- At the start of production for the 1997 model year the input shaft has been redesigned in the area of the O-ring groove at the torque-converter end.
- After overhaul, vehicles equipped with the MP6 or MP7 transaxle may exhibit a complaint of falling out of Drive at a stop or a slipping condition on takeoff.
- Before or after overhaul, vehicles equipped with the MP6 or MP7 transaxle may exhibit a slight engagement delay in “D” and/or a binding condition in reverse.
- Before or after overhaul, vehicles equipped with the MP6 or MP7 transaxle may exhibit delayed or no reverse when hot.
- 1996-and-up vehicles equipped with the TAAT transaxle may exhibit harsh upshifts and/or down-shifts and may have diagnostic trouble code P0746 or P0789.
At the start of production for the 1997 model year the input shaft was redesigned in the area of the O-ring groove at the torque-converter end.
Elimination of the spiral ring.
The input shaft has three different configurations in the area of the O-ring groove at the converter end.
A) The first-design input shaft has an O-ring groove that is 0.189 inch in width and requires the spiral backup ring (refer to Figure 1).
B) The second-design input shaft has an O-ring groove that is 0.146 inch in width and has a machined surface that backs up the O-ring and eliminates the need for the spiral ring (refer to Figure 2).
C) The third-design input shaft has an O-ring groove that is 0.140 inch in width and does not need the spiral ring or the machined surface to back up the O-ring (refer to Figure 3).
Although all design levels of the O-ring area are interchangeable, attention must be given to the tooth count and width of the fourth drive gear, which is part of the input shaft.
- Spiral Backup Ring . . . . . . . . . . . . . . . .21002144
After overhaul, Saturn vehicles equipped with the MP6 or MP7 transaxle may exhibit a complaint of falling out of “Drive” at a stop or a slipping condition on takeoff.
The cause may be that during overhaul, the 2nd-, 3rd- or 4th-clutch return-spring assembly was mistakenly used in place of the 1st-clutch spring assembly. When this happens, the 1st clutch cannot fully engage until line pressure is increased. Refer to figures 4 and 5 to compare the 1st-clutch return-spring assembly with the 2nd-, 3rd- and 4th-clutch spring assemblies.
Notice that the coil diameter of the springs on 2nd, 3rd and 4th is about 0.010 inch larger and that those springs have an additional coil, which makes them stronger than the 1st-clutch springs.
Refer to Figure 4 to identify the 1st-clutch return-spring assembly and ensure that it is in the correct location.
Before or after overhaul, Saturn vehicles equipped with the MP6 or MP7 transaxle may exhibit a slight engagement delay in “D” and/or a binding condition in reverse.
The cause may be shrunken or damaged 1st-clutch sealing rings, as shown in Figure 6. When these rings leak they can cause a slow fill of the 1st clutch, which results in a delayed engagement in “D.” The first sealing ring also separates the 2nd clutch from the 1st clutch. When this ring leaks while in the Reverse range, the 1st clutch can now be applied with 2nd-clutch pressure, which results in a bind-up.
See Figure 7 for a cross-sectional view of the mainshaft.
Replace the 1st-clutch sealing rings as part of every overhaul.
Before or after overhaul, Saturn vehicles equipped with the MP6 or MP7 transaxle may exhibit a condition of delayed or no reverse when hot. This condition usually is accompanied by a soft or flared 2nd-gear upshift.
The cause may be a loose mainshaft nut, as shown in Figure 8, causing a leak in the 2nd-clutch circuit. When the nut loosens the mainshaft tends to walk back and forth in the mid case. This causes a gap between the 1st clutch and the nut, which is where the leak in the 2nd-clutch circuit appears.
In Figure 9 the cutaway shows how the 2nd clutch is fed around the outside of the feed pipe for the 3rd clutch. Notice that the areas over and under the nut are all part of the 2nd-clutch circuit.
Install a new mainshaft nut, which has a factory thread locker, as part of every repair. Using a 23mm 12-point socket, torque the new nut to 111 lb.-ft.
- Mainshaft nut . . . . .21001680
1996-and-up Saturn vehicles equipped with the TAAT transaxle may exhibit harsh upshifts and/or downshifts and may have a diagnostic trouble code P0746 (line-pressure-solenoid circuit open/grounded) or P0789 (solenoid intermittent circuit fault).
The cause may be a faulty line-pressure solenoid, poor connection at the main harness connector, poor contacts on the bus plate or a wiring problem leading to the PCM.
To correct this condition, refer to the following steps:
Remove the external harness connector and test resistance of the line-pressure solenoid across pins G and F of the bus plate, as shown in Figure 10.
If the resistance value is not within 4-6 ohms, replace the line-pressure solenoid in the location shown in Figure 11 and inspect the bus plate for burned terminals as shown in Figure 10. If the solenoid’s resistance is correct, go to Step 2.
Inspect the terminals inside the harness connector for a loose connection or burned terminals at G and F as shown in Figure 12. If the terminals are faulty, replace the harness connector with the repair harness. If the harness connector is good, go to Step 3.
Verify the integrity of the positive and ground sides of the line-pressure circuit from the underhood fuse block to the powertrain control module as shown in Figure 13. Repair harness as necessary. Note: The schematic shown is for a 2000 model; terminal locations at the PCM will vary by year model.
- 4th-design solenoid . . . . . . . . . . . . . . .21003344
- Bus plate . . . . . . . . . . . . . . . . . . . . . . .21002828
- Harness-connector repair kit . . . . . . . .21024415
April 2006 Issue
Volume 23, No. 4
- Input-Shaft Interchange
- Falls Out of Drive at a Stop
- Delay in ‘D’ and/or Bind in Reverse
- Delayed or No Reverse
- Harsh Shifts; Code P0746 or P0789