P1757

P1757-GOV PRESS ABOVE 3 PSI IN GEAR WITH 0 MPH (DIESEL)





For a complete wiring diagram refer to Diagrams/Electrical. Electrical Diagrams


Theory of Operation


The Governor Pressure Control System is used to regulate the governor pressure which controls the shifts for first, second, and third gear. The Governor Pressure Control System test verifies that the requested pressure and the actual pressure are within a predetermined tolerance.


- When Monitored:

While the engine is running and the gear selector is in the Drive position.

- Set Condition:

This DTC will set if the monitored Governor Pressure is greater than 41.4 kPa (6 psi) for 5 seconds while the gear selector is in the Drive position with the road speed equal to zero - six times during a drive cycle. The transmission oil temperature must be between 23 - 88� C (73 - 190� F).







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Checkout (Diesel)



Diagnostic Test


1. OTHER TRANSMISSION DTC'S PRESENT

Ignition on, engine not running.

With the scan tool, read Engine DTCs.

Are there any other Transmission DTCs present?

Yes

- Refer to the Transmission category and perform the appropriate symptom(s).

No

- Go To 2



2. CHECK IF THE DTC IS CURRENT

With the scan tool, read Engine DTCs.

Record the Freeze Frame data for the reported DTC.

With the scan tool, erase DTCs.

Turn the ignition off to the lock position.

Using the Freeze Frame data recorded earlier, try to duplicate the conditions in which the DTC originally set.


NOTE: It may be necessary to road test the vehicle to duplicate the original set conditions.

With the scan tool, read Engine DTCs.

Did the DTC reset?

Yes

- Go To 3

No

- Go To 11



3. CHECKING FOR GOVERNOR PRESSURE ABOVE 6 PSI

Start the engine.


CAUTION: Apply the parking brake.

Warm the transmission to a normal operating temperature above 43� C (110� F).


CAUTION: Firmly apply the brakes.

With the engine RPM at idle, place the gear selector in Drive.

With the scan tool, read the governor pressure.

Is the governor pressure above 41.4 kPa (6 psi)?

Yes

- Go To 4

No

- Go To 11



4. GOVERNOR PRESSURE MATCH GAUGE PRESSURE

Turn the ignition off to the lock position.

Install a 700 kPa (100 psi) pressure gauge to the Governor Pressure Test Port.

Start the engine.

Warm the transmission to a normal operating temperature above 43� C (110� F).


CAUTION: Firmly apply the brakes.

With the engine RPM at idle, place the gear selector in Drive.

With the scan tool, read the governor pressure and compare the scan tool reading to the pressure gauge reading.

Does the scan tool Governor Pressure reading match the pressure gauge reading within 6.9 kPa (1 psi)?

Yes

- Go To 5

No

- Go To 8



5. CHECK FOR BURNT TRANSMISSION FLUID AND/OR EXCESSIVE DEBRIS IN THE TRANSMISSION OIL PAN

Turn the ignition off to the lock position.

Remove the transmission oil pan and inspect for burnt transmission fluid and excessive debris.

Is the transmission fluid burnt or does the transmission oil pan contain excessive debris?

Yes

- Repair internal transmission as necessary.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test

No

- Go To 6



6. REPLACE THE GOVERNOR PRESSURE SOLENOID AND CHECK THE VALVE BODY

Replace the Governor Pressure Solenoid.

Start the engine.

Warm the transmission to a normal operating temperature above 43� C (110� F).


CAUTION: Firmly apply the brakes.

With the engine RPM at idle, place the gear selector in Drive.

Read the governor pressure on the pressure gauge.

Is the governor pressure on the pressure gauge above 41.4 kPa (6 psi) with the engine RPM at idle and the gear selector in Drive?

Yes

- Replace the Valve Body.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test

No

- Go To 7



7. ENGINE CONTROL MODULE

Turn the ignition off to the lock position.

Remove pressure gauge from transmission.

Install the Transmission Oil Pan and refill the transmission fluid.

With the scan tool, erase Engine DTCs.

Test drive the vehicle.

Be sure to stop the vehicle, with the vehicle in drive on six separate occurrences for at least 6 seconds each stop.

With the scan tool, read Engine DTCs.

Did the P1757 DTC reset?

Yes

- Using the schematics as a guide, check the Engine Control Module (ECM) pins, terminals, and connectors 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 ECM.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test

No

- Go To 11



8. CHECK THE 5 VOLT SUPPLY CIRCUIT FOR AN OPEN





Turn the ignition off to the lock position.

Disconnect the ECM harness connectors.

Disconnect the Transmission Solenoid Assembly harness connector.

Measure the resistance of the 5-volt Supply circuit between the Transmission Solenoid Assembly harness connector and the ECM harness connector.

Is the resistance below 5.0 ohms?

Yes

- Go To 9

No

- Repair the 5-volt Supply circuit for an open.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test



9. CHECK THE 5 VOLT SUPPLY CIRCUIT FOR AN OPEN INSIDE THE TRANSMISSION





Reconnect the Transmission Solenoid Assembly harness connector.

Remove the transmission oil pan.

Disconnect the Governor Pressure Sensor connector internal to the transmission.

Measure the resistance of the 5-volt Supply circuit between the ECM C2 harness connector and the Transmission Solenoid Assembly connector internal to the transmission.

Is the resistance below 5.0 ohms?

Yes

- Go To 10

No

- Repair or replace the 5-volt Supply circuit for an open internal to the transmission.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test



10. CHECK THE ENGINE CONTROL MODULE - 5 VOLT SUPPLY





Reconnect the ECM harness connectors.

Ignition on, engine not running.

Measure the voltage of the 5-volt Supply circuit in the Governor Pressure Sensor connector internal to the transmission.

Is the voltage between 4.5 and 5.5 volts?

Yes

- Replace the Governor Pressure Sensor.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test

No

- Using the schematics as a guide, check the Engine Control Module (ECM) pins, terminals, and connectors 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 ECM.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test



11. INTERMITTENT WIRING AND CONNECTORS

The conditions necessary to set this DTC are not present at this time.

Use the Freeze Frame Data to help duplicate the conditions in which the DTC originally set. Pay particular attention to the DTC set conditions, such as, VSS, MAP, ECT, and Load

Using the schematics as a guide, visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or partially broken wires.

Visually inspect the related wiring harness connectors. Look for broken, bent, pushed out, or corroded terminals.

Wiggle the wiring and connectors while checking for any possible open or shorted circuits.

Check for any Service Information Tune-ups or Technical Service Bulletins that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test

No

- Test Complete.