Now that I've rebuilt a few of these transmissions now I'll throw up a list of problems that I've discovered for each and things I think would benefit them for long life. So far 700R4 was rebuilt because I did not know how to adjust the TV cable and I though trans was going out, 4L60E in blazer was rebuilt because of coolant in trans from accident, other 4L60E was rebuilt because of accumulator piston failure.

700R-4 150K miles ('87+ with aux. valvebody)
*TV cable adjustment - should probably be checked once a year to account for possible stretch.
*Forward, 1-2, and 3-4 accumulator pistons - these could be replaced every 100K miles and can be done in vehicle.
*VSS - Converter Lock-up

4L60E 130K and 314K miles
*Forward, 1-2, and 3-4 accumulator pistons - these could be replaced every 100K miles and can be done with transmission in vehicle.

Electrical components that affect transmission operation.
*VSS - shift timing
*Trans fluid temp - Converter Lock-up
*TPS - shift timing/line pressure/Converter Lock-up
*Engine RPM - shift timing/Converter Lock-up
*Coolant temp - Converter Lock-up
*Brake switch - Converter Lock-up; Unlocks when brakes are applied
*Fluid Pressure - Informs ECM what gear position shifter is in
*4w low switch - shift pattern; shifts earlier to prevent high engine RPMs
*AC request - line pressure/Converter Lock-up/shift timing
*Cruise Control - shift timing
*MAP - line pressure

** While I have the pan off for a fluid/filter change, I like to find someone with a TIG welder and add a bung for a drain plug. Saves time and a lot of mess. Not to mention lets you save and reuse fluid if you do a low mileage filter change or need to drain fluid for some reason.**

Shift Solenoid Operation:
Park- A ON, B ON
Rev.- A ON, B ON
Neu.- A ON, B ON
1st- A ON, B ON
2nd- A Off, B ON
3rd- A Off, B Off
4th- A On, B Off

 

This was taken from other sites and compiled into a nice hard to read list.

Problem: Slow, slipping or no reverse
Symptoms: “lo-reverse” clutches are worn out, fluid leak in the reverse apply circuit, or broken sunshell. May also have worn boost valve.
Possible repair: It is possible to remedy a fluid problem by removing the checkball from its cage in the case in the rear of the Transmission may help (must remove valvebody), or adding a high-viscosity additive such as Lucas Transmission additive or other seal restorer product.

Problem: 1-2 shift does not happen at WOT until you let off the gas
Symptoms: Middle case leak in the 2nd gear apply circuit (servo assembly or 1-2 accumulator). Double check by using the pressure gauge and watch for a big drop when the PCM commands 2nd gear. Worst case poor line pressure rise (see below).
Possible repair: Try replacing the Throttle Position Sensor(TPS).

Problem: 1-2 Shift shudder at WOT delayed or abnormal 1-2 shift There's a problem only on the 1-2 shift
Symptoms: 1-2 accumulator piston cracked or stuck cocked in the bore.
Possible repair: Check the yellow spring inside the accum housing for breakage. Also, if the accumulator housing walls are scored, the housing must be replaced. Easy fix in the pan.

Problem: 1-2 shift is delayed and harsh, may not shift into Over Drive
Symptoms: Check Throttle Position Sensor (TPS).for smooth and linear electrical response over the entire range of motion.
Possible repair: If not, replace.

Problem: Transmission does not upshift out of first, speedometer reads zero at all times Speed Sensor (VSS) failure.
Symptoms: Cross member must come out to access Speed Sensor (VSS).
Possible repair: Easy fix on rear of Transmission.

Problem: Will not work in 3rd or 4th gear
Symptoms: “3-4” clutches are worn out. The car is safe to drive (in 2nd) until you can get it fixed.
Possible repair: Remove & replace or rebuild

Problem: Sudden grinding noise with no prior warning primarily in 2nd gear, behavior in reverse may be abnormal
Symptoms: Sunshell is fractured. Try not to run or drive the car or further damage could result.
Possible repair: Remove & replace or rebuild

Problem: 1st and 3rd only, will not work in 2nd ,4th or Reverse
Symptoms: Sunshell is fractured or splines are sheared off. Try not to run or drive the car or further damage could result.
Possible repair: R&R

Problem: Will not work in 2nd or 4th gear
Symptoms: 2-4 band is slipping. Servo seals may be damaged (can be fixed without removing Transmission. Otherwise, 2-4 band is worn out.
Possible repair: Remove & replace or rebuild

Problem: Shifts into gear harshly, car feels sluggish off the line, No 1st, 4th or Torque Converter Control (TCC) lockup available, Manual 2nd, 3rd and Reverse are only available gears, CEL is on
Symptoms: 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.
Possible repair: Check the under hood fuse that powers the Transmission

Problem: Will not work in 1st or 4th available Transmission shifts 2nd to 3rd by itself in Drive or Over Drive and locks the converter
Symptoms: ShiftA solenoid failed. Or a wiring problem from PCM to Transmission... or PCM.
Possible repair: Easy fix in the pan.

Problem: Transmission goes into gear but feels very sluggish like the brakes are on, 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
Symptoms: Shift B solenoid failed. Or a wiring problem from PCM to Transmission... or PCM.
Possible repair: Easy fix in the pan

Problem: No Torque Converter Control (TCC) lockup
Symptoms: Brake pedal switches improperly adjusted (always on), Torque Converter Control (TCC) solenoid failed (easy fix in the pan), Torque Converter Control (TCC) clutch worn out
Possible repair: Must remove Transmission and replace TC

Problem: Torque Converter Control (TCC) always locked
Symptoms: Torque Converter Control (TCC) apply solenoid circuit shorted to ground, Torque Converter Control (TCC) solenoid blockage.
Possible repair: Easy fix by removing the pan. or Torque Converter is damaged (must remove Transmission and replace TC).

Problem: Loud noise in 4th gear and feels like the brakes are on
Symptoms: Overrun clutches are applying due to a cracked or leaking forward piston. Overrun clutches will be worn out after 30 seconds of this behavior. Car can be safely driven in D.
Possible repair: Remove & replace or rebuild

Problem: Soft shifting, gradual performance degradation
Symptoms: Poor line pressure rise due to leaking boost valve, clogged Electronic Pressure Control EPC filter screen, failing Electronic Pressure Control (EPC solenoid), or worst case leaky seals throughout. Transgo HD2-C kit fixes first two without removing Transmission. Seal restorer may fix last problem.
Possible repair: Also try a Transmissionmission flush with BG brand products if problem continues, probably R&R

Problem: No forward movement in OD or D, but L2, L1 and R work
Symptoms: Forward sprag is broken. Or assembled backwards if following a rebuild.
Possible repair: Remove & replace or rebuild Try not to run or drive the car or further damage could result.

Problem: Extremely harsh shifts from P or N, normal shifts at WOT
Symptoms: Electronic Pressure Control (EPC (Electronic Pressure Control) solenoid failed.
Possible repair: Easy fix in pan. Fix as soon as possible or hard parts will eventually break.

Problem: Loud bang, grinding sound, loss of all gears, and a binding driveshaft
Symptoms: Snapped output shaft. Try to wiggle driveshaft - if more than 0.020" play, that's the sign.
Possible repair: Remove & replace or rebuild

Problem: Transmission seems noisy when moving in 1st and Reverse, noise goes away instantly if you shift to N or the Transmission goes into 3rd gear
Symptoms: Reaction planetary is worn out due to high miles or insufficient lubrication. Not a critical failure, but not a good sign either.
Possible repair: Remove & replace or rebuild sooner rather than later.

Problem: No movement in any gear
Symptoms: Pump failure, or total loss of fluid. If out of fluid, avoid running the engine until the Transmission is refilled to avoid pump damage. To check for pump failure, check fluid level with the engine off, then start the engine and recheck fluid level. If level does not go down when engine is running, the pump is broken.
Possible repair: Remove & replace or rebuild, or refill pan and find the leak.

Problem: Transmission does not shift automatically, only manually.
Symptoms: Check wiring, check other sensors such as Speed Sensor (VSS) andThrottlePosition Sensor (TPS).
Possible repair: Swap in a known-good PCM

Problem: 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.
Symptoms: Speed Sensor (VSS) drop-off w/ Hi-stall converter. The RPMs are too high, but Speed Sensor (VSS) is showing no movement. Happens after a tire burning take-off. Doesn't store a code, will not throw a CEL.
Possible repair: Reprogram PCM for Speed Sensor (VSS) drop-off

Problem: Fluid leak out of the front of Transmission where the converter connects partial or full loss of movement
Symptoms: Front pump bushing walked out.May have to replace converter also if hub is scored. Note that a leaking front seal usually means the bushing is walking out.
Possible repair: Remove & replace or rebuild

Problem: Torque converter shudder in 4th while lockup is engaged
Symptoms: Problem goes away when the brake pedal is pressed slightly to unlock converter. Check fluid level. Have a shop verify line pressure, and provided no valves in the Torque Converter Control (TCC) hydraulic circuit are worn, replace the torque converter.
Possible repair: Lubegard Shudder Fix will at least fix this for awhile. Or try a Transmission flush by a shop that uses BG brand products.

Problem: Shifting suddenly become very hard. When going from park to either reverse or drive it slams into gear. 1-2 and 2-3 shifts are also harsh. All gears seems to work. May be intermittent
Symptoms: Check Throttle Position Sensor (TPS).for smooth electrical response. If the response is jumpy or erratic at all.
Possible repair: Replace Throttle Position Sensor (TPS).

Problem: Fluid pumped out through the vent tube
Symptoms: Plugged cooler line.
Possible repair: Flush the Transmission cooler and cooler lines. Also could be overfilled Transmission.

Problem: Transmission acts like it's in Over Drive in neutral, car is locked stationary in Reverse, engine feels loaded in ark,, all four forward positions work fine
Symptoms: Internal cross-leak feeding the forward clutches all the time. Most likely a cracked input housing, or cracked forward piston means forward clutches are fused together. Car can safely be driven gently in forward gears until the repair.
Possible repair: Remove & replace or rebuild

Problem: Needle bearings in the pan, first gear and/or reverse may be noisy
Symptoms: Either a torrington bearing or a planetary bearing is on its way out. Transmission will eventually die a loud, catastrophic death. Cheaper to rebuild now (saves further damage to hard parts). It is drivable until it breaks.
Possible repair: Remove & replace or rebuild

Problem: 1-2 or 2-3 shift is slow/soft above part throttle
Symptoms: Transmission is failing.
Possible repair: Remove & replace or rebuild

 

Transmission installation tips:

After a rebuild or installing a transmission that is completely empty of fluid and a torque converter that is new or has been emptied, I have started this procedure and it's worked out well so far. Not like the times when I did not do this.

1. Fill trans until dipstick reads full.
2. Jack up vehicle and put on stands so drive wheels are off the ground. At minimum 2" just in case.
3. Start vehicle and leave in PARK.
4. Check fluid level again and add if required... granted the measurement will be off since vehicle is not level.
5. Shift into normal Drive range and let off brake.
6. Ease into throttle to slowly run transmission through all the gears. Make sure to watch the tachometer or listen/feel the vehicle for the shifts to make sure all the gears work. This should also be evident by carefully watching the tach.
7. Run through all the gears multiple times.
8. !!!!APPLY BRAKES!!!! and put vehicle in PARK.
9. Turn off engine and lower vehicle to the ground.
10. Check fluid level and if proper, proceed with test drive. I try to stay close to home or roads with little to no traffic should something happen.

 

A lot of good information here. I have a question for you as well. Recently my truck was very slugglish at anything over half throttle. I unplugged the MAF sensor and it runs good now (swapping MAFs with a buddy tonight to see if mine is bad) but the transmission is shifting hard on the 1-2, 2-3 shift. Could unplugging the MAF cause this? I also have somewhat of a harsh shift into reverse or drive at times.

 

The MAF could very well affect shift timing/line pressure as well.
I believe the MAF/MAP work together to calculate fuel requirements based upon air taken in vs. vacuum. You probably have hard shift points because the engine enters a "limp" mode or 'default' where it runs based on factory setpoints for spark and fuel tables(was stuck as school one day and an automotive student suggested unplugging MAF to get by... MAF was completely dead in that case). With the MAF plugged in it can use O2 sensors and MAF/MAP to calculate and adjust fuel.

 

Man this is a good thread. But darn it for presenting new possibilities for my issues. My trans won't shift into reverse right away and only slips just enough to get me out parking spaces. And it won't engage overdrive more more than 5 seconds at a time. I figured the problem was just 212k miles on it and was an internal wear issue. Now i see it could be a TPS or something i just just replace win my garage. Good and bad i guess. Anyone out there ever have these symptoms? What was the problem? The Jimmy is just my winter beater, but in northern WI, i can't afford to be without it and would love to narrow my options before the spring comes around.

Thanks in advance.

 

Good information for sure! I gathered up the problems/symptoms/possible fix info quite some time ago from a few different sources here --> 4L60E Information & Common Problems - Compilation

 

I figured it was on here, but I've learned in my 10 years of forums is that no matter what forum you are on the search never gets used as much as it should... lots of information on here and other places but threads with a bad thread label really throws a guy off. I probably should have called this one something else.

I really just wanted to put it up for the electronics that affect shift operations. I'm sure there are way more shift-kits installed because something else is causing a problem.
I rebuilt my first 700R4 because it "seemed weak" and just needed a TV cable adjustment. Now it has just about everything but 5-pinion planetarys.

 

good info here. also you should add another potential problem: pumping whining noise once transmission gets hot. cause: pump starving for fluid. Remedy: clogged EPC filter screen, clogged fliter on separtor plate, bad or failing EPC solenoid, clogged tranny filter or dirty valve body...

 

Some good info right here. Explains why my Blazer slams 2nd gear so hard.