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 P0381: Wait to Start Lamp Control Circuit
DTC P0381 01: Wait to Start Lamp Control Circuit Short to Battery
DTC P0381 02: Wait to Start Lamp Control Circuit Short to Ground
DTC P0381 04: Wait to Start Lamp Control Circuit Open Circuit
DTC P0381 54: Wait to Start Lamp Control Circuit Temperature High

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Voltage Supply | P0381, P0381 02 | P0381, P0381 04 | -- | --
Control Circuit | P0381, P0381 02 | P0381, P0381 04 | P0381, P0381 01 | P0381 54

### Circuit/System Description

The Wait to Start lamp is located on the instrument panel cluster (IPC). The lamp informs the driver when to start the engine. The engine control module (ECM) monitors the lamp control circuit for conditions that are incorrect for the commanded state of the lamp. For example, a failure condition exists if the ECM detects low voltage when the lamp is commanded OFF, or high voltage when the lamp is commanded ON.

### Conditions for Running the DTC

• | The ignition is ON.

• | The ignition voltage is between 8.5-16.5 volts.

• | DTC P0381 runs continuously once the above conditions are met.

### Conditions for Setting the DTC

#### P0381 01

The ECM detects a short to voltage on the circuit that controls the lamp.

#### P0381 02

The ECM detects a short to ground on the circuit that controls the lamp.

#### P0381 04

The ECM detects an open on the circuit that controls the lamp.

#### P0381 54

The ECM detects that the internal output driver is over temperature.

### Action Taken When the DTC Sets

DTC P0381 is a Type C DTC.

### Conditions for Clearing the DTC

DTC P0381 is a Type C 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

Ignition ON, command the lamp ON and OFF with a scan tool. The lamp should turn ON and OFF as commanded.

### Circuit/System Testing

1. If any other IPC indicators or gages are inoperative, refer to Symptoms - Displays and Gages.
2. Ignition OFF, disconnect the ECM harness connectors. Ignition ON, the lamp should not illuminate.

⇒ | If the lamp is illuminated, test the lamp control circuit for a short to ground. If the circuit tests normal, replace the IPC.

3. Ignition ON, install a 3A fused jumper wire between the lamp control circuit and ground. The lamp should illuminate.

⇒ | If the lamp does not illuminate, test the lamp control circuit for a short to voltage, or an open/high resistance. If the circuit tests normal, replace the IPC/bulb.

4. If all circuits test normal, replace the ECM.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Instrument Cluster Replacement

• | Instrument Cluster Bulb Replacement

• | Control Module References for engine control module replacement, setup, and programming