Technical Description of OBD-II Trouble Code
Malfunction in the Circuit of the Transmission Range Sensor (PRNDL input)
What does that signify?
This is a generic code that applies to all makes and models manufactured from 1996 onwards. However, the specific troubleshooting steps may vary depending on the vehicle.
The P0705 diagnostic trouble code (DTC) refers to a switch on the transmission, either internal or external, that signals the Powertrain Control Module (PCM) or the Transmission Control Module (TCM) about the gear shift position – P, R, N, and D (park, reverse, neutral, and drive). If it is an external component, the Transmission Range Sensor (TRS) may also control the backup lights.
This code indicates that the computer has detected a failure in the TRS sensor. The sensor is either sending an incorrect signal or no signal at all to the computer, which affects the identification of the gear position. The computer receives signals from both the vehicle speed sensor and the TRS.
When the vehicle is in motion and the computer receives conflicting signals, such as the TRS signal indicating that the vehicle is in park while the speed sensor indicates movement, the code P0705 is triggered.
As the vehicle ages and accumulates mileage, external TRS failure is common. It is exposed to weather and elements, and like any printed circuit, it tends to corrode over time. The advantage is that it is not an expensive repair and can be easily replaced even with minimal automotive repair experience.
Example of an external Transmission Range Sensor (TRS):
TRS image from Dorman
Newer models with the transmission range sensor located in the valve body present a different challenge. The range sensor is separate from the neutral safety switch and reverse backup light switch. Although its purpose remains the same, replacing it has become a more complex and costly task. The easiest way to determine which type is used in your vehicle is to check the part on your local auto parts website. If it is not listed, it is an internal sensor.
Symptoms
The symptoms of a P0705 DTC may include:
Potential Causes
The potential causes for this DTC may include:
Diagnostic Steps & Possible Solutions
Replacing an internal TRS requires using a Tech II for diagnosis, followed by draining the transmission and removing the pan. The sensor is located at the bottom of the valve body, which is responsible for all transmission functions. The sensor is constantly submerged in hydraulic fluid, which can cause issues with the casing. Often, hydraulic flow is restricted or O-ring sealing has initiated the problem.
In any case, this is a complex process that is best left to a transmission specialist.
Replacing external transmission range sensors:
Additional Note: The external TR sensor found on some Fords may be referred to as an MLPS or manual lever position sensor.
Related Transmission Range Sensor codes: P0705, P0706, P0707, P0708, and P0709.
