Question about GMC Cars & Trucks
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Posted on Jan 02, 2017
i have heard that the ignition switch can be faulty and not let the full voltage thru to the electricaly controlled 4l60e trans.i have the same problem with my 95 1/2 t. i rigged a switched wire from the fuse block via a relay to the proper wire on the trans....ask a trany tech and they will know what im talking about,,,good luck
Posted on Oct 30, 2008
Most likely the o-ring seal between the torque converter and the transmission is going bad. Get that transmission rebuilt pronto before serious damage is done! But first, have a mechanic drop the transmission pan and look for signs of a very thin silvery film coating the inside of the pan. If found, then the transmission definitely will have to be rebuilt, and the torque converter will also have to be replaced since embedded metallic particles in the old torque converter will eventually come loose, due to wear of the clutch plates within the torque converter, and eat up the rebuilt transmission. Now, here is the deal once the transmission has been rebuilt:
Change the transmission fluid and filter once a year -- no matter what! If you do this, then you should never have any more problems with the transmission.
Posted on Apr 20, 2009
I had this exact problem on my 2005 5.3L Suburban... It would shift into 1 and 2 and reverse, but not 3 and 4.
I took it into a transmission shop, and he said the 3-4 shift solenoid was burned up. Wanted 1500 to fix it. Far from home, so I have to pay it.
Posted on May 31, 2009
SOURCE: 1996 gmc jimmy will not
Hi, It may be in LIMP mode.
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.
Common failures on 4L60E, symptom any possible repair:
Trans shifts into gear harshly, car feels sluggish off the line, No 1st, 4th or TCC lockup available, Manual 2nd, 3rd and Reverse are only available gears, CEL is on: Transmission is either in limp-home mode or has lost electrical power. If there are lots of error codes in the PCM, check the under-hood fuse that powers the transmission, and if it pops again, look for a short in that circuit like an O2 sensor harness touching exhaust. Otherwise, check PCM codes for a particular fault in the transmission causing the PCM to put it in limp-home mode.
No 1st or 4th available; trans shifts 2nd to 3rd by itself in D or OD and locks the converter :ShiftA solenoid failed. Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM.
Car goes into gear but feels very sluggish like the brakes are dragging, but it will roll easily (starts out in 4th gear), you manually shift to 2 to get it moving, once it's moving you put it back in OD and the car shifts 3rd to 4th on its own and locks the converter at the appropriate time: ShiftB solenoid failed: Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM.
Trans seems noisy when moving in 1st and Reverse, noise goes away instantly if you shift to N or the trans goes into 3rd gear: Reaction planetary is worn out due to high miles or insufficient lubrication. Not a critical failure, but not a good sign either. R&R sooner rather than later.
3rd gear starts, can manually shift through all gears. When car has been turned off for a bit, then back on it will run normally.: VSS dropoff w/ Hi-stall converter. The rpms are too high, but VSS is showing no movement. Happens after a tire burning take-off. Doesn't store a code, will not throw a CEL (I've heard that it will store a code if it happens 3 or more times). Cure: Reprogram PCM for VSS dropoff -- PCMforLess knows about it.
If you can get the Jimmy for no more then $500.00 and the engine sounds good and body is good, you may want to invest in the repair of the jimmy. Also note that to have a close look at the fuel line along the frame on the drivers side just by the back doors, the line is know to corroded there on all the SUV's
Posted on Sep 19, 2010
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