For 1990-2009 cars

## DTC P1792 Non European Emissions

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P1792 Engine Coolant Signal

### Conditions for Setting the DTC

• | Transmission control module (TCM) detects no engine coolant temperature (ECT) signal for 2 seconds continuously

• | No DTC U2105

• | TCM judges the ECT is 90°C (194°F) when lapse 15 minutes from ignition ON

### Action Taken When the DTC Sets

The TCM will not request the illumination of the malfunction indicator lamp (MIL) or hold lamp, but will store the DTC when the TCM detects a failure on the 1st ignition cycle

### Conditions for Clearing the DTC

• | The scan tool can clear the DTC from the TCM history.

• | The TCM clears the DTC from the TCM history memory after 40 consecutive ignition cycles without fault.

### Cause of Failure

• | Wiring harness or connector between engine control module (ECM) and TCM

• | ECM

• | TCM

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 |

1. Turn OFF the ignition.
2. Install the scan tool.
3. Turn ON the ignition, with the engine OFF.
4. Select Clear DTC Information from the Diagnostic Trouble Codes Information menu.
5. Clear DTC Information.
6. Perform 1 vehicle drive cycle.
7. Select Request DTC by Status from the Diagnostic Trouble Codes Information menu.
8. Request DTC by Status.

Is DTC P1792 displayed?

--

Go to Step 2

Go to Step 7

2 |

1. Turn OFF the ignition.
2. Disconnect the transmission control module (TCM) wiring connector and engine control module (ECM) wiring connector.
3. Measure the resistance between terminal A17 of the TCM wiring connector and terminal 88 of the ECM wiring connector.
4. Measure the resistance between terminal A7 of the TCM wiring connector and terminal 57 of the ECM wiring connector.

Is the resistance within the specified value?

0 ohms

Go to Step 3

Go to Step 4

3 |

1. Turn ON the ignition, with the engine OFF.
2. Measure the voltage of terminal A17.
3. Measure the voltage of terminal A7.

Is the voltage within the specified range?

11-14 V

Go to Step 4

Go to Step 5

4 | Repair the malfunctioning terminals as necessary. Did you complete the repair? | -- | System OK | --
5 |

1. Replace the TCM. Refer to Transmission Control Module Replacement .
2. Turn OFF the ignition.
3. Turn ON the ignition.
4. Inspect for DTC P1792.

Is the DTC set?

--

Go to Step 6

Go to Step 8

6 | Replace the ECM. Refer to Engine Control Module Replacement for the 1.8L (L79) engine or Engine Control Module Replacement for the 2.0L (L34 GMDAT) engine. Did you complete the replacement? | -- | Go to Step 8 | --
7 | Repair the temporary connection of the connector. Refer to Wiring Harness and Connector Inspection Diagnosis . Did you complete the repair? | -- | System OK | --
8 |

1. After the repair, use a scan tool clear info function and road test the vehicle.
2. Review the DTC info.

Has the last test failed or is the current DTC displayed?

--

Go to Step 1

System OK

## DTC P1792 European Emissions

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P1792 Engine Coolant Signal

### Conditions for Setting the DTC

• | Transmission control module (TCM) detects no engine coolant temperature (ECT) signal for 2 seconds continuously

• | No DTC U2105

• | TCM judges the ECT is 90°C (194°F) when lapse 15 minutes from ignition ON

### Action Taken When the DTC Sets

The TCM will not request the illumination of the malfunction indicator lamp (MIL), but will store the DTC when the TCM detects a failure on the 1st ignition cycle

### Conditions for Clearing the DTC

• | The scan tool can clear the DTC from the TCM history.

• | The TCM clears the DTC from the TCM history memory after 40 consecutive ignition cycles without fault.

### Cause of Failure

• | Wiring harness or connector between engine control module (ECM) and TCM

• | ECM

• | TCM

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 |

1. Turn OFF the ignition.
2. Install the scan tool.
3. Turn ON the ignition, with the engine OFF.
4. Select Clear DTC Information from the Diagnostic Trouble Codes Information menu.
5. Clear DTC Information.
6. Perform 1 vehicle drive cycle.
7. Select Request DTC by Status from the Diagnostic Trouble Codes Information menu.
8. Request DTC by Status.

Is DTC P1701 or P1792 displayed?

--

Go to Step 2

Go to Step 7

2 |

1. Turn OFF the ignition.
2. Disconnect the transmission control module (TCM) wiring connector and engine control module (ECM) wiring connector.
3. Measure the resistance between terminal A17 of the TCM wiring connector and terminal 88 of the ECM wiring connector.
4. Measure the resistance between terminal A7 of the TCM wiring connector and terminal 57 of the ECM wiring connector.

Is the resistance within the specified value?

0 ohms

Go to Step 3

Go to Step 4

3 |

1. Turn ON the ignition, with the engine OFF.
2. Measure the voltage of terminal A17.
3. Measure the voltage of terminal A7.

Is the voltage within the specified range?

11-14 V

Go to Step 4

Go to Step 5

4 | Repair the malfunctioning terminals as necessary. Did you complete the repair? | -- | System OK | --
5 |

1. Replace the TCM. Refer to Transmission Control Module Replacement .
2. Turn OFF the ignition.
3. Turn ON the ignition.
4. Inspect for DTC P1792.

Is the DTC set?

--

Go to Step 6

Go to Step 8

6 | Replace the ECM. Refer to Engine Control Module Replacement for the 1.8L (L79) engine or Engine Control Module Replacement for the 2.0L (L34 GMDAT) engine. Did you complete the replacement? | -- | Go to Step 8 | --
7 | Repair the temporary connection of the connector. Refer to Wiring Harness and Connector Inspection Diagnosis . Did you complete the repair? | -- | System OK | --
8 |

1. After the repair, use a scan tool clear info function and road test the vehicle.
2. Review the DTC info.

Has the last test failed or is the current DTC displayed?

--

Go to Step 1

System OK