Circuit Description
The torque converter clutch (TCC) solenoid valve is an ON/OFF (normally OFF) valve which controls the converter clutch apply and release. The torque converter clutch pulse width modulation (TCC PWM) solenoid valve works with the TCC solenoid valve to control the clutch apply rate (feel). The PCM controls the duty cycle on the TCC PWM solenoid valve to regulate the feed pressure to the converter clutch regulator valve, which in turn, regulates the converter clutch apply pressure.
The TCC solenoid valve receives ignition voltage from circuit 1039. The PCM controls the ground path on circuit 422 to turn the solenoid on and off. The PCM uses throttle position, vehicle speed and other inputs in order to determine when to energize the solenoid. When the solenoid is OFF, the PCM will receive a high (ignition voltage) signal. When the solenoid is ON, the PCM will receive a zero voltage signal.
When the PCM detects a continuous open or short in the TCC solenoid valve circuit, then DTC P0740 sets. DTC P0740 is a type B DTC.
Conditions for Running the DTC
| • | System voltage is 10-18 volts. |
| • | The engine speed is greater than 500 RPM for 5 seconds. |
| • | Not in fuel shut off. |
Conditions for Setting the DTC
DTC P0740 sets if one of the following conditions exists for 5 seconds:
Condition 1
The PCM commands the solenoid ON, and the voltage signal to the PCM remains high (B+).
Condition 2
The PCM commands the solenoid OFF, and the voltage signal to the PCM remains low (0 volts).
Action Taken When the DTC Sets
| • | The PCM inhibits TCC. |
| • | The PCM inhibits 4th gear, if the transmission is in hot mode. |
| • | The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutve trip in which the conditions for setting the DTC are met. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes. |
| • | A scan tool clears the DTC from PCM history. |
| • | The PCM clears the DTC from the PCM history if the vehicle completes 40 consecutive warm-up cycles without an emission related diagnostic fault occurring. |
| • | The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM. |
Diagnostic Aids
| • | Inspect the wiring at the PCM, the transmission connector, TCC enable solenoid connector and all other circuit connecting points for the following conditions: |
| - | A backed out terminal |
| - | A damaged terminal |
| - | Reduced terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation |
| - | Moisture intrusion |
| - | Corrosion |
| • | When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the test equipment for a change. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step isolates the fault between the engine harness and the transmission harness.
-
This step checks if engine harness circuit 422 is open.
-
This step checks if the solenoid and transmission wiring is within resistance specifications.
Step | Action | Value(s) | Yes | No | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||||||||||||
2 |
Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from the PCM. Were DTCs P0753, P0758 or P1860 set also? | -- | ||||||||||||||||
3 | Remove the Trans fuse. Inspect the fuse for an open. Refer to Wiring Repairs in Wiring Systems. Was a condition found and corrected? | -- | ||||||||||||||||
4 | Inspect for a short to ground in engine harness circuit 1039 (PNK) or transmission harness circuit 839 (RED). Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found? | -- | -- | |||||||||||||||
5 | Inspect for an open in engine harness circuit 1039 (PNK) or transmission harness circuit 839 (RED). Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found? | -- | -- | |||||||||||||||
Is the test lamp on? | -- | |||||||||||||||||
7 | Repair the open in ignition feed circuit 1039 (PNK) to the transmission connector. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |||||||||||||||
Does the test lamp turn ON and OFF? | -- | |||||||||||||||||
9 | Inspect circuit 422 (TAN/BLK) of the engine wiring harness for an open, short to ground or short to power. Refer to General Electrical Diagnosis in Wiring Systems. Did you find an open or short condition? | -- | ||||||||||||||||
10 |
Is the measured resistance within the specified range? | 19-24 ohms @ 20°C (68°F) 24-31 ohms @ 88°C (190°F) | ||||||||||||||||
Connect DMM from jumper terminal D to A, B, C, F and the transmission case. Are all resistances greater than the specified value | 100 ohms | |||||||||||||||||
12 | Is the resistance greater than the specified value? | 31 ohms | ||||||||||||||||
13 | Inspect the transmission harness circuit 839 (RED) and circuit 422 (TAN) for an open. Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found? | -- | ||||||||||||||||
14 | Disconnect wiring harness from the TCC solenoid. Connect DMM from jumper terminal D to terminal E. Is resistance greater than the specified value? | 100 ohms | ||||||||||||||||
15 | Replace the automatic transmission wiring harness. Refer to Solenoids and Wiring Harness Replacement . Is the replacement complete? | -- | -- | |||||||||||||||
16 | Replace the TCC solenoid valve. Refer to Torque Converter Clutch Solenoid Replacement . Is the replacement complete? | -- | -- | |||||||||||||||
17 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls. Is the replacement complete? | -- | -- | |||||||||||||||
18 | Repair the wiring as needed. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |||||||||||||||
19 | Perform the following in order to verify the repair:
Has the test run and passed? | -- | System OK |
