P1845

Circuit Description with 4T80-E Automatic Transaxle

Schematic:

The 2-3 Shift Solenoid (2-3 SS) valve controls the transmission fluid pressure acting on the 1-2 and 2-3 shift valves to position the valves for the appropriate gear. The 2-3 SS valve is a normally open exhaust valve located on the lower control valve body. Ignition voltage is supplied to the solenoid. The Output Driver Module (ODM), within the PCM, commands the solenoid ON or OFF by providing a ground path. When the 2-3 SS valve is commanded ON, the PCM senses low voltage. When the 2-3 SS valve is commanded OFF, the PCM senses high voltage.

If the PCM detects a continuous open or short to ground in the 2-3 SS valve circuit, then DTC P1845 sets. DTC P1845 is a type A DTC.

CONDITIONS FOR RUNNING THE DTC
^ The system voltage is 8-18 volts.
^ The engine run time is greater than 5 seconds.
^ The engine is not in fuel cut off.

CONDITIONS FOR SETTING THE DTC
The 2-3 SS valve feedback circuit indicates a continuous open or short to ground for 4.3 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM illuminates the Malfunction Indicator Lamp (MIL).
^ The PCM commands an immediate landing to 2nd gear.
^ The PCM commands maximum line pressure.
^ The PCM inhibits TCC engagement.
^ The PCM freezes transmission adapt functions.
^ The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.
^ The PCM stores DTC P1845 in PCM history.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
^ A scan tool can clear the MIL/DTC.
^ The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
^ The PCM cancels the DTC default actions when the fault no longer exists and/or the ignition switch is OFF long enough in order to power down the PCM.

DIAGNOSTIC AIDS
^ Inspect the connectors at the PCM, the 2-3 SS valve and all other circuit connecting points for an intermittent condition. Refer to Testing for Intermittent and Poor Connections in Diagrams.
^ Inspect the circuit wiring for an intermittent condition. Refer to Testing for Electrical Intermittents in Diagrams.
^ Refer to Shift Solenoid Valve State and Gear Ratio table.

TEST DESCRIPTION

Steps 1 - 4:

Steps 5 - 13:

Steps 14 - 22:

The numbers below refer to the step numbers on the diagnostic table.
8. This step tests the electrical operation of the solenoid.
9. This step verifies the PCMs ability to command the solenoid.
17. This step verifies that the circuit has the correct resistance.