C1859 – OBD-II DTC

OBD-II DTC C1859 – PRNDL Input #2 Circuit Failure

DTC C1859 meaning

DTC C1859 refers to a fault in the PRNDL (Park, Reverse, Neutral, Drive, Low) input #2 circuit. This code indicates that the vehicle’s transmission control module (TCM) has detected an issue with the signal from the PRNDL switch, which is responsible for indicating the current gear selection to the TCM. A failure in this circuit can lead to improper transmission operation and may affect the vehicle’s drivability.

DTC C1859 symptoms

Common symptoms associated with DTC C1859 may include:

• Transmission not shifting properly
• Inability to shift into certain gears
• Check Engine Light or Transmission Light illuminated
• Erratic or unexpected vehicle behavior
• Vehicle may go into limp mode

DTC C1859 causes

Several factors can lead to the occurrence of DTC C1859, including:

• Faulty PRNDL switch
• Wiring issues, such as shorts or open circuits
• Corroded or loose connectors
• Faulty transmission control module (TCM)
• Software issues within the TCM

DTC C1859 seriousness

DTC C1859 is considered a serious issue as it can affect the vehicle’s transmission performance. If left unaddressed, it may lead to further transmission damage or failure, impacting safety and drivability. It is advisable to diagnose and repair this issue promptly to ensure safe operation of the vehicle.

How to diagnose DTC C1859

To diagnose DTC C1859, follow these steps:

1. Use an OBD-II scanner to confirm the presence of DTC C1859.
2. Inspect the PRNDL switch for any visible damage or wear.
3. Check the wiring and connectors associated with the PRNDL input circuit for shorts, opens, or corrosion.
4. Test the PRNDL switch using a multimeter to ensure it is functioning correctly.
5. Examine the TCM for any fault codes or software issues.
6. Clear the codes and perform a road test to see if the code reappears.

How to fix DTC C1859 step-by-step instructions

To fix DTC C1859, follow these steps:

1. Repair or replace any damaged wiring or connectors found during diagnosis.
2. If the PRNDL switch is faulty, replace it with a new one.
3. Ensure all connections are secure and free of corrosion.
4. If the TCM is suspected to be faulty, consider reprogramming or replacing it.
5. After repairs, clear the DTC using an OBD-II scanner.
6. Perform a road test to confirm that the issue has been resolved and the code does not return.

How to erase DTC C1859

To erase DTC C1859, 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 scanner’s menu and select the option to clear or erase trouble codes.
4. Confirm the action and wait for the scanner to complete the process.
5. Disconnect the scanner and start the vehicle to ensure the code does not reappear.

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