I'm new to this forum. This is actually my first post. I have a 1996 GMC Sierra Z71 that is having tranny problems. Mechanic said it needs to be rebuilt and he'd do it for 1200. I got 2 questions. First is what kind of tranny do i have in my pickup. 4L60e or 4L80e? I ask because i'm thinking of buying a used one off ebay or something but i need to know what kind to get. Also what is the average cost to getting one rebuilt? 1200 a good or bad deal? Thanks guys.
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Transmission problem!
- Thread starter ortega90
- Start date
Sam Chicklets
New member
check at the local auto wreckers, or online buy/sell sites like Kijiji etc.
epiphaknee
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Is it the 4L60E or the 4L80E? 4L60E's are plentiful in wrecking yards. With a lot of Cash for Clunkers having the 4L60E, it's not hard to find one. They go for between $50.00 to about $300.00.
Molson02536
New member
Note that many problems that show up as transmission issues are actually PCM or electrical, and may be external to the transmission. Try a different PCM, and check for chafing where the cables come out of the PCM and touch the LF fenderwell.
ALL ELECTRICAL PROBLEMS ON THE B/D-BODY 4L60E CAN BE FIXED WITHOUT REMOVING THE TRANSMISSION.
put a line pressure gauge ($55 shipped on Ebay, or visit a local trans shop) on the pressure test port and go for a drive to verify proper line pressure. Base pressure at idle in P,N,OD should be around 70psi and around 140psi in R. Max line pressure should be at least 190psi at WOT in 1st or 2nd, 225psi is optimum. If base pressure is low, trans or pump is worn out. If max pressure is low, check EPC solenoid. If reverse is slow to engage, and line pressure does not come up to at least 130psi in reverse, replace the boost valve with a Transgo 0.500" boost valve (easy fix in pan).
What is "limp-home mode" ? This is a fault mode in which the transmission either loses electrical power or the PCM deactivates all of the electronics. The transmission will default to max line pressure. The driver will have Reverse and 3rd, with manual 2nd available by putting the gearshift in 2 or 1 (doesn't matter). 1st, 4th, and TCC lockup will not be available. It will not hurt the car to drive it like this for short periods, but use manual 2nd to get the car moving, and be aware that the trans will generate more heat than normal while operating in limp-home mode due to increased torque converter slippage during 2nd gear starts and no lockup in 3rd gear.
Keep me posted and let me know what transmission issues you may have. Common problem is the wire harness clip on the transmission passenger side "4L60E" corrode and wires break being next to the catalytic converter and the wire clip on the 4L80E is on the drivers side. The other thing to is the boost valve to be worn out and that $45,00 part and easy fix when pans is dropped, dirty transmission oil and filter. The 4L60E is a low viscosity transmission, as the dirt raises the viscosity. Fluid retention rises causing the check valve in the valve body and the electronic pressure control valve (EPC)sticks. Good luck and start with the simple and have the transmission road tested with the transmission line pressure gauge hooked up to get a proper reading throughout the function of all the gears. The other common thing to is a bad Throttle position Senor (TPS), bad TPS will create poor transmission performance and shifting patterns. Keep me posted friend.
ALL ELECTRICAL PROBLEMS ON THE B/D-BODY 4L60E CAN BE FIXED WITHOUT REMOVING THE TRANSMISSION.
put a line pressure gauge ($55 shipped on Ebay, or visit a local trans shop) on the pressure test port and go for a drive to verify proper line pressure. Base pressure at idle in P,N,OD should be around 70psi and around 140psi in R. Max line pressure should be at least 190psi at WOT in 1st or 2nd, 225psi is optimum. If base pressure is low, trans or pump is worn out. If max pressure is low, check EPC solenoid. If reverse is slow to engage, and line pressure does not come up to at least 130psi in reverse, replace the boost valve with a Transgo 0.500" boost valve (easy fix in pan).
What is "limp-home mode" ? This is a fault mode in which the transmission either loses electrical power or the PCM deactivates all of the electronics. The transmission will default to max line pressure. The driver will have Reverse and 3rd, with manual 2nd available by putting the gearshift in 2 or 1 (doesn't matter). 1st, 4th, and TCC lockup will not be available. It will not hurt the car to drive it like this for short periods, but use manual 2nd to get the car moving, and be aware that the trans will generate more heat than normal while operating in limp-home mode due to increased torque converter slippage during 2nd gear starts and no lockup in 3rd gear.
Keep me posted and let me know what transmission issues you may have. Common problem is the wire harness clip on the transmission passenger side "4L60E" corrode and wires break being next to the catalytic converter and the wire clip on the 4L80E is on the drivers side. The other thing to is the boost valve to be worn out and that $45,00 part and easy fix when pans is dropped, dirty transmission oil and filter. The 4L60E is a low viscosity transmission, as the dirt raises the viscosity. Fluid retention rises causing the check valve in the valve body and the electronic pressure control valve (EPC)sticks. Good luck and start with the simple and have the transmission road tested with the transmission line pressure gauge hooked up to get a proper reading throughout the function of all the gears. The other common thing to is a bad Throttle position Senor (TPS), bad TPS will create poor transmission performance and shifting patterns. Keep me posted friend.