P1842

DTC P1842 (3.0L)

Circuit Description
The 1-2 Shift Solenoid (SS) valve controls transmission fluid pressure acting on the 1-2 and 2-3 shift valves to position the valves for the appropriate gear. The 1-2 SS valve is a normally open exhaust valve located on the control valve body. The Transmission Control Module (TCM) provides voltage to the pressure control solenoid, the shift solenoids, and the TCC PWM solenoid through 2 separate solid-state devices called High Side Drivers (HSD) - HSD1 and HSD2. HSD1 provides electrical power to the pressure control solenoid. HSD2 provides electrical power to the shift solenoids, and the TCC PWM solenoid. The TCM then commands the solenoid ON or OFF by also providing a ground path. When the 1-2 SS valve is commanded ON, the TCM senses low voltage. When the 1-2 SS valve is commanded OFF, the TCM senses high voltage.

If the TCM detects a continuous open or short to ground in the 1-2 SS valve circuit, DTC P1842 sets. DTC P1842 is a type A DTC.

Conditions for Running the DTC
The engine run time is greater than 5 seconds.

Conditions for Setting the DTC
The 1-2 SS valve feedback circuit indicates a continuous open or short to ground for 4.3 seconds.

Action Taken When the DTC Sets
^ The TCM requests the ECM to illuminate the Malfunction Indicator Lamp (MIL).
^ The TCM commands maximum line pressure.
^ The TCM inhibits 3-2 downshifts above 52 km/h (32 mph).
^ The TCM freezes transmission adaptive functions.
^ The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as Freeze Frame and Failure Records.
^ The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
^ The TCM stores DTC P1842 in TCM history.

Conditions for Clearing the MIL/DTC
^ The ECM turns OFF the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request.
^ A scan tool can clear the MIL/DTC.
^ The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
^ The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

Test Description
The numbers below refer to the step numbers on the diagnostic table.
5. This step tests the electrical operation of the solenoid.
6. This step tests the TCM and the wiring to the transmission.
10. This step verifies that the circuit has the correct resistance.

Steps 1 - 5:

Steps 6 - 13:

Steps 14 - 20:

DTC P1842 (3.0L)