Issue Summary:
- Before or after overhaul, Volkswagen/Audi vehicles equipped with the 01M transaxle may exhibit no forward engagement or a slipping condition on take-off in first gear.
- Beginning at the start of production for 1999 models, all THM 4L80-E transmissions were built with a revised manual-2nd band that is wider than the previous design.
- Beginning at the start of production for all 1999-model THM 4L80-E transmissions, the planetary pinions on both carriers were produced 10% thicker than in the previous models.
- Some 1995-96 Buick Century and Oldsmobile Ciera vehicles equipped with the 3.1-liter engine and the THM 4T40-E transaxle may exhibit a condition of third-gear starts and the air conditioner not working.
- Some 1993-95 Cadillacs equipped with the THM 4T80-E transaxle may illuminate the Service Engine Soon lamp and store P080 as a current code. After you try to clear the code, it remains as a hard code.
- Before and/or after rebuild of a THM 4T40-E, the vehicle illuminates the Check Engine lamp and stores code P1887 or P0742 in memory.
Before or after overhaul, vehicles equipped with the 01M transaxle may exhibit no forward engagement or a slipping condition on take-off in first gear.
The cause may be that the K1 (forward) piston is cracked (see Figure 1), which can cause a loss of forward-clutch pressure.
Replace the K1 (forward) piston as part of every overhaul.
At the time of this printing, Volkswagen does not supply the K1 (forward) piston separately from the complete drum assembly. Aftermarket suppliers have available a piston kit to service the K1 drum and all the other bonded pistons.
Beginning at the start of production for 1999 models, all THM 4L80-E transmissions were built with a revised manual-2nd band that is wider than the previous design (see Figure 2).
Improved durability and reliability.
Manual-2nd band – Now 11⁄4 inches wide instead of the previous 1 inch, and manufactured with a revised band-apply-pin anchor (see Figure 3).
The new-design wide band will retrofit, but you must buy the new-design band-apply pin that is 0.200 inch longer than the previous design. Currently, it is available only in a service package that includes the piston and the return spring, under part number 24223081 (see Figure 3).
- Narrow manual-2nd band . . . . . . . . . .24202631
- Wide manual-2nd band . . . . . . . . . . . .24210080
- Apply-pin service package (narrow band) . . . . . . . . . . .24200418
- Apply-pin service package (wide band) . . . . . . . . . . . .24223081
Special Note:
- If the wide band is used with the apply pin for the narrow band, the result will be no engine braking when the selector lever is moved to the manual-2nd position, because the apply pin is not long enough to apply the band.
- If the narrow band is used with the apply pin for the wide band, the result will be second-gear starts, tie-up on the 2-3 shift and tie-up in reverse, since you have mechanically applied the band because of the length of the pin.
Beginning at the start of production for all 1999-model THM 4L80-E transmissions, the planetary pinions on both carriers were produced 10% thicker than the previous models (see Figure 4). This engineering change required the addition of a 0.041-inch shim in the geartrain to re-center the sun gear in the new planetary pinions and affected several internal parts that may create some confusion and thus some misassembly concerns.
Increased durability and reliability.
Planetary pinion gears – Were increased in length by about 0.075 inch in both front and rear carriers, as shown in Figure 4, for increased durability.
Added 0.041-inch shim – A 0.041-inch shim was added between the thrust bearing and the rear internal ring gear to re-center the sun gear in the revised planetary pinion gears (see Figure 5).
Center support – Required a 0.041-inch recess to be machined into the center-support bearing surface to accommodate the sun gear being re-centered in the revised planetary pinion gears (see Figure 6).
Sun-gear shaft – Required removal of 0.041 inch from the bottom of the rear bushing journal to accommodate the re-centering of the sun gear in the revised planetary pinion gears (see Figure 7).
Notice that revised sun-gear shaft can be identified by a groove cut into the shaft splines (see Figure 7).
None of the parts listed above will interchange with any of the previous-design-level parts, and none of the previous-design-level parts can be used in the 1999 and later units.
However, when all pieces listed are used as a service package, they can be used to back-service center-lube model 4L80-E transmissions.
The sun gear, mainshaft, rear internal ring gear and all thrust bearings remained the same (see figures 8, 9, and 10).
Special Note:
Figure 11 shows some examples of incorrect assembly and provides some dimensional checks to prevent this from happening to you.
- Reaction (front) carrier assembly (99 design level) . . . . . . . . . 24202051
- Output (rear) carrier assembly (99 design level) . . . . . . . . . . . 24202052
- Washer, 0.041 inch (99 design level) . . . . . . . . . . . . . . . . . . . 24211821
- Center-support assembly (99 design level) . . . . . . . . . . . . . . . . 24217454
- Sun-gear shaft assembly (99 design level) . . . . . . . . . . . . . . . . 24207264
Some 1995-96 Buick Century and Oldsmobile Ciera vehicles equipped with the 3.1-liter engine may exhibit a condition of third-gear starts and the air conditioner not working. Since the vehicle came into a transmission shop, we immediately check for voltage at terminal “E” at the case connector and find 0 volts. After inspecting the fuse block, you discover that there are no blown fuses.
The cause may be a blown in-line fuse behind the instrument panel (see Figure 12), which also controls voltage to terminal “E” at the transaxle.
Remove the glove compartment for access to the in-line fuses, and replace the A/C fuse (refer to Figure 12).
Some 1993-95 Cadillacs equipped with the THM 4T80-E transaxle may illuminate the Service Engine Soon lamp and store P080 as a current code. After you try to clear the code, it remains as a hard code.
This complaint occurs when the PCM has no throttle-position-sensor or idle-learn values stored and may be caused by one or more of the following:
- (1) A loss of power to the PCM, such as a prolonged battery disconnect
- (2) PCM replacement
- (3) High electrical loads such as headlamps, rear defogger, high HVAC blower operation or high-speed cooling-fan operation
- (4) Rough or unstable idle conditions.
Note:
If high electrical loads are the cause of this complaint, turn off the items mentioned in (3) and momentarily run the engine above 1,000 rpm to clear the high loads. Since cooling fans cannot be controlled manually, it will be necessary to have engine coolant temperature below 220° F (105° C) and A/C refrigerant temperature below 124° F (51° C).
If rough or unstable idle is the cause, this condition must be corrected before the relearn procedure is performed.
Important:
Because of engine-load differences with A/C on versus off, the idle relearn MUST be performed under both A/C on and off conditions!
A TP-sensor/idle-relearn procedure must be performed (see Figure 13). This will then allow you to clear the code and extinguish the Service Engine Soon light. If the relearn procedure has been successful, code P080 will become a historical code and then can be cleared.
If the code still remains current and the Service Engine Soon lamp is still illuminated after the relearn procedure has been performed, the following reasons may be at fault:
- (1) Throttle-position sensor
- (2) Throttle-position switch
- (3) Vehicle-speed sensor
- (4) Transaxle-range switch
- (5) Power-steering pressure switch
- (6) Brake switch
Important:
Before performing the relearn procedure make certain that:
- (1) Nothing is interfering with the accelerator or brake pedals.
- (2) The heated windshield is turned off.
- (3) There is no load on the power steering.
If these conditions are not met, the PCM will NOT be able to perform the relearn routine.
Before and/or after rebuild, the vehicle illuminates the Check Engine lamp and stores code P1887 or P0742 in memory. Once the code is stored, TCC will be inhibited and maximum line pressure will be set, creating harsh engagements and shifts.
- P1887 code definition: TCC release switch circuit malfunction.
- P0742 code definition: TCC locked on.
This usually is created by a leak of TCC release oil through the needle-bearing and seal assembly in the oil pump (see Figure 14).
This needle-bearing and seal assembly is now available under Transtar part number 67922B, which is a 2000 and later AX4N pump-bearing and seal assembly. The AX4N bearing is not available from Ford Motor Co. The bearing is also available from Sonnax under part number 33000-01. In some instances, because of the bearing failure, you will have to replace the entire pump assembly, which is available under OEM part number 24208987.
This needle-bearing and seal assembly has been such a high-failure item that ATSG recommends replacing it on every rebuild.
- Needle-bearing and seal assembly (Transtar Number) . . . . . . . .67922B
- Needle-bearing and seal assembly (Sonnax Number) . . . . . . . .33000-01
- Oil-pump assembly, complete . . . . . . . 24208987
December 2002 Issue
Volume 19, No. 12
- Volkswagen/Audi 01M: No Forward Engagement, or Slips on 1st-Gear Takeoff
- THM 4L80-E: New-Design Manual-2nd Band
- THM 4L80-E: Center-Gearbox Changes for 1999 Models
- THM 4T60-E: Third-Gear Starts, No A/C, No Voltage to “E” Terminal
- THM 4T80-E: Code P080 – TP-Sensor Idle Relearn Not Complete
- THM 4T40-E: Trouble Code P1887 or P0742