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 P2534: Ignition 1 Switch Circuit Low Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Ignition 1 Voltage | P2534 | P2534 | -- | P0562, P0563

### Typical Scan Tool Data

#### Ignition 1 Switch Parameter Data

Circuit | Normal | Short to Ground | Open/High Resistance | Short to Voltage
--- | --- | --- | --- | ---
Operating Conditions: Engine running in Park, normal operating temperature Parameter Normal Range: 12.0-14.5 volts
Ignition Voltage | 12.0-14.5 V | 0 V | 0 V | 12.0-14.5 V

### Circuit/System Description

The transmission control module (TCM) samples the system voltage on the Ignition 1 voltage circuit every 0.1 seconds. Lower than normal voltage may be inadequate to operate the transmission control solenoids properly. Improper solenoid operation may cause erratic transmission operation, which may result in internal damage.

### Conditions for Running the DTC

The engine is running.

### Conditions for Setting the DTC

The TCM detects an open or short to ground on the Ignition 1 voltage circuit.

### Action Taken When the DTC Sets

• | DTC P2534 is a Type A DTC.

• | The TCM commands maximum line pressure.

• | The TCM commands an immediate landing to 2nd gear.

• | The TCM freezes transmission adaptive functions.

### Conditions for Clearing the DTC

DTC P2534 is a Type A DTC.

### Reference Information

#### Schematic Reference

Automatic Transmission Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Charging System Description and Operation

#### 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

#### Special Tools

J 44152 Jumper Harness (20 pins)

### Circuit/System Verification

1. Engine running, accessories OFF, measure and record the battery voltage at the battery terminals. The voltage should be between 12.6 and 14.5 volts.

⇒ | If not within the specified range, refer to Charging System Test .

2. Observe the scan tool TCM Ignition voltage parameter. The reading should be between 12.6 and 14.5 volts.
3. 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 data.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the TCM.
2. Test for less than 10 ohm of resistance between the ground circuit terminal 49 and ground.

⇒ | If greater than the specified range, test the ground circuit for an open/high resistance.

3. Verify that a test lamp illuminates between the B+ circuit terminal 32 and ground.

⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

4. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 31 and ground.

⇒ | If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.

5. If all circuits test normal, replace the TCM.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for TCM replacement, setup, and programming.