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48RE Automatic Transmission - Diesel






P0748-PRESSURE SOL CONTROL/TRANS RELAY CIRCUITS (DIESEL)





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


Theory of Operation


The Governor Pressure Solenoid is used to control governor pressure. Governor pressure is used to shift between first, second, and third gear.


- When Monitored:

Continuously with the ignition on.

- Set Condition:

This DTC will set if the ECM monitored voltage detected on the Governor Pressure Solenoid Control circuit is different than the expected voltage. Note: To clear this DTC, it is necessary to drive the vehicle at a sustained speed which would allow the TCC and/or Overdrive Clutch to operate.







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



Diagnostic Test


1. CHECK IF THE DTC P0882 IS PRESENT

Ignition on, engine not running.

With the scan tool, read Engine DTCs.

Is the DTC P0882 present also?

Yes

- Refer to the Transmission category and perform the appropriate symptom.

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 13



3. CHECK THE (T16) TRANSMISSION CONTROL RELAY OUTPUT CIRCUIT





Ignition on, engine not running.

With the scan tool, actuate the Transmission Control Output in the ECM.

Using a 12-volt test light connected to ground, back probe the (T16) Transmission Control Output circuit at the TIPM C10 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 cycle on and off and illuminate brightly?

Yes

- Go To 4

No

- Go To 10



4. CHECK THE (T16) TRANSMISSION CONTROL RELAY OUTPUT CIRCUIT





Ignition on, engine not running.

With the scan tool, actuate the Transmission Control Output in the ECM.

Using a 12-volt test light connected to ground, back probe the (T16) Transmission Control Output circuit at the Transmission Solenoid 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 cycle on and off and illuminate brightly?

Yes

- Go To 5

No

- Repair the (T16) Transmission Control Output Circuit for an open.



5. CHECK THE (T118) GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT FOR AN OPEN





Turn the ignition off to the lock position.

Disconnect the Transmission Solenoid Assembly harness connectors.

Disconnect the ECM C2 harness connector.

Measure the resistance of the (T118) Governor Pressure Solenoid Control circuit between the Transmission Solenoid Assembly harness connector and the ECM C2 harness connector.

Is the resistance below 5.0 ohms?

Yes

- Go To 6

No

- Repair the (T118) Governor Pressure Solenoid Control circuit for an open.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test



6. CHECK THE (T118) GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT FOR A SHORT TO GROUND





Measure the resistance between ground and the (T118) Governor Pressure Solenoid Control circuit.

Is the resistance below 5.0 ohms?

Yes

- Repair the (T118) Governor Pressure Solenoid Control circuit for a short to ground.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test

No

- Go To 7



7. CHECK THE (T118) GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT SHORT TO VOLTAGE





Ignition on, engine not running.

Measure the voltage of the (T118) Governor Pressure Solenoid Control circuit.

Is the voltage above 0.5 volt?

Yes

- Repair the (T118) Governor Pressure Solenoid Control circuit for a short to voltage.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test

No

- Go To 8



8. CHECK THE (T118) GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT





Turn the ignition off to the lock position.

Disconnect the TIPM C10 connector.

Measure the resistance between the (T118) Governor Pressure Solenoid Control circuit and all other circuits in the Transmission Solenoid Assembly harness connector.

Is the resistance below 5.0 ohms between the (T118) Governor Pressure Solenoid Control circuit and any other circuit in the Transmission Solenoid Assembly harness connector?

Yes

- Repair the (T118) Governor Pressure Solenoid Control circuit for a short to another circuit(s).
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test

No

- Go To 9



9. CHECK THE GOVERNOR PRESSURE SOLENOID

Remove the Transmission Oil Pan.

Check all internal wiring pertaining to the Governor Pressure Solenoid for an open, short, and bent or broken terminals.

If no internal wiring problems are found, replace the Governor Pressure Solenoid.

Drive the vehicle performing multiple upshifts and downshifts.

With the scan tool, read Transmission DTCs.

Does the 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

- Test Complete.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test



10. CHECK THE (T16) TRANSMISSION CONTROL OUTPUT CIRCUIT FOR OPEN.





Ignition on, engine not running.

Using the scan tool in the TIPM, actuate the Transmission.

Using a 12-volt test light connected to ground, back probe the (T16) Transmission Control Output circuit at the TIPM C10 harness connector.

Does the test light cycle on and off and illuminate brightly?

Yes

- Go To 11

No

- Using the schematics as a guide, check the Totally Integrated Power Module (TIPM) 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 TIPM.



11. CHECK THE (T515) TRANSMISSION CONTROL CIRCUIT





Turn the ignition off to the lock position.

Disconnect the TIPM C1 harness connector.

Ignition on, engine not running.

Using the scan tool in the ECM, actuate the Transmission.

Using a 12-volt test light connected to ground, check the (T515) Transmission Control circuit at the TIPM C1 harness connector.

Does the test light cycle on and off and illuminate brightly?

Yes

- Using the schematics as a guide, check the Totally Integrated Power Module (TIPM) 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 TIPM.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test

No

- Go To 12



12. CHECK THE (T515) TRANSMISSION CONTROL CIRCUIT FOR AN OPEN





Turn the ignition off to the lock position.

Disconnect the ECM C2 harness connector.

Connect a jumper wire between cavity 5 in the ECM C2 harness connector and ground.

Using a 12-volt test light connected to 12 volts, check the (T515) Transmission Control circuit at the TIPM C1 harness connector.

Does the test light illuminate brightly?

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

- Repair the (T515) Transmission Control circuit for an open.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test



13. 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.
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