U1135 – OBD-II DTC

OBD-II DTC U1135 – SCP (J1850) Invalid or Missing Data for Ignition Switch / Starter

DTC U1135 meaning

DTC U1135 refers to a communication issue within the vehicle’s network, specifically related to the ignition switch or starter. This code indicates that the data from the ignition switch is either invalid or missing, which can disrupt the normal operation of the vehicle’s systems. The code is part of the On-Board Diagnostics II (OBD-II) system and is associated with the SCP (Serial Communication Protocol) using the J1850 standard.

DTC U1135 symptoms

Common symptoms associated with DTC U1135 may include:

• Engine not starting or intermittent starting issues
• Dashboard warning lights illuminated
• Loss of communication with other modules
• Erratic behavior of electrical components

DTC U1135 causes

Several factors can lead to the triggering of DTC U1135, including:

• Faulty ignition switch
• Wiring issues or damaged connectors in the ignition circuit
• Malfunctioning starter motor
• Defective body control module (BCM) or powertrain control module (PCM)
• Corrosion or poor connections in the vehicle’s electrical system

DTC U1135 seriousness

DTC U1135 is considered a moderate to serious issue. While it may not cause immediate catastrophic failure, it can lead to significant problems such as:

• Inability to start the vehicle
• Potential safety risks if the vehicle stalls unexpectedly
• Increased wear on other components due to erratic electrical behavior

How to diagnose DTC U1135

To diagnose DTC U1135, follow these steps:

1. Use an OBD-II scanner to confirm the presence of the U1135 code.
2. Check for any additional DTCs that may provide more context.
3. Inspect the ignition switch for proper operation and signs of wear.
4. Examine wiring and connectors for damage, corrosion, or loose connections.
5. Test the starter motor to ensure it is functioning correctly.
6. Verify the operation of the BCM and PCM, checking for software updates or faults.

How to fix DTC U1135 step-by-step instructions

To fix DTC U1135, follow these steps:

1. Address any identified issues with the ignition switch, replacing it if necessary.
2. Repair or replace damaged wiring and connectors in the ignition circuit.
3. Test and replace the starter motor if it is found to be faulty.
4. Check and, if needed, reprogram or replace the BCM or PCM.
5. Clear the DTC using an OBD-II scanner and perform a test drive to ensure the issue is resolved.

How to erase DTC U1135

To erase DTC U1135, follow these steps:

1. Connect an OBD-II scanner to the vehicle’s diagnostic port.
2. Turn the ignition key to the “On” position without starting the engine.
3. Access the DTC menu on the scanner and locate the U1135 code.
4. Select the option to clear or erase the DTC.
5. Turn off the ignition and disconnect the scanner.
6. Start the vehicle and monitor for the reappearance of the code.

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