For 1990-2009 cars

### Circuit Description

The throttle actuator control (TAC) system uses an ignition voltage supply separate from the powertrain control module (PCM) supply. If the PCM detects a voltage difference between the 2 circuits, this diagnostic trouble code (DTC) will set.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P1682 Ignition 1 Switch Circuit 2

### Conditions for Running the DTC

The ignition is ON.

### Conditions for Setting the DTC

• | The TAC voltage is not in range.

• | The condition exists for more than 10 seconds.

### Action Taken When the DTC Sets

• | The control module stores the DTC information into memory when the diagnostic runs and fails.

• | The malfunction indicator lamp (MIL) will not illuminate.

• | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.

• | The driver information center, if equipped, may display a message.

### Conditions for Clearing the DTC

• | A current DTC Last Test Failed clears when the diagnostic runs and passes.

• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.

• | Clear the DTC with a scan tool.

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Observe the Freeze Frame/Failure Records for this DTC.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Does the DTC fail this ignition?

Go to Step 3

Go to Intermittent Conditions

3 |

1. Turn ON the ignition, with the engine OFF.
2. With a test lamp connected to ground, probe both sides of the ETC fuse.

Does the test lamp illuminate on both sides of the fuse?

Go to Step 5

Go to Step 4

4 | Does the test lamp illuminate on one side of the fuse? | Go to Step 7 | Go to Powertrain Relay Diagnosis
5 |

1. Turn OFF the ignition for 15 seconds.
2. With a test lamp connected to ground, probe the ETC fuse.

Does the test lamp illuminate?

Go to Step 8

Go to Step 6

6 |

1. Turn OFF the ignition.
2. Disconnect the powertrain control module (PCM).
3. Test the ETC voltage circuit for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 11

Go to Step 9

7 |

1. Turn OFF the ignition.
2. Disconnect the PCM.
3. Test the ETC voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .
4. Replace the fuse if necessary.

Did you find and correct the condition?

Go to Step 11

Go to Step 9

8 |

1. Turn OFF the ignition.
2. Disconnect the PCM.
3. Test the ETC voltage circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs .
4. Replace the fuse if necessary.

Did you find and correct the condition?

Go to Step 11

Go to Powertrain Relay Diagnosis

9 | Test for an intermittent and for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 11 | Go to Step 10
10 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 11 | --
11 |

1. Clear the DTCs with a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Does the DTC fail this ignition?

Go to Step 2

Go to Step 12

12 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | Go to Diagnostic Trouble Code (DTC) List - Vehicle | System OK