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

### 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 speed is greater than 500 RPM.

• | Ignition voltage is between 8-18 volts.

### Conditions for Setting the DTC

The TCM detects 2 volts or less on the ignition 1 voltage circuit at the TCM for 10 seconds or more.

### Action Taken When the DTC Sets

• | DTC P2534 is a Type A DTC.

• | The TCM turns OFF all high side drivers.

• | The TCM turns OFF all solenoids.

• | The TCM commands maximum line pressure.

• | the TCM freezes transmission adaptive functions.

• | The TCM commands the TCC OFF.

• | The TCM allows the vehicle to operate in transmission protection mode.

### Conditions for Clearing the DTC

DTC P2534 is a Type A DTC.

### Diagnostic Aids

If all circuit tests are OK, make sure the transmission pass through connector and harness terminals are clean and not damaged, and the charging system is functioning correctly.

### Reference Information

#### Schematic Reference

Automatic Transmission 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

### Circuit/System Testing

Clear the DTC and operate the vehicle under the conditions for running and setting the DTC.

If the DTC resets, test the TCM ignition 1 voltage circuit for battery positive voltage at the TCM 16-way connector.

If the voltage is less than battery voltage, test the Ignition 1 voltage circuit for an open or short to ground and repair the circuit as necessary.

### Repair Instructions

Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Perform the Service Fast Learn Adapts.