P0992

P0992-2/4/OD HYDRAULIC PRESSURE TEST



Theory of Operation

Pressure switches are normally off or open (no pressure applied) and read high (+12 volts). When an element is applied, the corresponding pressure switch closes to ground (0 volts) or turns on. The controller tests the OD and 2/4 pressure switches when they are off (when the corresponding friction element is not applied) by briefly applying the OD and 2/4 elements which will cause the corresponding pressure switch to close. The test verifies that the switches are operational and that the switch will close when the corresponding element is applied. If a switch fails to respond, it is retested. If the repeat test also fails, the MIL illuminates and the transmission system defaults to Limpin mode.

- When Monitored:
In any forward gear with engine speed above 1000 RPM, shortly after a shift and every minute thereafter.

- Set Condition:
After a shift into a forward gear, with engine speed greater than 1000 RPM, the Powertrain Control Module (PCM) momentarily turns on element pressure to the clutch circuits that do not have pressure to identify that the correct pressure switch closes. If the pressure switch does not close two times the DTC sets.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.
CHECK TO SEE IF DTC P0992 IS CURRENT

NOTE: The vehicle must be driven to set this DTC. The transmission must be at normal operating temperature with the Engine RPM above 1000 RPM.

1. This DTC is an indication of both the 2/4 and the O/D Hydraulic Pressure Switch DTCs are present.
2. Perform the diagnostic procedures for both P0845 P0845 and P0870 P0870.
3. With the scan tool, check the Event Data to help identify the conditions in which the DTC was set.

Repair

- Perform the diagnostic procedures for P0845 P0845 and P0870 P0870.
- Perform the appropriate TRANSMISSION VERIFICATION TEST. .