P084B

P084B-DC PRESSURE SWITCH RATIONALITY





For a complete wiring diagram Consult Diagrams/Electrical.

Theory of Operation

The Transmission system uses five pressure switches to monitor the fluid pressure in the LR, 2/4, OD, LC and DC elements. The pressure switches are continuously monitored for the correct states in each gear. The DC pressure switch monitors the fluid pressure to the DC clutch to confirm proper operation of the DC solenoid. If the DC 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 62TE Pre-Diagnostic Troubleshooting procedure before proceeding.Testing and Inspection





Diagnostic Test

1. CHECK IF RELATED TCM DTCS ARE PRESENT
With the scan tool, read DTCs
Are there any TCM Power Input DTCs present also?

Yes

- Diagnose and repair the DTC(s).

No

- Go to 2

2. CHECK FOR LOSS OF PRIME DTC
With the scan tool, read DTCs.
Is the DTC P0944 present also?

Yes

- Diagnose and repair the DTC(s).

No

- Go to 3

3. CHECK IF DTC P084B IS CURRENT
With the scan tool, read DTCs.
Is the status Active for this DTC or is the STARTS SINCE SET counter 2 or less?

Yes

- Go to 4

No

- Go to 8

4. PCM AND WIRING
Turn the ignition off to the lock position.
Remove the Ignition Switch Feed fuse from the TIPM.

CAUTION: Removal of the Ignition Switch Feed fuse from the TIPM will prevent the vehicle from being started in gear.

WARNING: The Ignition Switch Feed fuse must be removed from the TIPM. Failure to do so can result in personal injury or death.

Install the Transmission Simulator, Miller tool #8333 and the Electronic Transmission Adapter kit.

NOTE: Check connectors - Clean/repair as necessary.

Ignition on, engine not running.
With the Transmission Simulator, turn the Pressure Switch selector to DC.
With the scan tool, monitor the DC Pressure Switch state while pressing the Pressure Switch Test button on the Transmission Simulator.
Did the DC Pressure Switch state change?

Yes

- Replace the Transmission Solenoid/TRS Assembly.
- Perform 62TE VERIFICATION TEST Transmission Verification Test

No

- Go to 5

5. (T83) DC PRESSURE SIGNAL CIRCUIT OPEN




Turn the ignition off to the lock position.
Disconnect the PCM C4 harness connector.
Disconnect the Transmission Solenoid/TRS Assembly harness connector.

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 Miller Special Tool #8815 to perform diagnosis.

Measure the resistance of the (T83) DC Pressure Signal circuit between the appropriate terminal of the Miller tool #8815 and the Transmission Solenoid/TRS Assembly harness connector.
Is the resistance above 5.0 ohms?

Yes

- Repair the (T83) DC Pressure Signal circuit for an open.
- Perform 62TE VERIFICATION TEST Transmission Verification Test

No

- Go to 6

6. (T83) DC PRESSURE SIGNAL CIRCUIT SHORT TO GROUND




Measure the resistance between ground and the (T83) DC Pressure Signal circuit.
Is the resistance below 5.0 ohms?

Yes

- Repair the (T83) DC Pressure Signal circuit for a short to ground.
- Perform 62TE VERIFICATION TEST Transmission Verification Test

No

- Go to 7

7. (T83) DC PRESSURE SIGNAL CIRCUIT SHORT TO VOLTAGE




Ignition on, engine not running.
With the scan tool in the TIPM, actuate the TCM output.
Measure the voltage of the (T83) DC Pressure Signal circuit.
Is the voltage above 0.5 volts?

Yes

- Repair the (T83) DC Pressure Signal circuit for a short to voltage.
- Perform 62TE VERIFICATION TEST Transmission Verification Test

No

- Replace and program the Powertrain Control Module. With the scan tool perform QUICK LEARN.
- Perform 62TE VERIFICATION TEST Transmission Verification Test

8. INTERMITTENT WIRING AND CONNECTORS
The conditions necessary to set the DTC are not present at this time.
Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
Wiggle the wires while checking for shorted and open circuits.
With the scan tool, check the DTC EVENT DATA to help identify the conditions in which the DTC was set.
Were there any problems found?

Yes

- Repair as necessary.
- Perform 62TE VERIFICATION TEST Transmission Verification Test

No

- Test Complete.