P0846

P0846-2/4 PRESSURE SWITCH RATIONALITY





For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Transmission system uses three pressure switches to monitor the fluid pressure in the LR, 2/4, and OD elements. The pressure switches are continuously monitored for the correct states in each gear. The 2/4 pressure switch monitors the fluid pressure to the 2/4 clutch to confirm proper operation of the 2/4 solenoid. If the 2/4 pressure switch is identified as closed in P or N, the code will immediately be set and normal operation will be allowed for that given key start. If the problem is identified for 3 successive ignition cycles, the transmission will go into limp-in mode.

- When Monitored:
Whenever the engine is running.

- Set Condition:
The DTC is set if one of the pressure switches are open or closed at the wrong time in a given gear. If the problem is identified for 3 successive key starts, the transmission will go into limp-in mode and the MIL will turn on after 10 seconds of vehicle operation.





Always perform the 42RLE Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview.

PRESSURE SWITCH STATES






1. CHECK FOR RELATED DTCS
1. Using the scan tool, read TIPM DTCs.

Are there any TIPM TCM Power Control Circuit DTCs present also?

Yes

- Refer to DTC Based Diagnostics and perform the appropriate diagnostic procedure.

No

- Go To 2

2. CHECK FOR LOSS OF PRIME DTC
1. Using the scan tool, read DTCs.

Is the DTC P0944 present also?

Yes

- Refer to DTC Based Diagnostics and perform the appropriate diagnostic procedure.

No

- Go To 3

3. CHECK IF THE DTC IS CURRENT
1. Using the scan tool, read DTCs.

Is the status Active or is the Starts Since Set counter 2 or less for this DTC?

Yes

- Go To 4

No

- Go To 8

4. CHECK THE PCM AND WIRING USING THE TRANSMISSION SIMULATOR
1. Turn the ignition off to the lock position.
2. Remove the Starter Solenoid Relay from the TIPM.

CAUTION: Removal of the Starter Solenoid Relay from the TIPM will prevent the vehicle from being started in gear.

WARNING: The Starter Solenoid Relay must be removed from the TIPM. Failure to do so can result in possible serious or fatal injury.

3. Install the Transmission Simulator 8333 and the Electronic Transmission Adapter kit.
4. Ignition on, engine not running.
5. With the Transmission Simulator, turn the Pressure Switch selector to 2/4.
6. Using the scan tool, monitor the 2/4 Pressure Switch state while pressing the Pressure Switch Test button on the Transmission Simulator.

Did the 2/4 Pressure Switch state change?

Yes

- Replace the Transmission Solenoid/Pressure Switch Assembly.
- Perform the 42RLE TRANSMISSION VERIFICATION TEST. Transmission Verification Test.

No

- Go To 5

5. CHECK THE (T47) 2/4 PRESSURE SIGNAL CIRCUIT FOR AN OPEN




1. Turn the ignition off to the lock position.
2. Disconnect the PCM C4 harness connector.
3. Disconnect the Transmission Solenoid/Pressure Switch Assembly harness connector.

NOTE: Check connectors - Clean/repair as necessary.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install the PCM Pinout Box 8815 to perform diagnosis.

4. Measure the resistance of the (T47) 2/4 Pressure Signal circuit between the Transmission Solenoid/Pressure Switch Assembly harness connector and the appropriate terminal of the PCM Pinout Box 8815.

Is the resistance above 5.0 Ohms?

Yes

- Repair the (T47) 2/4 Pressure Signal circuit for an open.
- Perform the 42RLE TRANSMISSION VERIFICATION TEST. Transmission Verification Test.

No

- Go To 6

6. CHECK THE (T47) 2/4 PRESSURE SIGNAL CIRCUIT FOR A SHORT TO GROUND




1. Measure the resistance between ground and the (T47) 2/4 Pressure Signal circuit.

Is the resistance below 5.0 Ohms?

Yes

- Repair the (T47) 2/4 Pressure Signal circuit for a short to ground.
- Perform the 42RLE TRANSMISSION VERIFICATION TEST. Transmission Verification Test.

No

- Go To 7

7. CHECK THE (T47) 2/4 PRESSURE SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE




1. Ignition on, engine not running.
2. With the scan tool under TIPM, actuate the Transmission.
3. Measure the voltage of the (T47) 2/4 Pressure Signal circuit.

Is the voltage above 0.5 of a Volt?

Yes

- Repair the (T47) 2/4 Pressure Signal circuit for a short to voltage.
- Perform the 42RLE TRANSMISSION VERIFICATION TEST. Transmission Verification Test.

No

- Using the schematics as a guide, check the Powertrain Control Module (PCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace and program the PCM. Using the scan tool, perform Quick Learn. Quick Learn Procedure
- Perform 42RLE TRANSMISSION VERIFICATION TEST. Transmission Verification Test.

8. CHECK THE WIRING AND CONNECTORS
1. The conditions necessary to set the DTC are not present at this time.
2. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
3. Wiggle the wires while checking for shorted and open circuits.
4. Using the scan tool, check the Event Data to help identify the conditions in which the DTC was set.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the 42RLE TRANSMISSION VERIFICATION TEST. Transmission Verification Test.

No

- Test Complete.