P0706 Transmission Range Sensor A Circuit Range/Performance
OBD-II Trouble Code Technical Description
Generic: Transmission Range Sensor “A” Circuit Range/Performance
General Motors: Transmission range sensor performance
Jaguar: Dual linear switch signals missing
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to OBD-II equipped vehicles. Although generic, the specific repair steps may vary depending on make/model.
P0706 is a generic powertrain DTC in the transmission controls sub system group. This is a "C" type DTC. “C” type DTC’S are non-emission related so the powertrain control module (PCM) does not turn on the check engine light or store freeze frame data.
The transmission range sensor may be referred to as the park/neutral switch (PN), or the neutral safety switch. Its purpose is to inform the PCM of the position of the gear shifter and to allow the engine to start only in the park and neutral positions. The PCM sends a voltage reference to the sensor and the sensor sends a different voltage back the PCM depending on which gear the shifter is in. If the return voltage is not what it is supposed to be this code will set.
Example of an external Transmission Range Sensor (TRS):
TRS image from Dorman
Symptoms & Severity of Code
Because the neutral safety switch is part of the transmission range sensor the vehicle may start in any gear position and/or the PCM will force the transmission in to "limp" mode. In this mode there is an obvious lack of power, especially from a complete stop.
There is a serious safety concern when this code is present due to the possibility of the vehicle starting in gear causing it to start moving upon start up. This problem should be corrected immediately.
Causes
Potential causes for this code to set are:
Diagnostic and Repair Procedures
There are two possible conditions that will cause this code to set:
Condition #1-The PCM detects drive or reverse at vehicle start-up
Condition #2-The PCM detects park or neutral and the following conditions exist for 10 seconds or more: >Throttle position is 5% or more: >engine torque is greater than 50ft.lbs. >Vehicle speed is greater than 20 MPH
In my experience this code is most common on four wheel drive trucks that have been out "4-wheelin" and have had damage inflicted to the range sensor and/or harness. It would be very rare to have a faulty PCM be the cause of this code. diagnosis of this code is pretty straight forward. SET THE PARKING BRAKE.
Begin with a thorough visual inspection of the range sensor and wiring harness. Repair any damage found. Does the vehicle start in reverse/drive? If it does start, unplug the range sensor and try and start it in reverse/drive again. If it still starts, suspect a short in the harness. If it does not start, suspect a faulty or misadjusted range sensor.
Related Transmission Range Sensor codes: P0705, P0706, P0707, P0708, and P0709.
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"Delete Error Code Permanently, Disable DTC Error Code Function for p0706 in the ECU"
In extreme cases, we even have the option to permanently remove the specific DTC p0706 and disable the function of the specific error code in the ECU. All other fault code functions will then continue to work to protect the engine. This is different from clearing an error code with a diagnostic device. We have the option to permanently remove the function of the specific error code, so that it never comes back. Also emergency running that occurs on the specific error code can be solved in most cases.
Of course we prefer to first try to solve the cause of the error code, but sometimes the only solution is to permanently disable the DTC function of p0706.
