Technical Description of OBD-II Trouble Code
Circuit for Displaying Transmission Range
What does that signify?
This diagnostic trouble code (DTC) is a generic powertrain code that is applicable to many OBD-II vehicles (1996-newer). This includes vehicles from Mercedes-Benz, Jaguar, Range Rover, Ford, Volvo, Sprinter, etc. Although it is a generic code, the specific repair steps may vary depending on the year, make, model, and powertrain configuration.
If your vehicle has stored a code P0814, it means that the powertrain control module (PCM) has detected a malfunction in the circuit for displaying the transmission range. This code is limited to vehicles with automatic transmissions.
The transmission control module (TCM) may be a standalone module or part of the PCM. The transmission range display sensor is often integrated into the neutral safety switch. The shift shaft actuates the transmission range display sensor, which provides a voltage signal to the PCM and the instrument panel control module (IPCM) to indicate the specific gear selected. The PCM monitors various engine and transmission outputs to ensure that the transmission range display sensor is in the correct position. Additionally, the PCM monitors the circuit voltage of the transmission range sensor to ensure that it falls within the established parameters.
If the PCM detects that the vehicle is moving in a manner that does not align with the gear selection input from the transmission range display sensor, or if the circuit voltage is outside the allowable parameters, a code P0814 may be stored and the malfunction indicator lamp (MIL) may illuminate. Multiple ignition cycles (with a failure) may be necessary for the MIL to illuminate.
What is the severity of this DTC?
A stored code P0814 indicates that either a serious electrical issue or some type of mechanical failure has occurred. In any case, it is important to rectify the conditions that led to the storage of this code as quickly as possible.
What are some of the symptoms of the code?
Symptoms of a P0814 trouble code may include:
What are some of the common causes of the code?
Possible causes for this code may include:
What are some P0814 troubleshooting steps?
To diagnose a code P0814, you will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information.
You can use your source of vehicle information to find a technical service bulletin (TSB) that matches the vehicle’s year, make, and model, as well as the engine size, stored code/s, and exhibited symptoms. If you find a TSB, it may provide helpful diagnostic information.
Use the scanner (connected to the vehicle’s diagnostic connector) to retrieve all stored codes and relevant freeze frame data. It is advisable to write down this information before clearing the codes, and 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 point, the code is intermittent and may be more challenging to diagnose. In such cases, the conditions that led to the storage of the code may need to worsen before an accurate diagnosis can be made.
If the code is immediately reset, the next step in your diagnosis will involve searching your vehicle information source for diagnostic flowcharts, connector pin-out charts, connector face views, and component testing procedures/specifications.
Step 1
Use the DVOM to test the voltage, ground, and signal output at the transmission range display sensor or neutral safety switch. The input and output circuits of the transmission range display sensor typically consist of either reference voltage (when the transmission is in gear) or ground (when the transmission is in park or neutral).
Step 2
If the system circuits are functioning properly, use the DVOM to test the transmission range display sensor. Replace any sensors that do not test within the system specifications.
