Heres A Tricky One- 01 2500hd

HDdave · December 29, 2007

2001 Silverado 2500HD 6.0 4l80E

I have had this problem for a while now, but I can't seem to figure out what is causing it. when driving around 60mph and up, the Torque converter clutch will not engage. I have had it looked at by a few small mechanics and they could make it engage with their scanners. I noticed a few new things yesterday that might help you guys get an answer for me. I recently got a Diablosport predator programmer. I had it plugged in while I was going down the highway so I could erase my SES code (random misfire) that comes on at around 60mph and up (kind of ironic because thats when the TCC doesnt work...). Every single time I would clear the code, the TCC would instantly engage. It would stay in for all ascents, but if there was any sort of decent it would randomly disengage, and if I tried to re-engage it, the tcc would pop out a few seconds after it engaged. I am absolutely clueless on what is causing the TCC not to work, and I have never heard of anyone else with this problem, and I would really like to get it fixed. I would appriciate any help, I am clueless.

thrasherff · December 30, 2007

Keep me posted on this I also have a 2001 2500HD 6.0L and I was thinking about buying a Diablosport programmer. I hope your problem and the programmer are not related.

Genuinefine409 · December 30, 2007

This may be way off but maybe your TPS isn't working right???? If the engine unlocks the converter clutch at a certian load% which is based on the TPS and if the TPS is sending a wrong signal maybe its unlocking all the time. did you look at the TPS on the scanner to see if it goes from 0-100% smoothly as you press the pedal down? with most scanners you can check this with the engine off(makes it nice). My brother '95 was having problems with something i can't remember what but the TPS would jump from 6% to like 48% and was causing problems.

gmtech4 · December 31, 2007

This may be way off but maybe your TPS isn't working right???? If the engine unlocks the converter clutch at a certian load% which is based on the TPS and if the TPS is sending a wrong signal maybe its unlocking all the time. did you look at the TPS on the scanner to see if it goes from 0-100% smoothly as you press the pedal down? with most scanners you can check this with the engine off(makes it nice). My brother '95 was having problems with something i can't remember what but the TPS would jump from 6% to like 48% and was causing problems.

hi guys,you diag'd it yourself,what is happening is when the DTC is tripped ,the TCC is defaulting to not working,so when you clr the code it works till the code tripps again,get the code fixed,take it to a dealer,all DTCs have a extensive list of what happenes when a code is active,in our GM service information,good luck,i looked at your code for a missfire,take it to a driveabilty tech at a dealer,possible plugs,fuel filter,leaking intake manifold gasket,bad fuel,,good luck

HDdave · December 31, 2007

I've checked the TP sensor and I believe it is working correctly. I've changed plugs/wires, fuel filter, and it has been doing this for over a year now since I got the truck and I never thought much of it, so its not bad gas. I didn't think of the intake gasket, I am worried that my injectors are crap.. So what your saying is that the misfire is what is causing the TCC not to engage, and if I get the misfire fixed then the TCC should work correctly? That makes sense to me, I am just making sure..

also- The TCC will lock on its own on back roads at low speeds (40-50), but it will never lock on the highway. I am also curious why it would always pop out and the code come on as soon as I started downhill? Do you have any input on that?

thrasheff- the problem is definetly not tuner related, if anything, the tuner has helped me figure it out. I am impressed with what the Diablosport did to my truck, and would reccomend buying one if you are interested. Tbyrne motorsports has the best prices I have ever seen on one..

I really appriciate the help guys! This problem has been eating at me for quite some time...

gmtech4 · January 1, 2008

I've checked the TP sensor and I believe it is working correctly. I've changed plugs/wires, fuel filter, and it has been doing this for over a year now since I got the truck and I never thought much of it, so its not bad gas. I didn't think of the intake gasket, I am worried that my injectors are crap.. So what your saying is that the misfire is what is causing the TCC not to engage, and if I get the misfire fixed then the TCC should work correctly? That makes sense to me, I am just making sure..

also- The TCC will lock on its own on back roads at low speeds (40-50), but it will never lock on the highway. I am also curious why it would always pop out and the code come on as soon as I started downhill? Do you have any input on that?

thrasheff- the problem is definetly not tuner related, if anything, the tuner has helped me figure it out. I am impressed with what the Diablosport did to my truck, and would reccomend buying one if you are interested. Tbyrne motorsports has the best prices I have ever seen on one..

I really appriciate the help guys! This problem has been eating at me for quite some time...

Ijust looked up p0300,I did not not see that it disables TCC,but it is happening you said,it is a fairly involved diag table,and it is hard to feel TCC engagment because it is PWM,meaning it is ramped on,no like old trannies,good luck dave

rgriffin · February 2, 2011

Hello,

I have a 2002 2500HD that is having the exact same issue. The torque convertor will unlock once I get up to expressway speed (70mph) and it will not re-engage until I hit about 85mph. I only drove 85 to see what would happen once the truck hit over 3000 rpm. I can not get the lock-up between about 68-75mph where I do most of my driving. Any new information after 3 years?