P1904 – OBD-II DTC

OBD-II DTC P1904 – Transmission Transfer Case Contact Plate Ground Return Open Circuit

DTC P1904 meaning

DTC P1904 refers to a diagnostic trouble code indicating an open circuit in the ground return for the transmission transfer case contact plate. This code is specific to the communication between the transfer case and the vehicle’s control module, which is essential for proper operation of the transmission system.

DTC P1904 symptoms

Common symptoms associated with DTC P1904 may include:

• Transmission shifting issues
• Inability to engage or disengage the transfer case
• Warning lights on the dashboard, such as the check engine light
• Unusual noises from the transmission area
• Reduced vehicle performance

DTC P1904 causes

The causes of DTC P1904 can vary, but typical reasons include:

• Faulty ground connection or wiring issues
• Defective transfer case contact plate
• Corrosion or damage to electrical connectors
• Malfunctioning control module
• Short circuits or open circuits in the wiring harness

DTC P1904 seriousness

DTC P1904 is considered a serious issue as it can affect the vehicle’s ability to shift gears properly and engage the transfer case. If left unaddressed, it may lead to further transmission damage or complete failure, resulting in costly repairs and potential safety hazards while driving.

How to diagnose DTC P1904

To diagnose DTC P1904, follow these steps:

1. Use an OBD-II scanner to confirm the presence of the P1904 code.
2. Inspect the wiring and connectors related to the transfer case for any visible damage or corrosion.
3. Check the ground connections for continuity and ensure they are secure.
4. Test the transfer case contact plate for proper operation.
5. Examine the vehicle’s control module for any faults or updates needed.

How to fix DTC P1904 step-by-step instructions

To fix DTC P1904, follow these step-by-step instructions:

1. Disconnect the vehicle’s battery to ensure safety while working on electrical components.
2. Inspect and repair any damaged wiring or connectors related to the transfer case.
3. Clean any corrosion found on electrical connections to ensure good conductivity.
4. Replace the transfer case contact plate if it is found to be defective.
5. Reconnect the battery and clear the DTC using an OBD-II scanner.
6. Test drive the vehicle to ensure the issue is resolved and the code does not return.

How to erase DTC P1904

To erase DTC P1904, follow these steps:

1. Connect an OBD-II scanner to the vehicle’s diagnostic port.
2. Turn on the ignition without starting the engine.
3. Navigate to the option to clear or erase trouble codes on the scanner.
4. Confirm the action to erase the DTC.
5. Disconnect the scanner and start the vehicle to check if the code reappears.

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