4l60 Common Problems

[Mr.38L]

Common failures on 4L60E, symptom < cause > any
possible repair:
1. Slow, slipping or no reverse: “lo-reverse” clutches are worn out, fluid leak in the reverse
apply circuit, or broken sunshell. It is possible to
remedy a fluid problem by removing the checkball
from its cage in the case in the rear of the trans may
help (must remove valvebody), or adding a high-
viscosity additive such as Lucas Transmission additive or other seal restorer product. May also
have worn boost valve (can replace in the pan).
2. 1-2 shift does not happen at WOT until you let off the gas: Best case: try replacing the TPS. Middle case: leak in the 2nd gear apply circuit
(servo assembly or 1-2 accumulator). Doublecheck
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).
3. 1-2 Shift shudder at WOT; delayed or abnormal 1-2 shift; There's a problem ONLY on the 1-2 shift: 1-2 accumulator piston cracked or stuck cocked in the bore. 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.
4. 1-2 shift is delayed and harsh, may not shift into OD: Check TPS for smooth and linear electrical response over the entire range of motion. If not,
replace.
5. Trans does not upshift out of first, speedometer reads zero at all times: VSS failure. Easy fix on rear of transmission, but xmember must
come out to access VSS.
6. No 3rd or 4th gear: “3-4” clutches are worn out. R&R. The car is safe to drive (in 2) until you can get
it fixed.
7. Sudden grinding noise with no prior warning primarily in 2nd gear, behavior in reverse may be
abnormal; sunshell is fractured. R&R. Try not to run
or drive the car or further damage could result.
8. 1st and 3rd only, no 2,4 or R; sunshell is fractured or splines are sheared off. R&R. Try not to
run or drive the car or further damage could result.
9. No 2nd or 4th gear. 2-4 band is slipping. Servo seals may be damaged (can be fixed without
removing trans. Otherwise, 2-4 band is worn out.
R&R.
10. 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: Transmision is either in
limp-home mode or has lost electrical power. If
there are lots of error codes in the PCM, check the
underhood 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.
11. 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.
12. 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. 13. No TCC lockup: Brake pedal switches improperly adjusted (always on), TCC solenoid
failed (easy fix in the pan), TCC clutch worn out
(must remove trans and replace TC).
14. TCC always locked: TCC apply solenoid circuit shorted to ground, TCC solenoid blockage (easy fix
in pan), or TC broken (must remove trans and
replace TC).
15. Horrible noise in 4th and feels like the brakes are on: 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. R&R.
16. Soft shifting, gradual performance degradation: Poor line pressure rise due to leaking boost valve, clogged EPC filter screen, failing EPC
solenoid, or worst case: leaky seals throughout.
Transgo HD2-C kit fixes first two without removing
trans. Seal restorer may fix last problem, but
probably R&R. Also try a transmission flush with BG
brand products (Firestone stocks it). 17. No forward movement in OD or D, but L2, L1 and R work: Forward sprag is broken. R&R. Try not to run or drive the car or further damage could
result.
18. Extremely harsh shifts from P or N, normal shifts at WOT: EPC (Electronic Pressure Control) solenoid failed. Easy fix in pan. Fix as soon as
possible or hard parts will eventually break.
19. Loud bang, grinding sound, loss of all gears, and a binding driveshaft: snapped output shaft. Try to wiggle driveshaft - if more than 0.020" play,
that's the sign. R&R.
20. 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.
21. No movement in any gear: pump failure, or total loss of fluid. R&R, or refill pan and find the
leak. If out of fluid, avoid running the engine until
the trans 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.
22. Transmission does not shift automatically, only manually . Swap in a known-good PCM, check wiring, check other sensors such as VSS and
TPS.
23. 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. 24. Fluid leak out of the front of trans where the converter connects; partial or full loss of movement: Front pump bushing walked out. R&R. May have to replace converter also if hub is scored.
Note that a leaking front seal usually means the
bushing is walking out (i.e. call your local trans
shop and schedule an appt.).
25. Torque converter shudder in 4th while lockup is engaged; problem goes away when the brake pedal is pressed slightly to unlock converter.
Have a shop verify line pressure, and provided no
valves in the TCC hydraulic circuit are worn, replace
the torque converter. Also, Lubegard Shudder Fix
will at least fix this for awhile. Or try a transmission
flush by a shop that uses BG brand products. 26. Shift 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. Problem may be intermittent: Check TPS for smooth electrical response. If the response is jumpy or erratic at all,
replace TPS.
27. All fluid pumped out through the vent tube: Plugged cooler line. Flush the transmission cooler
and cooler lines. Also could be overfiled
transmission.
28. Car acts like it's in OD in neutral, car is locked stationary in R, engine feels loaded in P, all four forward positions work fine: R&R: Internal crossleak 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.
29. Needle bearings in the pan, first gear and/or reverse may be noisy: Either a torrington bearing or a planetary bearing is on its way out. Trans will
eventually die a loud, catastrophic death. Cheaper
to rebuild now (saves further damage to hard
parts), but requires R&R. It is drivable until it
breaks.
30. 1-2 or 2-3 shift is slow/soft above part throttle: Trans is on its way out. R&R.

[Mr.38L]

Will edit and clean it up a little bit when i get home and can access a computer

[Vee-ard]

Thanks for the info, and no offense but the link for one of many sites that you can get that info from is just easier, neater and has been posted up many times before.

eg: FYI 4L60E common problems / failures | GM Truck Headquarters

[Mr.38L]

Just thought it might be easier for others if it's on the forum mate but cheers anyway