P0705 Transmission Range Sensor Circuit Malfunction (PRNDL Input)

What Does P0705 Mean?

The diagnostic trouble code (DTC) P0705 in your vehicle’s computer means that the sensor (Range Switch) that monitors what gear the transmission is in has experienced a fault and set a code in the Engine Control Module (ECM).

The range switch (Park Neutral or PRNDL Switch) sends a signal to the ECM to tell it what gear the transmission is in. When the vehicle is put into a gear (P,R,D etc) it completes a circuit. Each individual circuit carries varying voltages that the ECM interprets.

If the ECM sees a signal that is not logical or out of range, it will set the DTC P0705.

Symptoms of P0705

  • Check Engine Light
  • No start (park or neutral)
  • No dash indicator (PRNDL)
  • Erratic shifting
  • No Reverse lights
  • Having to wiggle shift lever start
  • Having to put vehicle in neutral (N) to start

Causes of P0705 Code

The most common cause would be from a defective range switch that has an open or short within the component. In this case, the range sensor is getting the right input from the driver but cannot relay the message properly to the ECM. If the sensor is out of adjustment, it may be able to send a signal but it will send the wrong message to the ECM and trigger the code P0705.

Transmission Range Sensor

Sometimes the range switch can get moved slightly causing a misalignment of the switch. The code could also come from a problem with the ECM or TCM however this would usually produce other codes that would help in diagnosing the problem.

If the transmission fluid is low or contaminated it might produce problems within the valve body responsible for shifting gears and give the P0705 code. Other causes include:

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  • A defective or faulty range switch
  • A switch that is out of adjustment
  • A faulty TCM or ECM
  • Poor transmission fluid
  • Problem within valve body

How to Diagnose the P0705 Code?

It’s always a good practice to start any transmission diagnostic by checking the fluid level and condition of the transmission.

Assuming all is right with the fluid, you can then inspect the electrical connection on the TRS by checking for proper power/ground specs. If the switch is mounted externally it is susceptible to road debris and moisture and may have a bad connection.

If you believe that the connection is good you can start checking for power/ground/volt reference. You will need to get a wiring schematic to ensure you check the proper wires and that your readings are correct. Someone may have to sit in the car and shift gears so you can check all inputs and outputs.

Depending on the style, the range switch (contact, variable resistor, pressure) can be tested if you have the proper tool, namely, a digital multi meter. A multi meter can easily test voltage changes or resistance in circuit and an auto ranging multimeter will be your best option for diagnosing. If all sensors test good you will have to check the circuit for opens or shorts if the code does not specify a short to power or ground.

Common Mistakes When Diagnosing P0705 Code

As with any transmission diagnostic, mechanical or electrical, the first step should always be to check the fluid level and condition. All vehicle have a slightly different method for checking transmission fluid level so you have to be sure all conditions are met before taking a measurement.

Low or contaminated transmission fluid can lead to several troubling problems. Also make sure the switch is properly aligned before deciding to replace it and, conversely, make sure it is properly aligned after installation.

What Repairs Will Fix the P0705 Code?

Changing a defective switch will fix that problem but proper alignment will have to be set before repairs are complete so begin by learning the adjustment procedure.

The wiring harness will have to be thoroughly checked if a broken wire is suspected.

If low fluid or contamination is present a proper flush may fix the problem if there hasn’t already been excessive damage.

A closed circuit, preferably heated flush machine should be used to make sure all dirty fluid is evacuated otherwise debris may stay in the system and the problem could return. If you found the switch was only out of adjustment, look for any signs of damage that might have caused it to move or when reassembling check for proper torque specs (if any) when re-mounting.

Codes Related to P0705

Related Transmission Range Sensor codes: P0706, P0707, P0708, and P0709.

It would not be uncommon for this to be the only code you find but it may also be associated with something more severe.

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