Advanced Diagnostics

Advanced Diagnostics - DTC P1891: Start Clutch Control System











General Description
The start clutch control system controls the clutch piston hydraulic pressure that affects the amount of power transmitted by the multiplate wet start clutch on the driven pulley shaft. The powertrain control module (PCM) activates the CVT start clutch pressure control solenoid valve to control the hydraulic pressure that is applied to the start clutch piston in accordance with vehicle conditions. The start clutch control system detects clutch overslip. If the difference between the vehicle speed measured by the CVT output shaft (driven pulley) speed sensor and the one measured by the vehicle speed sensor is excessive when driving the vehicle under the Enable Conditions, the PCM detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status






Enable Conditions






Malfunction Threshold
The deviation in the vehicle speed measured by the vehicle speed sensor and vehicle speed measured by the CVT output shaft (driven pulley) speed sensor is in the Failure Area shown in Graph 2 for at least 10 seconds.

Driving Pattern
1. Start the engine.
2. Accelerate gradually to 38 mph (60 km/h) and drive at least 1 minute at 38 mph (60 km/h).

- Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.

Diagnosis Details

Conditions for setting the DTC
When a malfunction is detected, the D indicator blinks, and a Pending DTC, a Confirmed DTC, and the freeze data are stored in the PCM memory. The MIL does not come on.

Conditions for clearing the DTC
The Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the battery.