Powertrain Controls - ECM/PCM

DTC 56 Chart:

Turbine Shaft Speed (TSS) Sensor Circuit:

CIRCUIT DESCRIPTION
The Turbine Shaft Sensor (TSS) sensor circuit consists of a permanent magnet surrounded by a coil of wire. The TSS is mounted inside the transaxle case cover facing the drive sprocket of the input shaft. As the drive sprocket rotates, an AC voltage signal is induced and transmitted to the PCM.

DTC 56 WILL SET WHEN
- No DTC(s) 24, 75, 91.
- Transaxle not in park/neutral.
- Engine running.
- Vehicle speed 10 mph or greater.
- Turbine speed 50 RPM or less.
- All conditions met for 2 seconds.

ACTION TAKEN (PCM WILL DEFAULT TO)
- With a current DTC 56 set, the PCM will illuminate the Malfunction Indicator Lamp (MIL) (Service Engine Soon).
- The PCM calculates the transaxle input speed based on the output speed and the gear ratio of the commanded gear.
- The PCM calculates slip speed from the calculated input speed and engine RPM.
- Torque converter clutch (TCC) engaged.

DTC 56 WILL CLEAR WHEN
The fault no longer exists.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.

1. This test checks for an AC voltage signal from the sensor.
2. This test checks the wiring from the sensor to the transaxle connector.

DIAGNOSTIC AIDS
This diagnostic test checks for an input speed sensor circuit problem. If the the engine is running and the vehicle is moving above a certain speed then the input speed must be non-zero. The DTC is set if the turbine speed is less than a certain threshold. Check all connections for good contact.