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Error Code P081C is defined as Park Input Circuit. Error Code P081C is a generic trouble code, meaning it applies to all vehicles with the OBD-II system, especially those made from 1996 up to present. This includes vehicles from, but not limited to, BMW, Jaguar, Land Rover, Mini, and Volvo. Specifications on the definition, troubleshooting, and repairs, of course, vary between make, model, and powertrain configuration.
If the vehicle stores the Error Code P081C, this means the PCM (powertrain control module) has determined a fault in the PARK input circuit of the neutral safety switch (also known as the shift selector switch). This code only applies to vehicles with automatic transmission.
The PARK input circuit is usually integrated into the neutral safety switch or the selector switch. If the transmission is placed in the park position, a voltage signal is sent into the TCM (transmission control module) or PCM. The controller also monitors the circuit voltage each time the ignition is at the ON position. The TCM can be a standalone module or part of the PCM.
This error code will be set if the PCM is unable to detect the right degree of voltage at t circuit, with the transmission apparently in the park or neutral, along with the activation of the MIL (malfunction indicator lamp). In some cases, multiple failure cycles may be needed to activate the MIL.
- Engine no start condition
- The engine starts with the transmission in gear
In other cases, the problem may not exhibit any symptoms at all.
- Defective neutral safety or shift selector switch
- Shorted or open wiring in the connectors or PARK input circuit
- Defective or programming error in PCM
How to Check
You will also need a diagnostic scanner, DVOM (digital volt/ohmmeter), and a source of vehicle diagnostic information.
Use the vehicle’s information to find the TSB (technical service bulletin) that matches the specifics of the vehicle (make, model, engine size, symptoms, and codes stored). This could help for a more thorough diagnosis.
Use the scanner (connected to the vehicle diagnostic connector) to retrieve all stored codes and pertinent freeze frame data. It is a good idea to write this information down before clearing the codes then test-drive the vehicle until the PCM either enters readiness mode, or the code is reset.
If the PCM enters readiness mode at this time, the code is intermittent and may be much more difficult to diagnose. If this is the case, the conditions which contributed to the code being stored may need to worsen before an accurate diagnosis can be made.
If the code is immediately reset, the next step of your diagnosis will require that you search your vehicle information source for diagnostic flow-charts, connector pin-out charts, connector face views, and component testing procedures/specifications.
Using the DVOM, test the PARK input voltage at the appropriate neutral position/shift selector switch. Usually, the PARK input circuit consists of either the battery voltage (activated) or ground (deactivated).
Using the vehicle diagnostic information and the DVOM, test the neutral safety/shift selector switches as needed. Switches that don’t test within the system parameters must be removed and replaced.
If the circuits and system switches are in working condition, then test the PARK input circuits to the PCM using the DVOM. Make sure you disconnect all controllers before using the DVOM for testing.
How to Fix
- Repair or replacement of neutral safety switch or shift selector switch
- Repair or replacement of shorted or open wiring or connector PARK input circuit
- Defective or programming error in the PCM
PARK input codes are usually related to neutral safety switch failure.
This error code is usually accompanied with a no-start condition, which indicates that the problem is either an electrical problem or mechanical failure. Conditions like this must be addressed as soon as possible.