Wiring Systems and Power Management
DTC P2534 or P2535
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 Descriptors
DTC P2534
- Ignition On/Start Switch Circuit Low Voltage
DTC P2535
- Ignition On/Start Switch Circuit High Voltage
Diagnostic Fault Information
Circuit/System Description
The transmission control module (TCM) samples the system voltage on the Ignition 1 voltage circuit every.1 s. 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
P2534
The TCM ignition voltage signal is valid, with the ignition ON.
P2535
The TCM ignition voltage signal is valid, with the ignition OFF.
Conditions for Setting the DTC
P2534
The TCM detects 6 V or less on the ignition voltage circuit, with the ignition turned ON.
P2535
The TCM detects greater than 6 V or greater on the ignition voltage circuit, with the ignition turned OFF.
Action Taken When the DTC Sets
P2534
* DTC P2534 is a Type A DTC.
* The TCM turns the high side driver OFF.
* 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.
P2535
DTC P2535 is a Type A DTC.
Conditions for Clearing the DTC
DTCs P2534 and P2535 are Type A DTCs.
Diagnostic Aids
If all circuit test normal, 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 6T40 (MH8,MHH) - Automatic Transmission
Connector End View Reference
Component Connector End Views Sunshade - Left
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 running.
2. Verify the scan tool TCM Ignition 1 Signal parameter is between 12.6-15 V.
• If not between 12.6-15 V
Refer to Circuit/System Testing.
• If between 12.6-15 V
3. Verify that the DTC does not set by operating the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions you observe from the Freeze Frame/Failure Records data. If the vehicle passes the Circuit/System Verification procedure, then STOP. Do not perform the Circuit/System Testing or Component Testing as this may result in an unnecessary part replacement. Refer to Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections.
Circuit/System Testing
1. Ignition OFF, and all vehicle systems OFF, disconnect the X1 harness connector at the T12 Automatic Transmission Assembly.
2. Test for less than 10 ohms between ground circuit terminal 2 and ground.
• If 10 ohms or greater
1. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 10 ohms
3. Ignition ON.
4. Verify a test lamp illuminates between B+ circuit terminal 1 and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF, remove the test lamp.
2. Test for less than 2 ohms in the B+ circuit end to end
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the fuse is good and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF, remove the test lamp.
2. Test for infinite resistance between the B+ circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If the test lamp illuminates
5. Ignition OFF.
6. Test for less than 1 V between the ignition circuit terminal 12 and ground.
• If 1 V or greater
Repair the short to voltage on the circuit.
• If less than 1 V
7. Ignition ON.
8. Verify a test lamp illuminates between terminal 12 and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF, remove the test lamp.
2. Test for less than 2 ohms in the ignition circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, refer to Power Mode Mismatch Power Mode Mismatch.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF, remove the test lamp.
2. Test for infinite resistance between the ignition circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If the test lamp illuminates
9. Replace the K71 Transmission Control Module.
Repair Instructions
* Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Refer to Control Module References Control Module References for transmission control module replacement, programming and setup