For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each of the diagnostic category.

### DTC Descriptor

DTC P1682: Ignition 1 Switch Circuit 2

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Ignition 1 Voltage (Powertrain Relay) | P0689, P1682, P2176 | P0689, P1516, P1682, P2101 | P0690 | --
Ignition 1 Voltage (Run/Crank Relay) | -- | P1682 | P0575, P0650 | --

### Typical Scan Tool Data

#### EC Ignition Relay Feedback

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Operating Conditions: Ignition ON Engine OFF. Powertrain Relay commanded ON
Ignition 1 voltage | 0 volts | 0 volts | 12 volts

#### Ignition 1 Signal

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Operating Conditions: Ignition ON Engine OFF. Run/Crank Relay commanded ON
Ignition 1 voltage | 0 volts | 0 volts | 12 volts

### Circuit/System Description

There are 2 ignition 1 voltage circuits supplied to the engine control module (ECM). The first ignition 1 voltage circuit is provided by the powertrain relay, through a fuse. This ignition 1 voltage circuit supplies power to all the internal ECM circuits associated with the throttle actuator control (TAC) operation. The run/crank relay provides the second ignition 1 voltage circuit to the ECM, through a fuse. This ignition 1 voltage provides power to other internal ECM circuits, except those associated with TAC operation. The ECM continuously monitors the voltage level difference between the two circuits.

### Conditions for Running the DTC

• | The ignition is in the Unlock/Accessory, Run, or Crank position.

• | System voltage is more than 5.23 volts.

• | Powertrain relay is commanded ON

• | DTC P1682 runs continuously when the above conditions are met.

### Conditions for Setting the DTC

The ignition 1 voltage of the Run/Crank relay is more than 3 volts different than the ignition 1 voltage of the powertrain relay for more than 2 seconds.

### Action Taken When the DTC Sets

DTC P1682 is a Type A DTC.

Engine may operate in a reduced engine power mode.

### Conditions for Clearing the DTC

DTC P1682 is a Type A DTC.

### Diagnostic Aids

This test procedure requires that the vehicle battery has passed a load test and is completely charged. Refer to Battery Inspection/Test.

### Reference Information

#### Schematic Reference

• | Engine Controls Schematics

• | Power Distribution Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. If DTCs P0685, P0689, P0690, or B1380 are set, diagnose those DTCs first.
2. Ignition ON, engine OFF, observe the Ignition 1 Voltage Signal, and the EC Ignition Relay Feedback Signal parameters, on the scan tool. Both parameter values should display no more than 3 volts difference, between the two parameters.
3. Ignition OFF, observe the Ignition 1 Voltage Signal parameter on the scan tool. The parameter value should be 0 volts, before the ECM powers down.

### Circuit/System Testing

1. Ignition OFF, disconnect the Powertrain Relay.
2. Ignition ON, verify that a test lamp does not illuminate between the powertrain relay controlled output circuit terminal and ground.

⇒ | If the test lamp illuminates, test the powertrain relay controlled output circuit for a short to voltage.

3. Ignition OFF, verify that a test lamp illuminates between the powertrain relay coil voltage supply circuit terminal and ground.

⇒ | If the test lamp does not illuminate, test the powertrain relay coil voltage supply circuit for a short to ground or an open/high resistance.

4. Verify that a test lamp illuminates between the powertrain relay switch voltage supply circuit terminal and ground.

⇒ | If the test lamp does not illuminate, test the powertrain relay switch voltage supply circuit for an open/high resistance.

5. Disconnect the ECM.
6. Ignition ON, verify that a test lamp illuminates between ECM connector terminal 19 X1 and ground.

⇒ | If the test lamp does not illuminate, test the RUN/CRNK Relay controlled output circuit for a short to ground or open/high resistance. If the circuit tests normal and its fuse is open, replace the ECM.

7. Ignition OFF, connect the harness connector at the ECM.
8. Ignition ON, connect a 3A fused jumper wire between the powertrain relay voltage supply circuit terminal and the powertrain relay controlled output circuit terminal. Verify the EC Ignition Relay Feedback parameter indicates battery positive voltage.

⇒ | If not the specified value, test the powertrain relay controlled output circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, replace the ECM.

9. If all circuits test normal, replace the Powertrain Relay.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Relay Replacement

• | Control Module References for ECM replacement, setup, and programming