1995 Tahoe - reverse doesn't work

[snowmass2dr]

My brother and I just picked up a 1995 Tahoe, the issue, reverse doesn't work. It shifts into reverse and you can rev the engine without hearing any grinding, screeching, etc, there is just no power. All other gears work fine and the truck drives forward great, lots of power, shifts smoothly. Not sure if it's electrical, (the brake lights don't seem to work) a linkage issue, or something greater in the tranny. Any help would be great, my brother and I have decent mechanical ability and are willing to tackle just about anything, hence buying (cheaply) a vehicle that only goes one direction. Thanks in advance.

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[SabrToothSqrl]

I'd guess it's the tranny, but that's a guess.

in PA you need reverse to pass inspection (who knew!?)

[LARIDERS]

I know alot of times the reverse shell goes out in the 4l60e trans.

[cooter26]

Common failures on 4L60E, problems any possible repair

Problem		Symptoms		Possible repair
Slow, slipping or no reverse		“lo-reverse” clutches are worn out, fluid leak in the reverse apply circuit, or broken sunshell.. May also have worn boost valve.		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 Transmissionmission additive or other seal restorer product.
1-2 shift does not happen at WOT until you let off the gas		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).		Try replacing the ThrottlePosition Sensor ThrottlePosition Sensor (TPS).
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.
1-2 shift is delayed and harsh, may not shift into Over Drive		CheckThrottlePosition Sensor (TPS).for smooth and linear electrical response over the entire range of motion.		If not, replace.
Transmission does not upshift out of first, speedometer reads zero at all times Speed Sensor (VSS) failure.		Cross member must come out to access Speed Sensor (VSS).		Easy fix on rear of Transmissionmission,
Will not work in 3rd or 4th gear		“3-4” clutches are worn out. The car is safe to drive (in 2nd) until you can get it fixed.		Remove & replace or rebuild
Sudden grinding noise with no prior warning primarily in 2nd gear, behavior in reverse may be abnormal		sunshell is fractured. Try not to run or drive the car or further damage could result.		Remove & replace or rebuild
1st and 3rd only, will not work in 2nd ,4th or Reverse		sunshell is fractured or splines are sheared off. Try not to run or drive the car or further damage could result.		R&R
Will not work in 2nd or 4th gear		2-4 band is slipping. Servo seals may be damaged (can be fixed without removing Transmission. Otherwise, 2-4 band is worn out.		Remove & replace or rebuild
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		Transmissionmision 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 Transmissionmission, 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 Transmissionmission causing the PCM to put it in limp-home mode.		check the underhood fuse that powers the Transmissionmission
Will not work in 1st or 4th available Transmission shifts 2nd to 3rd by itself in Drive or Over Drive and locks the converter		ShiftA solenoid failed. Or a wiring problem from PCM to Transmission.. or PCM.		Easy fix in the pan.
Transmissionmission 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		Shift B solenoid failed. Or a wiring problem from PCM to Transmission.. or PCM.		Easy fix in the pan
No Torque Converter Control (TCC) lockup		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		(must remove Transmission and replace TC).
Torque Converter Control (TCC) always locked		Torque Converter Control (TCC) apply solenoid circuit shorted to ground, Torque Converter Control (TCC) solenoid blockage.		Easy fix by removing the pan. or Torque Converter is damaged (must remove Transmission and replace TC).
Loud noise in 4th gear 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.		Remove & replace or rebuild
Soft shifting, gradual performance degradation		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.		Also try a Transmissionmission flush with BG brand products if problem continues, probably R&R
No forward movement in OD or D, but L2, L1 and R work		Forward sprag is broken.		Remove & replace or rebuild Try not to run or drive the car or further damage could result.
Extremely harsh shifts from P or N, normal shifts at WOT		Electronic Pressure Control (EPC (Electronic Pressure Control) solenoid failed.		Easy fix in pan. Fix as soon as possible or hard parts will eventually break.
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.		Remove & replace or rebuild
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		Reaction planetary is worn out due to high miles or insufficient lubrication. Not a critical failure, but not a good sign either.		Remove & replace or rebuild sooner rather than later.
No movement in any gear		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.		Remove & replace or rebuild, or refill pan and find the leak.
Transmissionmission does not shift automatically, only manually.		Check wiring, check other sensors such as Speed Sensor (VSS) andThrottlePosition Sensor (TPS)..		Swap in a known-good PCM,
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.		Speed Sensor (VSS) dropoff 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.		Reprogram PCM for Speed Sensor (VSS) dropoff
Fluid leak out of the front of Transmission where the converter connects partial or full loss of movement		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		Remove & replace or rebuild
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 Torque Converter Control (TCC) hydraulic circuit are worn, replace the torque converter.		Lubegard Shudder Fix will at least fix this for awhile. Or try a Transmissionmission flush by a shop that uses BG brand products.
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		CheckThrottlePosition Sensor (TPS).for smooth electrical response. If the response is jumpy or erratic at all.		replaceThrottlePosition Sensor (TPS)..
Fluid pumped out through the vent tube		Plugged cooler line.		Flush the Transmissionmission cooler and cooler lines. Also could be overfiled Transmissionmission.
Transmissionmission 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		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.		Remove & replace or rebuild
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. Transmission will eventually die a loud, catastrophic death. Cheaper to rebuild now (saves further damage to hard parts). It is drivable until it breaks.		Remove & replace or rebuild
1-2 or 2-3 shift is slow/soft above part throttle		Transmissionmission is failing.		Remove & replace or rebuild

Before guessing at Transmissionmission problems, check the fluid level (car warmed up, engine running in Park on level ground) and have the PCM scanned for trouble codes FIRST. This guide is meant for problems that do not show up as PCM codes (like shift A&B solenoid failures, for example).

NOTE The Transmissionmission is on the same fuse as the MAF, O2 sensors and at least one other sensor - if an O2 shorts out, it will blow the fuse and the Transmission will go into limp-home mode. Be sure the Transmission has power and the fuse is not blown before doing anything else.

Also note that many problems that show up as Transmissionmission issues are actually PCM or electrical, and may be external to the Transmissionmission. Try a different PCM, and check for chafing where the cables come out of the PCM.

Secondly, put a line pressure gauge ($55 shipped on Ebay, or visit a local Transmission 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, Transmission or pump is worn out. If max pressure is low, check Electronic Pressure Control (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 by removing the pan.

Beware of coolant contamination - coolant will cause clutch packs to delaminate and thus cost you a rebuild! Transmission fluid eats radiator hoses! If you find any sign of cross contamination, fix the problem and thoroughly flush both systems IMMEDIATELY.

What is "limp-home mode" ? This is a fault mode in which the Transmissionmission either loses electrical power or the PCM deactivates all of the electronics. The Transmissionmission 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 Torque Converter Control (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 Transmission 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.



Generic GM Automatic Transmission Codes
Without Onboard Diagnostics (OBD-II)

Code		Problem		Code	Problem
21		TPS circuit		66	3-2 Control solenoid circuit fault
22		TPS out of adjustment		67	Torque Converter Control (TCC) solenoid circuit
28		Transmissionmission range pressure switch		69	Torque Converter Control (TCC) stuck on
31		park/neutral switch		72	Speed Sensor (VSS) circuit loss Transmissionmission output signal
36		Transmissionaxle shift control (3.8L)		73	Transmission pressure control solenoid
37		brake switch(4L60-E Transmission)		79	Transmissionmission fluid temp high
39		Torque Converter Control (TCC) knock sensor shorted(4.3L)		81	Transmissionmission 2-3 error
58		Transmission code-TTS temp high		82	Transmissionmission 1-2 error
59		Transmission code-TTS temp low		83	Torque Converter Control (TCC) solenoid circuit fault

How to get Trouble Codes
Turn ignition switch to OFF position
Locate Data Link Connector (DLC), see image below.
Jumper the A&B terminals(a paper clip or a jumper wire work ok)
Turn Ignition switch to ON position.
Count the flashes on the "CHECK ENGINE" or "SERVICE ENGINE" light.
FLASH, pause, FLASH, FLASH = code 12
NOTE: Some 94 & 95 models do not have the B terminal. In which case a scanner is required.
NOTE: Some 94 & 95 models that DO have the A & B terminals still require a scanner.
All vehicles after 96 are OBDII,and require a scanner to access them.
12 Pin Data Link Cconnector (under dash)

A - Ground		F - Torque Converter Control (TCC)
B - Test Terminal		G - Fuel Pump
C - Air Injection		H - Brake Sense Speed Input
E - Serial Data		M - Serial Data

Clearing Trouble Codes


Diagnostic trouble codes may be cleared by disconnecting the battery ground cable for at least 20 seconds. Reconnect negative battery cable and recheck codes to confirm the repair.

[snowmass2dr]

Thanks, I'll start with checking the pressure and see what that shows me.

[snowmass2dr]

Update - So my brother says with enough throttle it will creep in reverse - does this sound more like a pressure/pump issue? If the sun shell is gone would it still be able to move slightly? Thanks - still trying to find some pressure testing equip.