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P0743






P0743-TCC SOLENOID CIRCUIT





For a complete wiring diagram Refer to the Wiring Information

Theory of Operation

The TCC Solenoid is activated when the Transmission Control Module (TCM) determines that the Torque Converter Clutch should be activated. The Torque Converter Clutch is a variable slip torque clutch that allows control of the slip from 5.5% to 95.5% of lock-up. The Clutch is controlled by the TCC Solenoid which is pulse width modulated (PWM) to provide the desired amount of slip. The clutch requires both an electrical PWM of 1000Hz and an hydraulic PWM of 100Hz.

- When Monitored:
Continuously with the ignition on, engine running, with the transmission in gear, the TCC Solenoid is inactive, or when the TCC Solenoid is active and controlled above 25% duty cycle, with the Solenoid Supply voltage active.

- Set Condition:
If the TCM detects on the TCC Solenoid control circuit: open, short to ground, short to voltage, internal short in the TCC Solenoid or an open in the TCC Solenoid.





Always perform the NAG1 Pre-Diagnostic Troubleshooting procedure before proceeding. NAG1 Pre-Diagnostic Troubleshooting Procedure

1. CHECK IF THE DTC IS CURRENT

NOTE: If the TCM detects and stores a DTC, the TCM also stores the vehicles operating conditions under which the DTC originally set. This information is located in scan tool under Environmental Data. Before erasing any stored DTCs, record any available data to assist in duplicating the conditions in which the DTC originally set.

1. Turn the ignition off to the lock position.
2. With the scan tool, erase Transmission DTC's.
3. Using the Environmental Data recorded earlier, try to duplicate the conditions in which the DTC originally set. It may be necessary to test drive the vehicle.
4. With the scan tool, read Transmission DTC's.

Did the DTC P0743 reset?

Yes

- Go To 2

No

- Go To 6

2. CHECK THE (T75) TCC SOLENOID CONTROL CIRCUIT FOR AN OPEN




1. Turn the ignition off to the lock position.
2. Disconnect the TCM C2 harness connector.
3. Disconnect the Transmission Electrohydraulic Control Unit Assembly harness connector.

NOTE: Check connectors - Clean/repair as necessary.

4. Measure the resistance of the (T75) TCC Solenoid Control circuit from the TCM C2 harness connector to the Transmission Electrohydraulic Control Unit Assembly harness connector.

Is the resistance above 5.0 ohms?

Yes

- Repair the (T75) TCC Solenoid Control circuit for an open.
- Perform NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test

No

- Go To 3

3. CHECK THE (T75) TCC SOLENOID CONTROL CIRCUIT FOR A SHORT TO GROUND




1. Measure the resistance between ground and the (T75) TCC Solenoid Control circuit.

Is the resistance below 5.0 ohms?

Yes

- Repair the (T75) TCC Solenoid Control circuit for a short to ground.
- Perform NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test

No

- Go To 4

4. CHECK THE (T75) TCC SOLENOID CONTROL CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT




1. Measure the resistance between the (T75) TCC Solenoid Control circuit and all other circuits in the Transmission Electrohydraulic Control Unit Assembly harness connector.

Is the resistance below 5.0 ohms between the (T75) TCC Solenoid Control circuit and any other circuit(s) in the Transmission Electrohydraulic Control Unit Assembly harness connector?

Yes

- Repair the (T75) TCC Solenoid Control circuit for a short to another circuit.
- Perform NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test

No

- Go To 5

5. CHECK THE TCC SOLENOID RESISTANCE




1. Reconnect the Transmission Electrohydraulic Control Unit Assembly harness connector.
2. Measure the resistance of the TCC Solenoid between the (T75) TCC Solenoid Control circuit and the (T78) Solenoid Supply circuit in the TCM C2 harness connector.

Is the resistance of the TCC Solenoid between 2.0 and 4.0 ohms?

Yes

- Using the schematics as a guide, check the Transmission Control Module (TCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the TCM. Transmission Control Module - Description
- Perform NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test

No

- Replace the TCC Solenoid. Electrohydraulic Control Unit - Disassembly
- Perform NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test

6. INTERMITTENT WIRING AND CONNECTORS
1. The conditions necessary to set this DTC are not present at this time.
2. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
3. Wiggle the wiring and connectors while checking for any possible open or shorted circuits.
4. Check for any Service Information Tune-ups or Technical Service Bulletins that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test

No

- Test Complete.

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