Circuit Description
The engine control module (ECM) uses the signals from the throttle position sensor, air-flow meter, turbine (input) speed sensor, intermediate (counter) shaft speed sensor and crankshaft position sensor to monitor the engagement condition of the lock-up clutch.
The ECM then compares the engagement condition of the lock-up clutch with the lock-up schedule in the ECM memory to detect a mechanical problems of the shift solenoid valve DSL, valve body and torque converter clutch.
Torque converter lock-up is controlled by the ECM based on the speed sensor (NT), speed sensor (NC), engine rpm, engine load, engine temperature, vehicle speed, transmission temperature, and gear selection. The ECM determines the lock-up status of the torque converter by comparing the engine rpm (NE) to the input turbine rpm (NT). The ECM calculates the actual transmission gear by comparing input turbine rpm (NT) to counter gear rpm (NC). When conditions are appropriate, the ECM request "lock-up" by applying control voltage to the shift solenoid DSL. When the shift solenoid DSL is turned on, it applies pressure to the lock-up relay valve and locks the torque converter clutch.
If the ECM detects no lock-up after lock-up has been requested or if it detects lock-up when it is not requested, the ECM interprets this as a fault in the shift solenoid valve DSL or lock-up system performance. The ECM will illuminate the MIL and store the DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0741 Torque Converter Clutch Solenoid Performance (Shift Solenoid Valve DSL)
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
| • | Lock-up does not occur when driving in lock-up range. |
| • | Lock-up remains ON in lock-up OFF range |
| • | Engine speed is at least 100 rpm greater than input turbine speed. |
| • | The difference between engine speed and input turbine speed is less than 35 rpm. |
Action Taken When the DTC Sets
| • | DTC P0741 is a type C DTC. |
| • | The malfunction indicator lamp (MIL) illuminates the first time the diagnostic runs with the fault active. |
Conditions for Clearing the MIL/DTC
The DTC will clear when conditions for setting the DTC have been repaired.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Automatic Transmission Controls Schematics Connector End View Reference: Component Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Does the engine speed change? | -- | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections |
3 |
Is the resistance measured within specified value? | 11 to 13 Ohms | Go to Step 4 | Go to Step 5 |
4 |
Is the resistance measured within specified value? | 11 to 13 Ohms | Go to Step 5 | Go to Step 9 |
5 |
Is the resistance measured within the specified range and can an operating sound be heard when connecting the positive and negative leads. | 11 to 13 Ohms | Go to Step 6 | Go to Step 11 |
6 | Inspect shift solenoid valve DSL circuit for an open or short on the wire harness. Is circuit OK? | -- | Go to Step 7 | Go to Step 10 |
7 | Inspect transmission valve body assembly for foreign objects and each valve operates smoothly. Is transmission valve body operation OK? | -- | Go to Step 8 | Go to Step 12 |
8 | Inspect torque converter clutch assembly for normal operation. Is torque converter clutch operation OK? | -- | Go to Step 14 | Go to Step 13 |
9 | Repair or replace harness or connector of the ECM. Refer to Wiring Repairs and Connector Repairs . Did you complete the repair or replacement? | -- | Go to Step 14 | -- |
10 | Repair or replace harness or connector of the shift solenoid valve DSL. Refer to Wiring Repairs and Connector Repairs . Did you complete the repair or replacement? | -- | Go to Step 14 | -- |
11 | Replace the shift solenoid valve DSL. Did you complete the replacement? | -- | Go to Step 14 | -- |
12 | Replace the transmission valve body assembly. Did you complete the replacement? | -- | Go to Step 14 | -- |
13 | Replace the torque converter clutch assembly. Did you complete the replacement? | -- | Go to Step 14 | -- |
14 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
