P2535
DTC P2535
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
DTC Descriptor
DTC P2535
- Ignition One Voltage High
Diagnostic Fault Information
Circuit Description
The ignition 1 relay is controlled by the body control module (BCM). The ignition 1 relay contacts are supplied a hot at all times from the fuse block underhood. The relay supplies power to several components when the vehicle is in the RUN or CRANK power mode. When the ignition switch is placed in the RUN or CRANK position, the BCM will receive an ignition 1 signal from the ignition switch and turn ON the ignition 1 relay. When the ignition switch is in the OFF position, the BCM will turn OFF the ignition 1 relay. The powertrain control module (PCM) compares the ignition 1 relay output signal with the BCM class 2 serial data power mode message. If the ignition 1 voltage signal and the power mode message do not match for an allotted time, the PCM will disable the fuel injectors and DTC P2535 will set.
Conditions for Running the DTC
* The vehicle is in PARK or NEUTRAL.
* The ignition switch is OFF.
Conditions for Setting the DTC
The ignition 1 voltage signal is higher than normal for more than 7 seconds.
Action Taken When the DTC Sets
* The control module stores the DTC information into memory when the diagnostic runs and fails.
* The malfunction indicator lamp (MIL) will not illuminate.
* The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
* The driver information center, if equipped, may display a message.
Conditions for Clearing the DTC
* A current DTC Last Test Failed clears when the diagnostic runs and passes.
* A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
Diagnostic Aids
* A history DTC maybe caused by an intermittent condition. Refer to Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics).
* There are different fuse blocks and different relays between the LS4 (V8) engine and the L26/L32 (V6) engines. Be sure to use the correct references and diagnostic tests listed below.
Reference Information
Schematic Reference
* Engine Controls Schematics (Electrical Diagrams) for the 3.8L engine
* Engine Controls Schematics (Electrical Diagrams) for the 5.3L engine
Connector End View Reference
Component Connector End Views (Connector Views)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning) for Scan Tool Information
Circuit/System Verification
Ignition ON, command the Ignition Power Relay ON and OFF with a scan tool. Feel/listen for the relay to click.
Circuit/System Testing
L26, L32
1. Ignition OFF, disconnect the IGN 1 Relay 37.
2. Verify a test lamp does not illuminate between the ignition 1 voltage circuit terminal A8 and ground.
• If the test lamp illuminates, test the ignition 1 voltage circuit for a short to voltage. If the circuit tests normal, replace the BCM.
3. Reconnect the IGN 1 Relay 37, and disconnect the harness connector X1 of the PCM.
4. Verify a test lamp does not illuminate between the ignition 1 voltage circuit terminal 19 and ground.
• If the test lamp illuminates, test the ignition 1 voltage circuit for a short to voltage. If the circuit tests normal, replace the IGN 1 Relay 37.
5. If all circuits test normal, replace the PCM.
LS4
1. Ignition OFF, disconnect the harness connector X4 of the underhood fuse block.
2. Verify a test lamp does not illuminate between the ignition 1 voltage circuit terminal H1 and ground.
• If the test lamp illuminates, test the ignition 1 voltage circuit for a short to voltage. If the circuit tests normal, replace the BCM.
3. Reconnect the harness connector of the underhood fuse block, and disconnect the harness connector X1 of the ECM.
4. Verify a test lamp does not illuminate between the ignition 1 voltage circuit terminal 19 and ground.
• If the test lamp illuminates, test the ignition 1 voltage circuit for a short to voltage. If the circuit tests normal, replace the underhood fuse block.
5. If all circuits test normal, replace the ECM.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Relay Replacement (Attached to Wire Harness) (Relay Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (Relay Replacement (Within an Electrical Center))
* Control Module References (Programming and Relearning) for module replacement, setup, and programming
* Underhood Electrical Center or Junction Block Replacement (Underhood Electrical Center or Junction Block Replacement)