver Force Motor or the BOSCH. DO NOT replace it with the Black Holley or the Black Borg-Warner. Pressure rise could break parts. Also: The FM has a "cleaning Cycle" coded into the BOX or software that strokes the FM. That's why the Aux Valvebody had the LARGE spring with the small valve in it.
It is BEST to keep these parts together: The FM, Vavlebody, Spacer plate and Aux Valvebody and TCM/PROM. This goes for 1991-1993 and 1994-2004TCM controllers.
 
Welcome, billyg!
The TCC solenoid would wear out the valve body, leak, and trip the TCC code if the fluid wasn't kept clean by changing it often.

My favorite way to kill a 4L80E is to scatter the OD by ruining a bearing or sprag that goes through the gear set. That gear set gets a lot of wear anyway. Was a really exciting noisy lack of a 4th gear shift...

Other things I have done is burn up the TCC clutch and burn off the 'small' manual 2nd gear compression braking clutch.

Tough transmission otherwise. Couple of lube flow improvements can be made during an overhaul, but, not much else needed.
 
Update: so after much consideration I decided to go ahead and drop the pan and replace the filter, solenoids A & B, Tcc solenoid and pressure solenoid. I figured since it was electrical in nature that would solve the issue. The fluid was brown in color but there wasn't any shavings in pan, there was metal dust but that is to be expected. As I began to remove solenoids I ran into problems real fast. The screws that hold the solenoids in stripped out. So I had to drop the valve body. When the springs and ball-bearings went everywhere I bought fainted. I had to drill the screw heads off so I could replace solenoids. Replaced with grade 8 bolts, so if there is a next time it will be easier to deal with.

When I got to the pressure solenoid this
image.jpgimage.jpg

Then I discovered this
image.jpg

I was amazed when I finally got it back together and it actually shifted trough all the gears!!!!! :thumbsup:
It was so smooth and when I let off the throttle it actually stayed enGaged instead of dropping into neutral. It shifts smoothly from 1-2 and it goes into overdrive. I still can't believe I took it apart and put it back together and it runs so well!!!!!

Thanks everyone for the help! :tiphat
 
Well, celebrated too early. Took it for a good drive this morning and when it warmed up it was same ole same ole, hard shift and no overdrive. I guess I am going to put it in the shop.

Bummed!!!!!!!! :mad2:
 
Ok, I read on another forum that it could be brake light switch and the TPS. So in a last ditch effort I swapped out both and what do you know.... Fixed it. I took it for a long drive and got it good and warm, no problems. It shifts so smoothly and actually goes into OD nicely!
 
I'm having a similar problem with my 97 gmc k2500 6.5 shifts smoothly torque locks in 3rd but no overdrive according to solus scanner it's commanded, shows 4th but isn't actually in 4th pulling shifter back to 3rd has no change, still need to do another run test to get more data, im a new user for the scanner so have to learn what it's telling me any help would be appreciated
 
Fola1968 said:
I'm having a similar problem with my 97 gmc k2500 6.5 shifts smoothly torque locks in 3rd but no overdrive according to solus scanner it's commanded, shows 4th but isn't actually in 4th pulling shifter back to 3rd has no change, still need to do another run test to get more data, im a new user for the scanner so have to learn what it's telling me any help would be appreciated
Click to expand...
Also im new to the 6.5 and engine coolant temperature never seems to get above 165 degrees
 
You need to actually count the gears as it shifts. I'm not there but it sounds like you're missing lock up of the torque converter. Which would be caused by your low coolant temperature. IIRC Lock up won't happen until you reach 170*. It should lock up in both 3&4
 
4th is inhibited until engine temps reach 120 iirc, and trans temp is above 80. Lockup is also temp inhibited to both a few degrees warmer. If 4th is commanded and not going in, then there is an issue either in the valve body not sending pressure or in the actual overdrive clutch itself. You could have also broken the overdrive feed bolt and just dumping the fluid to the pan. If you command it to go into 4th and it doesn't, then you need to drop the valve body and check the bolt for the overdrive feed.
 
THEFERMANATOR said:
4th is inhibited until engine temps reach 120 iirc, and trans temp is above 80. Lockup is also temp inhibited to both a few degrees warmer. If 4th is commanded and not going in, then there is an issue either in the valve body not sending pressure or in the actual overdrive clutch itself. You could have also broken the overdrive feed bolt and just dumping the fluid to the pan. If you command it to go into 4th and it doesn't, then you need to drop the valve body and check the bolt for the overdrive feed.
Click to expand...
Appreciate all the info just being able to get back to the truck know, figured i would share little bit more info of what the transmission is doing, first off did have a service accelerator pedal sensor, checked with the scanner and it did have a sometimes dead spot in the voltage on the scanner on one feed sometimes 2 feeds at just above idle, the are that it would be spending most of it's time, changed that, drove it around local about 15 miles hasn't came back, before changing it sometimes it seem to have a engine miss in that position move the pedal little bit it went away, so that is not present anymore, changed the brake light switch, after that, even though switch positions checked fine on the scanner, still no 4th gear ,but torque does lock on it's own and manually, with scanner, all solenoids show the correct position on the scanner, with each gear selector position, even shows the correct gear ratio, while moving only, if remember correctly, even the 4th gear ratio, but at 45 to 55 mph level ground light throttle moving gear selector from overdrive to 3rd changes no engine rpm except torque unlock and relock ,and solenoid changes, gear ratio changes, at 65 mph rpm is around 3k ,down hill throttle at idle coasting around 55 selector in OD rpm around 900 move selector to 3rd rpms move up to around 1250 ,also while level ground light throttle torque locked 3rd or OD selected tap the brake torque doesn't unlock, not sure if supposed to, i believe the 4l60e in my 1500 did, that's about it 1st 2nd and 3rd shifts are normal
 
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