P0818 Driveline Disconnect Switch Input Circuit

Description and meaning of DTC p0818

This diagnostic trouble code (DTC) is a generic powertrain code and applies to many OBD-II vehicles (1996-newer). That may include but is not limited to vehicles from Toyota, Land Rover, Volvo, BMW, Mini, Jaguar, etc. Although generic, the exact repair steps may vary depending on year, make, model and powertrain configuration. If your vehicle has stored a code P0818, it means that the powertrain control module (PCM) has detected a malfunction in the transfer case neutral safety switch (also called the shift selector switch) circuit. This type of code is applicable to vehicles with automatic AWD/4WD transmissions only. The transfer case neutral safety switch input circuit is typically integrated into the neutral safety switch or shift selector switch. When the transfer case is placed in neutral (driveline disconnected), a voltage signal is input to the transmission control module (TCM) or the PCM. The controller also monitors transfer case neutral safety switch circuit voltage whenever the ignition is in the ON position. The TCM may be a stand alone module or part of the PCM. If the PCM does not detect an appropriate degree of voltage on the transfer case neutral safety switch circuit, with the transfer case apparently in or neutral, a code P0818 may be stored and a malfunction indicator lamp (MIL) illuminated. Multiple ignition cycles (with a failure) may be required for MIL illumination.

p0818 diagnostic trouble code symptoms

Symptoms of a P0818 trouble code may include:Engine will not startFront axle fails to engage or will not disengageEngine starts with the transmission in gearNo symptoms may be exhibited

DTC p0818 - possible causes

Causes for this code may include:Defective neutral safety or shift selector switchShorted or open wiring or connectors in transfer case neutral safety switch input circuitFaulty PCM or a programming error

How to fix OBD-II diagnostic trouble code p0818

A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle specific diagnostic information will be required to diagnose a code P0818. You may use your source of vehicle information to locate a technical service bulletin (TSB) that matches the vehicle year, make, and model as well as the engine size, code/s stored, and symptoms exhibited. If you find one, it could yield helpful diagnostic information. 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.

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