Transmission Range Sensor Circuit High Input
The PCM has detected a malfunction in the transmission shift mechanism range circuit. The transmission range sensor inputs data to the PCM where it is utilized to calculate engine RPM, fuel delivery strategy, and engine timing, among other things. This code applies to vehicles equipped with an automatic transmission only.
Code Set Parameters
If the PCM receives inputs from the vehicle speed sensor, transmission shift solenoids, torque converter lock-up solenoid, or other sensors, indicating that the vehicle is being operated in an incorrect transmission shifter range a code will be stored and a malfunction indicator lamp may be illuminated. The transmission may also be placed in limp-in mode by the PCM.
Symptoms may include harsh shifting, failure to shift, reduced fuel efficiency, service engine soon lamp illumination, and a stored code.
By far the most common cause of this code is from a misadjusted transmission range sensor. Other causes may include a defective range sensor, open, shorted, corroded, or otherwise damaged wiring and/or electrical connectors. If recent transmission repairs have been performed, suspect that the range sensor was not readjusted properly. Sensor retaining bolts should always be installed using thread locking compound to ensure proper torque longevity. Technicians also report the presence of excessive corrosion in the sensor connector as the cause of this code being stored.
The transmission range sensor is frequently replaced in error when a simple adjustment will correct the complaint.
- The transmission range sensor is used to determine (for the PCM) which gear the transmission is placed in, as well as acting as a neutral safety switch for engine ignition
Most transmission range sensors (so called almost exclusively on Ford models) are of a variable resistance variety
- The switch is positioned over the transmission shift shaft and the shift lever slides over it
- As the shift lever is moved (via the shifter in the cockpit and the shifter cable) the range sensor pivot is moved to different contacts
- The PCM reads the varying levels of voltage, regulated by the differing levels of resistance in the switch contacts, as the gears in which the transmission shifter are placed
- The PCM then determines shift strategy, fuel delivery theory, engine ignition timing, and other drivability functions accordingly
- As transmission, ABS, and engine inputs are received by the PCM, it determines whether or not the transmission is in the correct gear for driving conditions and reacts accordingly.
There are several tools which will be instrumental in attempting to successfully diagnose the conditions which contribute to this code being stored
- A suitable OBD-II scanner (or code reader) and a digital volt/ohmmeter will be most helpful in trying to perform a successful diagnosis
- Gaining access to access a manufacturer’s wiring schematic will also prove to be necessary to successfully diagnosing this code.
Perform a careful visual inspection of all PCM wiring and connectors
- Repair or replace damaged, disconnected, shorted, or corroded wiring, connectors, and components as necessary
- Always retest the system after repairs are completed to ensure success.
If all system wiring, connectors, and components (Including fuses) appear to be in normal working order, connect the scanner (or code reader) to the diagnostic connector and record all stored codes and freeze frame data
- This information can be extremely helpful in diagnosing intermittent conditions that may have contributed to this code being stored
- Continue by clearing the code and operating the vehicle to see if it returns
- This will help to determine whether or not the malfunction is intermittent.
After the codes are cleared, test drive the vehicle to see if the code returns
- If the code fails to immediately return, you may have an intermittent condition
- Intermittent conditions can prove to be quite a challenge to diagnose and in extreme cases may have to be allowed to worsen before a correct diagnosis can even be attempted
If the code immediately returns, check for battery voltage and ground signals at the transmission range sensor
- If either the ground or battery voltage circuits are open, use the digital volt/ohmmeter to check for continuity (disconnect all related control modules from the circuit before checking circuit resistance or controller damage may occur) and resistance in both circuits
- Repair or replace system circuits/connectors as required and retest the system to ensure that repairs were successful.
Using the manufacturer’s wiring diagram for the transmission range sensor, test all related circuits and the sensor for resistance and continuity and compare your findings with manufacturer’s specifications
- Repair or replace system circuitry, connectors, and/or components that fail to coincide with manufacturer’s specs
- Always retest the system to ensure a successful repair.
If all circuits coincide with manufacturer’s specifications, suspect a defective PCM
- Remember that PCM failure is rare and replacement will require reprogramming