40/41TE Automatic Transaxle (GPEC)

P0841-LR PRESSURE SWITCH RATIONALITY





For a complete wiring diagram Consult Diagrams/Electrical.

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. If a set condition is identified, 1st gear and torque converter lock-up (EMCC) will be inhibited. The vehicle will launch in 2nd gear and shift normally through the gears without allowing EMCC. If during the same ignition start, the set condition is no longer valid, the transmission will return to normal operation (1st and EMCC available). Limp-in will not occur unless DTC P0841 is accompanied by a code P0706 and the MIL will illuminate after 5 minutes of substituted operation.

- 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 ignition starts, the transmission will go into Limp-in mode and the MIL will turn on after 10 seconds of vehicle operation.





Always perform the 40/41TE Pre-Diagnostic Troubleshooting procedure before proceeding. Testing and Inspection





Diagnostic Test

1. CHECK FOR RELATED DTCS
With the scan tool, read Transmission DTCs.
Are there any Transmission Control Relay or TCM Power Input DTCs present also?

Yes

- Diagnose and repair the DTC(s).

No

- Go to 2

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

Yes

- Diagnose and repair the DTC(s).

No

- Go to 3

3. CHECK IF THE DTC IS CURRENT
With the scan tool, read Transmission 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. CHECK THE PCM AND WIRING WITH THE TRANSMISSION SIMULATOR
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 L/R.
With the scan tool, monitor the L/R Pressure Switch state while pressing the Pressure Switch Test button on the Transmission Simulator.
Did the L/R Pressure Switch state change?

Yes

- Replace the Transmission Solenoid/Pressure Switch Assembly.
- Perform 40/41TE VERIFICATION TEST 40/41TE Transmission Verification Test

No

- Go to 5

5. CHECK THE (T50) L/R PRESSURE SIGNAL CIRCUIT FOR AN OPEN




Turn the ignition off to the lock position.
Disconnect the PCM C2 harness connector.
Disconnect the Transmission Simulator, Miller tool #8333 and the Electronic Transmission Adapter kit.
Measure the resistance of the (T50) L/R Pressure Signal circuit between the PCM C2 harness connector and the Transmission Solenoid/Pressure Switch Assembly harness connector.
Is the resistance above 5.0 ohms?

Yes

- Repair the (T50) L/R Pressure Signal circuit for an open.
- Perform 40/41TE VERIFICATION TEST 40/41TE Transmission Verification Test

No

- Go to 6

6. CHECK THE (T50) L/R PRESSURE SIGNAL CIRCUIT FOR A SHORT TO GROUND




Measure the resistance between ground and the (T50) L/R Pressure Signal circuit.
Is the resistance below 5.0 ohms?

Yes

- Repair the (T50) L/R Pressure Signal circuit for a short to ground.
- Perform 40/41TE VERIFICATION TEST 40/41TE Transmission Verification Test

No

- Go to 7

7. CHECK THE (T50) L/R PRESSURE SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE




Ignition on, engine not running.
With the scan tool in the TIPM, actuate the TCM output.
Measure the voltage of the (T50) L/R Pressure Signal circuit.
Is the voltage above 0.5 volts?

Yes

- Repair the (T50) L/R Pressure Signal circuit for a short to voltage.
- Perform 40/41TE VERIFICATION TEST 40/41TE 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. Check for Service Information Tune-ups or Service Bulletins for any possible causes that may apply. If no problems are found, replace and program the PCM. With the scan tool, perform QUICK LEARN.
- Perform 40/41TE VERIFICATION TEST 40/41TE Transmission Verification Test

8. CHECK THE 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 40/41TE VERIFICATION TEST 40/41TE Transmission Verification Test

No

- Test Complete.