Technical Description of OBD-II Trouble Code
Circuit for Input/Turbine Speed Sensor A
This diagnostic trouble code (DTC) is a generic powertrain code that is applicable to all vehicles manufactured in 1996 or later (such as Ford, Honda, Mazda, Mercedes, VW, etc.). While it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
What does this mean?
Whenever I have come across a diagnostic trouble code P0715, it has been because the powertrain control module (PCM) has detected a malfunction in the circuit for the designated input (or turbine) speed sensor known as A. The input and turbine speed sensors have virtually identical designs, with the difference primarily lying in the descriptive terminology. The A designation is typically used for OBD-II equipped vehicles that utilize multiple input or turbine speed sensors. To locate the input/turbine sensor designated A, refer to the manufacturer’s service manual.
The input/turbine speed sensor is typically an electromagnetic, 3-wire sensor that is used to monitor the transmission’s input speed, which is recognized by the PCM as revolutions per minute (RPMs). The sensor is positioned near the rear of the torque converter, at the transmission input shaft, and is either mounted with a bolt/stud or threaded directly into the transmission case.
On the transmission’s main (or input) shaft, there are specially designed grooves (or a notched reluctor wheel). The input shaft (or reluctor wheel) passes in close proximity to the end of the sensor, completing the electromagnetic circuit. As the grooves (or notches) pass by the sensor, the circuit is interrupted and an electronic pattern is formed. The PCM receives this pattern formation as a waveform pattern, which it further interprets as the transmission’s input/turbine speed.
The transmission’s input/turbine speed is compared with the engine’s RPM speed, percentage of engine load, transmission output speed, and vehicle speed in order to determine the desired input speed RPM. If the actual input/turbine speed does not coincide with the desired input/turbine speed, a code will be stored and a malfunction lamp may be illuminated.
Symptoms & Severity
In some cases, the storage of this code will prompt the PCM to place the transmission in ‘limp-in’ mode, resulting in harsh shifting. If you encounter a P0715 code and notice irregular shifting of the transmission, it is important to address the problem as soon as possible.
Symptoms of a P0715 code may include:
Causes
Potential causes for the occurrence of this code are:
Diagnostic and Repair Procedures
A good starting point is to always check for technical service bulletins (TSB) specific to your vehicle. Your issue may be a known problem with a known solution provided by the manufacturer, which can save you time and money during the diagnosis process.
In diagnosing the P0715 code, it is helpful to have a suitable diagnostic scanner, a digital volt/ohmmeter (DVOM), a system wiring diagram, and possibly an oscilloscope.
Skilled technicians typically begin by visually inspecting the system wiring and connectors. Any disconnected, corroded, burnt, or shorted parts should be repaired or replaced as necessary. The battery should be tested and the battery cables and cable ends should be inspected. Corrosion should be removed and battery terminals should be securely fastened as required.
Connect the scanner to the diagnostic port and retrieve all stored codes. Make a note of all stored codes for future reference. If available, freeze frame data should also be noted.
If both input sensor and output sensor codes are present, use the scanner data stream to determine which circuit is malfunctioning. Narrow down the data stream to include only related data for more responsive data delivery.
When removing sensors, check for excessive metal debris on the magnetic contacts. Remove any excessive debris before reinstalling the sensors. When the sensors are removed, inspect the interruption grooves and/or reluctor wheel notches. Test each sensor individually using the DVOM and follow the manufacturer’s specifications (found in the service manual or through All Data). Replace any sensors that fail to comply with the specifications.
Before testing resistance and continuity with the DVOM, disconnect any related controllers. Failure to do so could result in damage to the controllers. Test the system circuits for shorted or open wiring, and repair or replace any defective circuits. If all system circuits and sensors are functioning properly, suspect a faulty PCM or a PCM programming error.
Additional diagnostic notes:
