For 1990-2009 cars
Automatic Transmission Components
Automatic Transmission Controls Schematics
OBD II Symbol Description Notice

### Circuit Description

The Torque Converter Clutch (TCC) solenoid is located in the transmission adapter case. The solenoid valve controls the engagement and disengagement of the torque converter clutch in 3rd and 4th gears. The TCC operation is dependent on transmission fluid temperature, brake switch state, selected program, vehicle speed, etc. The TCM controls the TCC solenoid and the solenoid controls transmission fluid flow to the TCC.

The TCC solenoid is supplied power via the Transmission Power Relay (internal to the TCM). The TCM controls the solenoid by grounding the control circuit via an internal solid state device called a driver. The primary function of the driver is to supply the ground for the controlled component. Each driver has a fault line which is monitored by the TCM. When the TCM is commanding a component on, the voltage of the control circuit should be low (near 0 volts). When the TCM is commanding the control circuit to a component off, the voltage potential of the circuit should be high (near the battery voltage). If the fault detection circuit senses a voltage other than what you expect, this DTC will set.

### Conditions For Running The DTC

Tests continuously

### Conditions for Setting the DTC

A short to ground, open circuit, or short to battery voltage detected on the control circuit.

### Action Taken When the DTC Sets

• | The TCM illuminates the Service Transmission Lamp (STL) and sends a MIL Request to the ECM on the second consecutive drive trip that the diagnostic runs and fails. The ECM then illuminates the MIL.

• | The ECM records the operating conditions in the Freeze Frame at the time of the MIL Request from the TCM.

• | The transmission operates in the Default Mode.

### Conditions for Clearing the MIL/DTC

• | The TCM turns off the STL as soon as the fault is no longer present.

• | The ECM turns off the MIL after three consecutive drive trips during which the TCM sends no MIL Request.

• | A History DTC clears after forty consecutive warm-up cycles, if no failures are present by this diagnostic or any other emission related diagnostic.

• | The scan tool clears the MIL/DTC.

### Diagnostic Aids

Use the Connector Test Adapter Kit J 35616-A for any test that requires probing the TCM harness connector or a component harness connector. Using this kit will prevent damage to the harness connector terminals.

Check for the following conditions:

• | Poor connections at the TCM or at the component. Inspect the harness connectors for any backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. Refer to Engine Electrical, Troubleshooting Procedures, Checking Terminal Contact for proper procedure.

• | Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the scan tool while moving any related connectors and any wiring harnesses. A change in the display may help to locate the fault.

### Test Description

The number(s) below refer to the step numbers on the diagnostic table.

1. Lets the TCM determine if the fault is present now.

2. Listen for an audible click when the solenoid operates. Ground the circuit repeatedly if necessary.

3. This check can detect a partially shorted coil which would cause an excessive current flow. Leaving the circuit energized for 2 minutes allows the coil to warm up. When the coil warms up, the coil may open (Amps drop to 0), or short (goes above 0.75 Amp).

4. Be sure to probe the correct Transmission Power Relay output circuit (there are two in the adapter case harness). Pins 54 and 40 are connected within the TCM.

5. If the solenoid checks out OK and no trouble is found with the connections at the TCM, check the wiring and connections closely. If no trouble is found, the TCM may be the cause of the problem; however this would be an extremely unlikely failure.

#### DTC P0743 - Torque Converter Clutch (TCC) Solenoid Control Circuit

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Review the Freeze Frame data for this DTC and observe the parameters with the ignition ON and with the engine off.
2. Clear the DTCs.
3. Turn off the ignition for 15 seconds.
4. Start the engine.
5. Operate the vehicle within the conditions required for this diagnostic to run, and as close to the conditions recorded in Freeze Frame as possible. Refer to Conditions for Running the DTC.
6. Check for any DTCs.

Is DTC P0743 set?

--

Go to Step 3

No trouble found

Refer to Diagnostic Aids

3 |

1. Turn off the ignition.
2. Disconnect the TCM.
3. Use a fused jumper in order to jumper the Transmission Power Relay output circuit (terminal 54) in the TCM harness connector to B+.
4. Probe the solenoid control circuit in the TCM harness connector with a fused jumper wire connected to ground.

Does the solenoid operate?

--

Go to Step 4

Go to Step 5

4 | Measure current from the solenoid control circuit in the TCM harness connector to ground for 2 minutes with a DVM J 39200 on a 10 Amp scale. Does the current draw a measure within the range shown? | 0.4 to 0.75A | Go to Step 16 | Go to Step 15
5 |

1. Leave the Transmission Power Relay output circuit jumpered to B+.
2. Disconnect any other jumpers.
3. Disconnect the transmission adapter case harness connector.
4. With the test light connected to ground, probe the Transmission Power Relay output circuit in the harness connector.

Does the test light illuminate?

--

Go to Step 6

Go to Step 13

6 | With the test light connected to ground, probe the solenoid control circuit in the harness connector. Does the test light illuminate? | -- | Go to Step 10 | Go to Step 7
7 | Connect the test light between the Transmission Power Relay output circuit and the solenoid control circuit at the transmission adapter case harness connector. Does the test light illuminate? | -- | Go to Step 11 | Go to Step 8
8 | With the test light still connected, jumper the solenoid control circuit to ground at the TCM harness connector. Does the test light illuminate? | -- | Go to Step 9 | Go to Step 12
9 | Check the transmission harness connector for a poor connection or poor terminal tension. Refer to Engine Electrical, Troubleshooting Procedures, Checking Terminal Contact for proper procedure. Was a problem found and corrected? | -- | Go to Step 17 | Go to Step 14
10 | Repair the solenoid control circuit shorted to B+. Is the action complete? | -- | Go to Step 17 | --
11 | Repair the solenoid control circuit shorted to ground. Is the action complete? | -- | Go to Step 17 | --
12 | Repair the open/high resistance solenoid control circuit. Is the action complete? | -- | Go to Step 17 | --
13 | Repair the Transmission Power Relay output circuit to the solenoid. Is the action complete? | -- | Go to Step 17 | --
14 | Check the internal transmission harness to the solenoid for the following conditions:

• | pen Circuit

• | Short to ground

• | Short to B+

• | Poor connections/terminal tension. Refer to Engine Electrical, Troubleshooting Procedures, Checking Terminal Contact for proper procedure.

Was a problem found and corrected?

--

Go to Step 17

Go to Step 15

15 | Replace the solenoid. Is the action complete? | -- | Go to Step 17 | --
16 | Check the TCM harness connector for a poor connection or poor terminal tension. Refer to Engine Electrical, Troubleshooting Procedures, Checking Terminal Contact for proper procedure. Was a problem found and corrected? | -- | Go to Step 17 | Go to Test Description
17 |

1. Clear the DTCs with the scan tool.
2. Turn off the ignition for 15 seconds.
3. Start the engine.
4. Operate the vehicle within the conditions required for this diagnostic to run. Refer to Conditions for Running the DTC.
5. Check for any DTCs.

Is DTC P0743 set?

--

Go to Step 2

Go to Step 18

18 | Were there any additional DTCs noted during the Powertrain or Transmission OBD System Check that have not been diagnosed? | -- | Go to the applicable DTC table | Go to Step 19
19 | Does the Transmission now function properly? | -- | System OK | Go to Functional Test