Circuit Description
The powertrain control module (PCM) uses signals from the vehicle speed sensor to detect torque converter clutch (TCC) lock-up status. The PCM then compares the actual data with the TCC lock-up schedule in the PCM memory to detect mechanical trouble of the TCC solenoid and valve body.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0770 Torque Converter Clutch (TCC) System Performance
Conditions for Setting the DTC
DTC P0770 will set when one of the following conditions are met:
| • | TCC lock-up does not occur after the PCM commands the TCC to apply. |
| • | TCC remains locked-up even after the PCM commands the TCC to release. |
Action Taken When the DTC Sets
A DTC P0770 is stored and the malfunction indicator lamp (MIL) is turned ON.
Diagnostic Aids
Inspect for the following conditions:
| • | Clogged or leaky TCC solenoid |
| • | Valve body fluid passage clogged |
| • | Torque converter clutch malfunction |
| • | Faulty PCM |
If this DTC cannot be duplicated, the information included in the freeze frame data can be useful in determining vehicle operating conditions when the DTC was first set.
DTC Confirmation Procedure
- Turn the ignition switch to LOCK.
- Connect the scan tool to data link connector (DLC).
- Turn the ignition switch to ON.
- Clear the DTC, the pending DTC, and the freeze frame data in PCM memory by using the scan tool.
- Start the engine and warm up to normal operating temperature.
- Use the scan tool to monitor the operation of the TCC solenoid.
- Accelerate vehicle in Drive (D) range and drive at 80 km/h (50 mph) for 10 seconds.
- Stop the vehicle.
- Test for a pending DTC with the scan tool.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The Diagnostic System Check - Vehicle, prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
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This step checks for proper shift points.
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This step checks for a stuck closed lock-up solenoid.
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This step checks for a leaky lock-up solenoid.
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This step checks the condition of the valve body assembly.
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This step checks for a faulty PCM.
Step | Action | Yes | No |
|---|---|---|---|
Did you preform the Diagnostic System Check - Vehicle? | Go to Step 2 | ||
2 | Does the scan tool display any other DTCs? | Go to applicable DTC table | Go to Step 3 |
3 |
Did DTC P0770 reset? | Go to Step 4 | Go to Diagnostic Aids |
Perform the Upshifts and Torque Converter Clutch Apply Procedure in Road Test in order to diagnose the mechanical condition of the transaxle. Was a mechanical failure detected? | Go to Step 11 | Go to Step 5 | |
Did the lock-up solenoid outlet port open and did air escape? | Go to Step 10 | Go to Step 6 | |
Did the lock-up solenoid outlet port stay closed and did no air leak? | Go to Step 10 | Go to Step 7 | |
Remove valve body and inspect its passages for any obstructions/restrictions. Refer to Solenoids and Wiring Harness Replacement . Is the valve body in good condition? | Go to Step 8 | Go to Step 9 | |
Does this DTC reset? | Go to Step 11 | Go to Step 12 | |
9 | Repair or overhaul valve body assembly. Is the action complete? | Go to Step 13 | -- |
10 | Replace the lock-up solenoid. Is the action complete? | Go to Step 13 | -- |
11 | Refer to Road Test for further diagnosis of the transaxle performance. Repair as necessary. Is the action complete? | Go to Step 13 | -- |
12 | Replace PCM. Refer to Powertrain Control Module Programming and Setup. Is the action complete? | Go to Step 13 | -- |
13 | Observe the Capture Info with the scan tool. Are there any DTCs that have not been diagnosed? | System OK |
