Advanced Diagnostics

Advanced Diagnostics - DTC P1860: Inhibitor Solenoid Circuit Low Voltage






General Description
The inhibitor solenoid controls the oil pressure supply to the forward clutch and the reverse brake through a reverse inhibitor valve. When the transmission gear selector is shifted to the R position mistakenly during forward driving at speed, it controls the inhibitor solenoid to intercept the activation of the reverse brake because there is a possibility of damaging the transmission. The inhibitor solenoid is driven by a driver circuit according to the command from the powertrain control module (PCM). This driver circuit is equipped with a diagnosis function to detect an open or a short circuit, and sends back a return signal to the PCM. When the return signal is inappropriate for the PCM command, the PCM detects a malfunction and stores a DTC.

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






Enable Conditions






Malfunction Threshold
The return signal is inappropriate for the turn on command to the inhibitor solenoid.

Confirmation Procedure with the HDS
Do the Inhibitor Solenoid Test in the Miscellaneous Test Menu with the HDS.

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.