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 diagnostic category.

### DTC Descriptor

DTC P2533: Ignition 1 Switch Circuit
DTC P2533 06: Ignition 1 Switch Circuit Short to Ground or Open

### Circuit/System Description

The engine control module (ECM) uses the ignition 1 voltage circuit to monitor system voltage. Voltage that is out of range will cause damage to components and incorrect input readings.

### Conditions for Running the DTC

• | The ignition is ON.

• | The DTC runs once per ignition cycle once the above condition is met.

### Conditions for Setting the DTC

The ECM detects an open or a short to ground on the Ignition 1 Voltage Circuit.

### Action Taken When the DTC Sets

DTC P2533 is a Type B DTC.

### Conditions for Clearing the DTC

DTC P2533 is a Type B DTC.

### Reference Information

#### Schematic Reference

Engine Controls 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. Ignition ON, observe the scan tool ignition 1 data parameter. The reading should indicate the circuit is active.
2. Observe the DTC information with a scan tool. DTC P2533 should not set.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

### Circuit/System Testing

1. Ignition OFF, disconnect the ECM harness connector X1.
2. Ignition ON, test for battery voltage on the ignition 1 voltage circuit terminal X1-28.

⇒ | If less than the specified range, test the ignition 1 voltage circuit for an open or a short to ground.

3. Verify a test lamp illuminates between the ignition 1 voltage circuit terminal X1-28 and ground.

⇒ | If the test lamp does not illuminate, repair the ignition 1 voltage circuit for a high resistance.

4. If the circuit test normal, test or replace the ECM.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, setup, and programming