Follow this Real Fix to see how to diagnose a P0715 code and test the transmission speed sensors on this 1999 Mercedes-Benz C280.
Vehicle
1999 Mercedes-Benz C280 2.8
Title
P0715, Replaced transmission input shaft speed sensor, transmission speed sensor
Complaint
The customer states the check engine light is on.
Cause
Connected a scan tool and found code P0715 – Input/Turbine Speed Sensor “A” Circuit. Connected a scan tool and checked value of turbine speed sensor, found value to be implausible. Performed a visual inspection of the transmission control module (TCM) connector, and wiring harness and found no apparent faults. Key on, backprobed the TCM connector with the multi-meter, measured the specified 6.0 Volt terminal #13 reference, less than 100mv ground terminal #33 and found both were present. Engine running, used the lab scope, backprobed the TCM terminal #12 and observed waveform signature integrity specified frequency of 730 Hz to 750 Hz at idle and 2.5 Hz at 2500 RPM. The lab scope did not produce an observable signal during the test. The results of these tests verified the transmission input shaft speed sensor and the transmission speed sensor were faulty. Sensors for the turbine speed and transmission speed are integrated into the electrical conductor plate on top of the valve body in the transmission and are replaced as an entire unit.
Correction
Replaced the transmission input shaft speed sensor and transmission speed sensor, cleared codes, performed a road test and verified the vehicle operated properly. The check engine light did not illuminate and no fault codes returned.
SureTrack® is a powerful value-added feature available with select Snap-on diagnostics tools. It offers an exclusive combination of expert knowledge and detailed parts replacement records, all wrapped in an interactive community.
Want more? Click here for more information on using SureTrack.
Looking for diagnostic tools? Click here to request more information on Snap-on diagnostic tools.
New or Expired SureTrack users: Click here for authorization key instructions.
