Advanced Diagnostics

Advanced Diagnostics - DTC P1890: Problem in CVT Speed Control System






General Description
The shift control system controls each gear position using a map stored in the powertrain control module (PCM) memory. The shift control system controls the CVT drive pulley pressure control solenoid valve and the CVT driven pulley pressure control solenoid valve according to the vehicle speed and the throttle position so the drive pulley speed becomes equal to the target value, i.e., it varies the hydraulic pressure applied to the drive and driven pulley and provides feedback on the difference between the target drive pulley speed and the actual drive pulley speed when driving. It supplies high hydraulic pressure to the driven pulley and enlarges the driven pulley belt diameter when shifting to a lower ratio. It supplies high hydraulic pressure to the drive pulley and enlarges the drive pulley belt diameter when shifting to a higher ratio. If the difference between the target drive pulley speed and the actual drive pulley speed is specified value when in D, S, L, or R, the PCM detects a malfunction in the CVT shift function and stores a DTC.

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






Enable Conditions






Malfunction Threshold
The difference between the target drive pulley speed and the actual drive pulley speed is 500 rpm or more for at least 18 seconds.

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