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 open fuse | P2534 | -- | P0562, P0563

### Circuit/System Description

The transmission control module (TCM) continuously monitors the system voltage on the Ignition 1 voltage circuit. 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 for 5 seconds.

• | Ignition voltage is between 9.0 volts and 19.0 volts.

### Conditions for Setting the DTC

The TCM detects 2 volts or less on the ignition 1 voltage circuit at the TCM for 6 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.

• | The TCM inhibits TU TD/MUMD operation.

### Conditions for Clearing the DTC

DTC P2534 is a Type A DTC.

### Diagnostic Aids

• | Observe the driver information center (DIC) messaging that would indicate the electrical system requires service.

• | Inspect for the following conditions:

- | Loose or damaged terminals at the generator

- | Loose or worn generator drive belt

### Reference Information

#### Schematic Reference

Automatic Transmission Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

• | Transmission General Description

• | Transmission Component and System Description

• | Electronic Component Description

#### 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

DT-48616-10 Adapter Harness

For equivalent regional tools, refer to Special Tools.

### Circuit/System Verification

1. Engine ON, accessories OFF, measure and record the battery voltage at the battery terminals. The voltage should be between 12.6-15.0 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 12.6-15.0 volts.
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 14-way harness connector at the transmission.
2. Connect the DT-48616-10 harness to the 14-way transmission harness connector.
3. Test for less than 10 ohms between the ground circuit terminal 2 and ground.

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

4. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminals listed below and ground.

• | Terminal 1

• | Terminal 12

• | Terminal 13

⇒ | 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 control solenoid (w/body and TCM) valve assembly.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

| Note: Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection.

• | Refer to Control Module References for control solenoid (w/body and TCM) valve assembly replacement, setup, and programming.

• | Perform the Service Fast Learn Adapts following all transmission related repairs.