A/T - Delayed Engagement Diagnostic Procedure
NO.: TSB-98-23-015DATE: October, 1998
MODEL: 1995-98 Eclipse
SUBJECT:
DELAYED TRANSAXLE ENGAGEMENT
PURPOSE
Automatic transaxle engagement is considered to be delayed if it takes longer than three seconds to shift into gear. This bulletin contains diagnosis and repair information for affected vehicles experiencing intermittent delayed transaxle engagement.
NOTE:
Delayed transaxle engagement after the vehicle has been parked for several days is considered normal Warming up the vehicle in Neutral should speed-up engagement.
AFFECTED VEHICLES
1995-98 Eclipse models equipped with 2.0L non-turbocharged engine and automatic transaxle
DIAGNOSIS
Before performing any transaxle service, first verify that the TCU has the latest software level, using Reprogramming Unit MIT992000. Refer to TSB-95-23-002 (1995 models), TSB-98-23-003 (1996-97 models), or TSB-98-23-002 (1998 models) for the latest TCU reprogramming cartridge.
1. Check the transaxle fluid level.
2. Connect the MUT-II scan tool.
3. Using the MUT-II, check for any diagnostic trouble codes (DTCs). Also check Scan Tool Data List item # 46, "Shift & Limp-In" to verify that the appropriate gear is displayed on the MUT-II screen as the shift lever is moved.
a. If no problem is found and no DTCs are set, go to Step 4.
b. If any problem is found, repair as necessary, then go to Step 4.
c. If DTC 28 ("Check Shifter Signal") is set, refer to page 23A-138 in the 1998 Eclipse service manual for troubleshooting procedures. Repair as necessary, then continue with Step 4.
d. If any powertrain control module DTCs are set, refer to the appropriate DTC troubleshooting procedures in Group 13 of the Eclipse service manual. Repair as necessary, then go to Step 4.
4. Follow the troubleshooting chart in this bulletin. The charts refer to the repair procedures on pages 3 through 5. Depending on the results of Step 3, you may need to follow more than one chart.
DELAYED TRANSAXLE ENGAGEMENT - F4AC1 A/T
IMPORTANT:
Be sure that Steps 1 through 3 are completed before continuing with the troubleshooting flowcharts.
REPAIRS
DTC 35 "Check ATF Level" (1995-98 Models)
If any other DTC is also set, troubleshoot the other DTC first. Refer to the appropriate DTC troubleshooting procedure in the service manual.
NOTE:
If DTC 35 is set during ATF change, it is an erroneous code.
1. If the ATF level was not correct in Step 1 on page 1 of this bulletin, and ATF was added, erase the DTC at this time. Then road test the vehicle to verify that the DTC does not reset.
a. If DTC 35 resets, replace the A/T oil pump.
b. If DTC 35 does not reset, go to Step 2 below.
2. Verify that the A/T filter is not damaged and properly installed.
3. If no problems are found with the ATF level or the A/T filter, replace the A/T oil pump.
Low-Reverse Inner and Outer Seals (1995-96 Models)
Seals are critical to transaxle performance. Inspect the lip of the seal to confirm it is not bent over or has not taken a set. It should be rounded and not flattened. Remove the seal, then place it back into position to see if it fits loosely. If so, it must be replaced.
You can perform a pressure check during a cold start to determine whether the seals have taken a set. The Low-Reverse, Underdrive and/or Reverse pressures will be slow to engage only once during the cold start (vehicle must sit until cold to test again).
Leaking Low-Reverse inner and outer seals can cause DTC 36 ("Fault Immediately After a Shift") to set along with DTC 50 or 51 ("Gear/Speed Ratio Error"). Typically, the customer will complain of "shift bump" (rough shift into first gear as the vehicle comes to a stop) before experiencing delayed engagement. (If overhauling the transaxle for extensive repairs, replace all clutch seals and the Low-Reverse piston retainer.)
Low-Reverse inner and outer seals made of improved material have been installed on transaxles built after 11/16/95 (transaxle identification number xxxx-2529-xxxx and higher). The improved seals are available as repair parts, and are listed in the PARTS INFORMATION section of this bulletin.
Check Ball Clearance (1995 Models only)
If the check ball indicated in the illustration below does not have the proper clearance, it may slick in position when the transaxle is hot. This condition can cause delayed engagement.
1. When the transaxle is cold, remove the valve body.
2. Using a dial caliper, measure the distance between the top of the check ball and the valve body top edge (machined surface).
3. If the measurement is less than 0.178 mm (0.007 in.), replace the valve body.
Park/Neutral Position Switch (1995 Models only)
In below freezing ambient temperatures, moisture may collect in the Park/Neutral switch and freeze. When this occurs, the transaxle may experience a delay when shifting into Reverse gear and DTC 24 may set. This may occur intermittently, since as the transaxle warms the condition is automatically corrected.
To eliminate the shift delay, replace the Park/Neutral switch.
Output Speed Sensor (1996-98 Models Only)
The transaxle temperature sensor uses the same ground circuit as the speed sensor. If the output speed sensor reading is greater than 0 rpm, electrical noise may be induced into the harness wires from the input or output speed sensors to the TCM. The "reverse block" logic in the TCM prevents the vehicle from shifting into Reverse if it senses that the vehicle is moving over 8 mph.
Intermittent electrical noise may cause reverse block logic to be activated. If the output speed sensor reading during a Park to Reverse shift is over 400 rpm, "reverse block" logic is activated.
^ If the electrical noise is continuous, this condition will remain until the problem is repaired.
^ If the electrical noise is intermittent, the output speed sensor reading may be fixed above 400 rpm. This prevents a shift to Reverse until the shifter is moved into a forward gear, then back into Reverse.
1. Place the transaxle in Park. Start the engine and allow to idle.
2. Connect the MUT-II scan tool and check the output speed sensor reading. If the output speed sensor reading is greater than 0 rpm, go to Step 3.
3. There may be corrosion or other damage to the speed sensor wiring harness or related splices and grounds. Follow the troubleshooting procedures for DTC 56 ("Speeds error: Input Speed Sensor") and DTC 57 ("Speeds error: Output Speed Sensor") in Group 23 of the appropriate service manual.
PARTS INFORMATION
WARRANTY INFORMATION
Normal warranty procedures apply.