P2707

Shift Solenoid F Perf or Stuck Off

Indicator

This code indicates that the PCM has detected a transmission friction element application malfunction. When this occurs, a code is stored and a malfunction indicator lamp may be illuminated. Some vehicles will also enter "limp-in" mode.

Code Set Parameters

When the output RPM signal is not within an acceptable range (compared to the input RPM signal) the PCM may recognize it as a transmission friction element application malfunction. This type of condition is comparable to a transmission component slippage condition and as such a transmission slippage code may accompany this code.

Symptoms

The service engine soon lamp is usually accompanied by transmission slippage or lack of transmission engagement. Harsh shifting, caused by the transmission control system entering limp in mode, is also possible.

Common Causes

Common causes include a faulty or slipping transmission caused by a low transmission fluid condition, a transmission fluid leak, a faulty transmission pump, overheating engine, defective input or output speed sensors, or a faulty PCM. System wiring, connectors, or other electrical components are also subject to failure. When this code is set, it is imperative that the transmission be checked prior to further vehicle operation.

Common Misdiagnosis

Misdiagnosis may range from one extreme to the other. Often, when this code is stored, a problem is incorrectly diagnosed as only a transmission fluid leak when a low fluid condition has allowed vital internal transmission components to be damaged. On the other end, the transmission does not necessarily need to be rebuilt just because it has overheated once.

Diagnosis

  • Most OBD-II equipped automobiles utilize an input/turbine speed sensor to provide the PCM with an input speed signal
  • On most models the sensor either threads directly into the transmission housing or is mounted to the exterior of the transmission housing using bolts
  • The sensor is of the electro magnetic design and uses a reluctor ring (or a specialized set of splines) on the input shaft as reference points
  • As the input shaft is turned (by the engine) the electro magnetic input/turbine speed sensor uses the spaces between the splines to provide voltage signal interruptions in the circuit
  • These interruptions are received by the PCM as square waveform patterns of varying degrees of voltage and translated into engine (turbine) input speed
  • The PCM then compares input speed data with output speed data to determine shift patterns, as well as certain engine drivability functions. The typical input/turbine speed sensor uses a three-wire connector but check the vehicle manufacturer's wiring diagram to confirm the specific design of the vehicle in question
  • The first wire is a reference voltage signal (usually 5-volts), the second wire will normally be a ground wire, and the third wire will be a signal wire
  • As the reluctor ring passes by the electro magnetic sensor, the 5-volt reference signal is completed with the protruding metal surfaces
  • The recessed surfaces of the reluctor provide voltage interruptions and these interruptions are input to the PCM via the signal wire
  • An output speed sensor is used to provide the PCM with a transmission output speed signal
  • On most models the sensor either threads directly into the transmission housing or is mounted to the exterior of the transmission housing using bolts
  • The sensor is of the electro magnetic design and uses a reluctor ring (or a specialized set of splines) on the output shaft as reference points
  • As the output shaft is turned (by the engine) the electro magnetic output speed sensor uses the spaces between the splines to provide voltage signal interruptions in the circuit
  • These interruptions are received by the PCM as square waveform patterns of varying degrees of voltage and translated into transmission output speed
  • The PCM then compares transmission output speed data with engine input speed data to determine shift patterns, as well as certain engine drivability functions. The typical output speed sensor uses a three-wire connector but check the vehicle manufacturer's wiring diagram to confirm the specific design of the vehicle in question
  • The first wire is a reference voltage signal (usually 5-volts), the second wire will normally be a ground wire, and the third wire will be a signal wire
  • As the reluctor ring passes by the electro magnetic sensor, the 5-volt reference signal is completed with the protruding metal surfaces
  • The recessed surfaces of the reluctor provide voltage interruptions and these interruptions are input to the PCM via the signal wire
  • Begin your diagnosis with a visual inspection of system wiring, connectors, and components
  • Repair or replace any open, shorted, damaged, or corroded items as required and retest the system to make sure that repairs were successful
  • Pay particular attention to wiring and connectors that have been contaminated due to engine oil or transmission fluid leaks, burned on hot exhaust pipes, or damaged due to road debris. Inconsistencies between the input and output speed sensor readings may be interpreted by the PCM as a transmission friction element application malfunction
  • 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 reference voltage and ground signals at the input/output speed sensors
  • If either the reference voltage or ground 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 input/output speed sensor, test all related circuits and sensors 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 clear codes and retest the system to ensure a successful repair has been performed. If all system circuits are intact, connect the oscilloscope and observe live transmission input/output speed sensor data
  • Observe the wave form pattern (for glitches or "soft spots") and repair or replace system circuitry, connectors, or components as required. If a transmission over temp code is also set and the engine is not overheating, then it is very likely that a low or substandard transmission fluid condition is present
  • To perform a thorough diagnosis, any transmission leaks should be repaired and the transmission should be filled with the proper amount and type of fluid (if the fluid smells really "burnt" and you are experienced enough to detect it, you may go ahead and condemn the transmission)
  • The transmission should then be operated normally and rechecked
  • However, leaks that originate from the front seal (behind the torque converter) will likely require removal of the transmission, at which time you may want to consider a transmission rebuild if the mileage dictates. If the transmission appears to be in good working order and doesn't appear to be overheating, suspect a defective input or output speed sensor
  • Should all system circuitry and sensors check out and the transmission is in good working order, suspect a faulty PCM but keep in mind that PCM failure is rare and PCM replacement will require reprogramming.