40/41TE Automatic Transaxle (GPEC)
P0845-2/4 HYDRAULIC PRESSURE TEST
For a complete wiring diagram Consult Diagrams/Electrical.
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 re-tested. The MIL illuminates and the transmission system defaults to Limp-in 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 PCM momentarily turns on element pressure to the clutch circuits that don't have pressure to verify that the correct pressure switch closes. If the pressure switch does not close 2 times the DTC sets
Always perform the 40/41TE Pre-Diagnostic Troubleshooting procedure before proceeding. Testing and Inspection
Diagnostic Test
1. CHECKING FOR LOSS OF PRIME DTC
With the scan tool, check for other Transmission DTCs.
Is the DTC P0944 present also?
Yes
- Diagnose and repair the DTC(s).
No
- Go to 2
2. CHECK FOR RELATED TRANSMISSION DTCS
With the scan tool, read Transmission DTCs.
Are any of the DTCs P0732, P0734 and/or P0846 present also?
Yes
- Replace the Transmission Solenoid/Pressure Switch Assembly.
- Perform 40/41TE VERIFICATION TEST 40/41TE Transmission Verification Test
No
- Go to 3
3. CHECK IF THE DTC P0845 IS CURRENT
With the scan tool, view 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 9
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 switch to 2/4.
With the scan tool, monitor the 2/4 Pressure Switch state while pressing the Pressure Switch Test button on the Transmission Simulator.
Wiggle the wires leading to the PCM while pressing and holding the Pressure Switch Test button.
Did the 2/4 Pressure Switch state change to closed and remain closed while wiggling the wires?
Yes
- Disassemble and inspect the Valve Body and repair or replace as necessary. If no problems are found in the Valve Body, replace the Transmission Solenoid/Pressure Switch Assembly.
- Perform 40/41TE VERIFICATION TEST 40/41TE Transmission Verification Test
No
- Go to 5
5. CHECK THE (T47) 2/4 PRESSURE SIGNAL CIRCUIT FOR AN OPEN
Turn the ignition off to the lock position.
Disconnect the Transmission Simulator, Miller tool #8333 and the Electronic Transmission Adapter kit.
Disconnect the PCM C2 harness connector.
Measure the resistance of the (T47) 2/4 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 (T47) 2/4 Pressure Signal circuit for an open.
- Perform 40/41TE VERIFICATION TEST 40/41TE Transmission Verification Test
No
- Go to 6
6. CHECK THE (T47) 2/4 PRESSURE SIGNAL CIRCUIT FOR A SHORT TO GROUND
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 40/41TE VERIFICATION TEST 40/41TE Transmission Verification Test
No
- Go to 7
7. CHECK THE (T47) 2/4 PRESSURE SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE
Ignition on, engine not running.
With the scan tool under TIPM, actuate the Transmission.
Measure the voltage of the (T47) 2/4 Pressure Signal circuit.
Is the voltage above 0.5 volts?
Yes
- Repair the (T47) 2/4 Pressure Signal circuit for a short to voltage.
- Perform 40/41TE VERIFICATION TEST 40/41TE Transmission Verification Test
No
- Go to 8
8. CHECK THE (T16) TRANSMISSION CONTROL OUTPUT CIRCUIT FOR AN OPEN
NOTE: Continue actuation of the Transmission under TIPM.
Using a 12-volt test light connected to ground, check (T16) Transmission Control Output circuit in the Transmission Solenoid/Pressure Switch Assembly harness connector.
NOTE: The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery.
Does the test light illuminate brightly?
Yes
- 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
No
- Repair the Transmission Control Output circuit for an open or high resistance. If the fuse is open make sure to check for a short to ground.
- Perform 40/41TE VERIFICATION TEST 40/41TE Transmission Verification Test
9. 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 40/41TE VERIFICATION TEST 40/41TE Transmission Verification Test
No
- Test Complete.