6L50/6L80/6L90 - Automatic Transmission

DTC P2534

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (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 8.6-19.0 volts.
* The engine run/crank voltage signal from the ECM is valid.
* Serial data communications is enabled.

Conditions for Setting the DTC

The TCM detects 6 volts or less on the ignition 1 voltage circuit at the TCM for 1.0 second or more.

Action Taken When the DTC Sets

* DTC P2534 is a Type A DTC.
* The TCM turns OFF HSD1 and HSD2.
* 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 disables Tap up and Tap down functions.

Conditions for Clearing the DTC

DTC P2534 is a Type A DTC.

Diagnostic Aids

If all circuit tests are OK, ensure 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 (6L45/6L50/6L80/6L90 - Automatic Transmission)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Description and Operation

* Transmission General Description (Transmission General Description)
* Transmission Component and System Description (Transmission Component and System Description)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

Control Module References (Control Module References) for scan tool information

Circuit/System Verification

1. Engine ON, accessories OFF, measure and record the battery voltage with a DMM. The battery voltage should be between 12.5-14.5 volts.

• If the voltage is not within the specified value, or the charge indicator light is ON, refer to Symptoms - Engine Electrical (Symptoms - Engine Electrical).

2. Observe the scan tool TCM Ignition Voltage parameter. The reading should be between 12.5-14.5 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 X1 16-way harness connector at the T12 automatic transmission assembly.
2. Ignition OFF, test for less than 5 ohms on the vehicle harness connector X1 terminal 5 and ground at the transmission case.

• If greater than the specified value, test the ground circuit for an open/high resistance.

3. Ignition ON, verify that a test lamp illuminates at connector X1 vehicle harness side and the following terminals:

* Terminal 4 and ground at the transmission case
* Terminal 12 and ground at the transmission case

• If the test lamp does not illuminate on any circuit, test the ignition or B+ circuit for a short to ground or an open/high resistance.

4. If all circuits test normal, replace the Q8 control solenoid valve assembly.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

Perform the Service Fast Learn Adapts (6L45/6L50/6L80/6L90 - Automatic Transmission) following all transmission related repairs.