P0705: Transmission Range Sensor Circuit Malfunction (PRNDL Input)

What is P0705?

Diagnostic Trouble Code (DTC) P0705 is defined as “Transmission Range Sensor Circuit Malfunction (PRNDL Input).” It’s a generic powertrain code commonly found in vehicles made after 1996.

Fault code P0705 occurs when the Transmission Control Module (TCM) or Engine Control Module (ECM) receives an input error from the Transmission Range Sensor (TRS).

The TRS sensor is responsible for telling the TCM or ECM the position of the gear shift lever. It’s also sometimes called the ParkNeutral Position switch (PNP switch), the gear selection switch, or the PRNDL input switch.

A faulty Transmission Range Switch may fail to send an input to the ECM. Alternatively, it could send an illogical input, such as reporting that the vehicle is in reverse when the selector lever is in drive.

For either condition, the Engine Control Module will trigger code P0705 and turn on the Check Engine Light. It’s also relatively common for the traction control light to turn on along with the engine light when this happens, especially in Toyota Motor Corporation vehicles.

Common symptoms

DTC P0705 can cause some noticeable problems. 

Here are the more common ones:

• Vehicle may not start: Some cars have a neutral safety switch (or inhibitor switch), meaning they’ll only start in the ParkNeutral position for safety reasons. If the Transmission Range Switch sensor can’t accurately report the gear position, the vehicle may not start when you fire the ignition switch.
• Difficulty shifting gears: You may struggle to get your car in or out of gear. Gear changes may be rough or delayed.
• Reverse light isn’t illuminating: The reverse light may not activate if the ECM doesn’t receive input that the car is in reverse.
• Gear displays incorrectly: If your car has a gear indicator, it may not display the correct shift lever position.
• Check Engine Light is on: This indicates there’s an engine problem. A mechanic will be able to tell you if the trouble code is P0705.

Can I still drive?

It’s often not possible to drive with a P0705 code, though this may not always be the case.

Code P0705 will likely affect the vehicle’s ride quality. For example:

• The engine might not crank when you turn on the ignition switch (due to the neutral safety switch or inhibitor switch not getting the correct signals)
• You may experience erratic gear shifting, which could be dangerous
• The engine may stall more frequently
• The car may enter “limp mode” (or failsafe mode), limiting your speed to 40mph

Driving your car in this condition can cause serious damage to other engine parts. It’s recommended to take your vehicle to a mechanic ASAP.

P0705 causes

Many factors could cause DTC P0705, not just a faulty sensor. A mechanic should check for all of these potential faults:

• A short, torn harness, or frayed wire in the Transmission Range Sensor circuit
• A misadjusted ParkNeutral Position switch
• Misaligned wire harness connector at the shift linkage cables
• Old or dirty transmission fluid
• A fault in the transmission valve body

Diagnosis

To identify what code is causing the engine light, you can use an OBD II scanner. This will tell you if the problem is a P0705 Transmission Range Sensor Circuit malfunction.

However, finding the root cause of the error may require specialized knowledge and tools, so it’s best to take your car to a mechanic.

Here’s how a mechanic will diagnose code P0705:

• Identify the Transmission Range Sensor type: There are three types, each requiring a slightly different approach to repairs. The types are:
• Contact TRS: Each gear position has a separate wire to specify the position of the gear indicator.
• Pressure Range Sensor: The ParkNeutral Position sensor, positioned on the transmission valve body, opens and closes a different passage for each gear position. Transmission fluid flows through the open passage to indicate the selector lever position.
• Variable Resistor TRS: Each shift lever position has a different standard resistance. The effect on the current flowing through the system indicates the shift lever position.
• Inspect the tail light: Sometimes, humidity in the tail light can create shorts that cause the P0705 code. Check for cracks or signs of moisture.
• Check the transmission fluid: Ensure that the level and condition of the transmission fluid are as required.
• Ensure that the Transmission Range Switch is properly connected: The problem may be caused by a misaligned ParkNeutral Position Switch. Check the connector for misalignment.
• Test the voltage and ground at the TRS sensor: The mechanic can use a multimeter to test voltage output for each gear. The process is different for each of the three TRS types:
• Contact TRS: Measure the voltage on each wire while someone changes gears.
• Pressure Range Sensor: Measure the voltage on the reference wire. The voltage should be different for each selector lever gear position.
• Pressure Range Switch: Measure the change in voltage on the ground wire corresponding to each selector lever position. Use a wiring diagram to see which wire is which.
• Check for standard resistance if the voltage is found to be low (but not zero).
• Inspect the ParkNeutral Position switch circuit: If the voltage and ground seem sound, the mechanic will need to inspect the entire PNP switch circuit.

Check harness for frayed wires and look for breakages in the harness. Inspect the ParkNeutral Position switch circuit for blown fuses, a faulty wire harness connector, and anything that could disrupt the continuity in the wiring harness.

Your mechanic should perform each check correctly to avoid unnecessary expensive repairs. For example, they should properly inspect the wiring harness continuity, transmission fluid and connector alignment before diagnosing a faulty ParkNeutral Position switch or replacing any parts.

Possible repairs for P0705 & Costs

Fixing DTC P0705 may require repairing or replacing one or more of the following:

• Dirty transmission fluid (inexpensive but should be done regularly)
• Faulty Transmission Range Sensor circuit wiring (inexpensive but labor intensive)
• Linkage between the selection lever inside the car and the shift lever on the transmission (inexpensive but labor intensive)
• Misadjusted ParkNeutral Position Switch (inexpensive but labor intensive)
• Faulty ParkNeutral Position switch or TRS
• Faulty Transmission Control Module (expensive but uncommon)
• Faulty Engine Control Module (expensive but uncommon)

The cost of repairs will include parts and labor charges and may vary based on the make and model of the vehicle.

Here are some rough estimates:

• Replacing the TRS: $100-$350
• Adjusting the TRS connector: $100
• Repairing the ParkNeutral Position Switch harness or wiring: $100-$1000
• Repairing the tail light: $200-$2000 (depending on make and model)
• Repairing the valve body: $400-$1000
• Replacing the transmission: $1800-$4500