A/T - Shift Delay Before Warm Up
NO.: TSB-94-23-002DATE: May, 1994
MODEL: Various 1992-93 Models. See Below
SUBJECT:
A/T SHIFT DELAY BEFORE WARM-UP
BACKGROUND INFORMATION
Vehicles affected by an A/T shift delay exhibit the condition before reaching operating temperature. The shift delay described in this bulletin does not occur after normal vehicle operating temperature is reached. This bulletin is not intended to be used for any other transaxle condition except the "shift delay before warm-up."
Specific symptoms of the A/T shift delay include one or both of the following:
- Delayed shift engagement when moving the transmission shift selector between "Neutral" and "Drive," "Neutral" and "Reverse," "Park" and "Drive," or "Park" and "Reverse."
- Increased engine rpm ("Flair Shift") when the transmission shifts from "2nd" to "3rd."
These symptoms may originate from the transmission's Pressure Control Solenoid Valve (PCSV). The PCSV may not permit the correct flow of A/T fluid until the vehicle reaches operating temperature. After operating temperature is reached, the PCSV functions normally.
To correct the shift delay, it is necessary to replace the transmission's solenoid valve set. On the replacement valve set, the PCSV has been modified, permitting normal flow of A/T fluid at a wider range of operating temperatures.
The remainder of this bulletin describes affected vehicles, serial numbers of affected transaxles, how to diagnose the shift delay/flair shift condition, parts information (including lot number deciphering), and warranty information.
SERIAL NUMBERS OF AFFECTED TRANSAXLES
In addition to the VEHICLES AFFECTED information, transaxles exhibiting the shift delay can be identified by using the A/T serial number chart shown. The serial number is stamped into the top of the transaxle's case, near the bell housing.
DESCRIPTION
If a customer complains of an A/T shift delay before vehicle warm-up, perform the following procedure to verify and correct the condition. For accurate confirmation of the shift delay, it is necessary to test the vehicle when it is cold. Usually, this means keeping the vehicle over night. To minimize customer inconvenience, suggest that they drop their vehicle off the night before it is checked.
WARNING:
Observe standard shop safety practices while performing this procedure.
1. Connect the Scan Tool (MUT-II), turn the ignition key to the "ON" position (do not start the engine), and retrieve any stored Diagnostic Trouble Codes (DTCs). Do not disconnect the Scan Tool. It will be used again in Step 6.
2. Raise the vehicle on a suitable hoist and connect a 300 psi oil pressure gauge with adaptor to the kickdown (K/D) brake pressure "applied" port. Use part number MIT304253 for the gauge and part number MD998332-01 for the adaptor. These tools are part of your dealer's special service tool kit.
3. With the vehicle cold, start the engine, apply the foot brake, and shift the transmission between "N" and "D," "N" and "R," "P" and "D," and "P" and "R." If the transmission requires more than 1 second to shift into any of these modes, a shift delay may exist.
NOTE:
Do not run the engine for more than 30 seconds. Turn off the ignition immediately after completing Step 3. If the customer can leave their vehicle at the dealership for two days, go to Step 4. If the customer can only leave their vehicle at the dealership one day, go to Step 5.
4. To confirm the 2nd to 3rd flare shift, it is necessary to drive the vehicle when cold and listen for an rpm increase (or observe tachometer movement) when the transaxle shifts between the two gears.
NOTE:
This test will raise vehicle operating temperature above 30 degrees Celsius (86 degrees F), requiring the vehicle to be completely cold (8-12 hours of nonoperation) before proceeding to Step 5. While Step 4 is not required, it is very useful in making an accurate diagnosis of the shift delay.
5. Lower the vehicle to the ground, start the engine, and apply the parking brake and foot brake. Shift the transmission into "D" while keeping the engine at idle.
6. Using the Scan Tool in the "actuator" test mode, activate the PCSV for 5 seconds.
NOTE:
While the PCSV is activated, the K/D applied line pressure will raise and hold to 38 psi for about 2 seconds. During the next 3 seconds, the line pressure will fluctuate from 70 psi down to 40 psi, up to 130 psi, and finally down to about 20 psi.
At the completion of the 5 second test, if the oil pressure gauge reads less than 20 psi (138 kPa), the PCSV is not functioning normally and the A/T solenoid valve set should be replaced. For replacement information, refer to Section 23B or 23C of the 1992-94 Automatic Transmission Overhaul Manual.
If the oil pressure gauge reads more than 20 psi (138 kPa) after completing the 5 second test, the PSCV is functioning normally and the A/T solenoid valve set does not need to be replaced. Go to Step 7.
7. Using the DTCs retrieved in Step 1, perform additional troubleshooting measures to find the cause of the shift delay. For DTC information, refer to the appropriate vehicle's service manual. If no DTCs are found, ask the customer additional questions to determine if other abnormal transmission conditions are present.
PARTS INFORMATION
Replacement solenoid valve sets are available from your facing PDC. For specific part numbers, refer to Group 23 of the latest parts microfiche. Part numbers used for the new solenoid valve sets are unchanged from the old solenoid valve sets, however, all PDCs have been purged of the old stock.
Before installing the new solenoid valve set, be sure the new part has the correct lot number. The 4-digit lot number is stamped on top of one valve in the set. Refer to the illustration.
The new solenoid valve sets have lot numbers reading "3409" or higher. Here's how to decipher the lot number:
In the example "3409," "3" is the year (1993), "4" is the month (April), and "09" is the day Thus, parts manufactured on April 9, 1993 and later, are new.
Parts manufactured in October, November, and December use an alpha digit to indicate the month. For example, in the lot number 3XO9, "X" stands for October. In lot number 3Y09, "Y" stands for November. And, in lot number 3Z09, "Z" stands for December.
WARRANTY INFORMATION
Nature Code: 24B Position Code: 238601
Causal Code: 470 Coverage: Powertrain
Time Allowance: 0.3 (Inspection of symptoms and diagnosis with Scan Tool)
1.3 hrs (R&R solenoid valve set)