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P1740






P1740-TCC O/D SOL PERFORMANCE (DIESEL)

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


Theory of Operation


The Torque Converter Clutch (TCC) Solenoid is used to engage the TCC which improves fuel economy.


- When Monitored:

The Torque Convertor Clutch (TCC) and Overdrive Clutch (O/D) will be tested each time the ECM requests TCC engagement in 3rd gear and O/D.

- Set Condition:

The DTC will set if the expected rpm drop is not achieved while attempting to engage TCC or O/D. This indicates a malfunctioning torque convertor or overdrive clutch.







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



Diagnostic Test


1. ENGINE DTCS PRESENT

Ignition on, engine not running.

With the scan tool, read Engine DTCs.

Are there any Engine Temperature, Cam, Engine rpm, Misfire, P/N, or TPS DTC's present?

Yes

- Refer to the appropriate diagnostics.

No

- Go To 2



2. CHECK FOR OTHER TRANSMISSION DTCS PRESENT

Are any of the DTCs P0720, P0973, P0974, P2769, and/or P2770, also present?

Yes

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

No

- Go To 3



3. 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 4

No

- Go To 14



4. VERIFY THE TOW/ HAUL OVERDRIVE FEATURE


NOTE: The transmission fluid temperature must be above 0.0� C (32� F) before proceeding.

With the scan tool, build a custom display using: Engine rpm, Output Shaft Speed, TCC Solenoid, O/D Solenoid and TPS.


NOTE: This display will monitor the operation of the components.

Start the engine, turn off Overdrive or Tow Haul and test drive the vehicle.

Attain a steady speed of 88.5 Kmh or 55 mph with a minimum of 1.15 volts throttle opening for 20 seconds.


NOTE: Check the Shift pattern as the vehicle upshifts to speeds of 88.5 Kmh or 55 mph.

Is the Engine rpm within 60 rpm of the Output Shaft Speed rpm?

Yes

- Go To 10

No

- Go To 5



5. CHECK IF THE OUTPUT SPEED IS GREATER THAN ENGINE RPM

In the previous test, is the Output Shaft Speed greater than Engine rpm?

Yes

- Go To 6

No

- Go To 10



6. CALCULATE EXPECTED ENGINE RPM

With the scan tool, build a custom display using: Engine rpm, Output Shaft Speed, TCC Solenoid, O/D Solenoid and TPS.


NOTE: This display will monitor the operation of the components.

Start the engine, turn off Overdrive or Tow Haul and test drive the vehicle.

Attain a steady speed of 88.5 Kmh or 55 mph with a minimum of 1.15 volts throttle opening for 20 seconds.

With the scan tool, verify the 3-4 Solenoid (O/D) Solenoid is on and the TCC solenoid is locked


NOTE: Use this formula, Output Shaft Speed x 0.69 = expected Engine rpm.

Did the Engine rpm drop to 0.69 of the Output Shaft Speed rpm?

Yes

- Go To 10

No

- Go To 7



7. GOVERNOR PRESSURE SYSTEM TEST

Turn the ignition off to the lock position.

Connect a 0 to 2068 Kpa or 0 to 300 psi pressure gauge to the Overdrive Clutch Test Port.

Connect a 0 to 2068 Kpa or 0 to 300 psi pressure gauge to the Governor Test Port.

Start the engine.


NOTE: Allow the transmission temperature to rise to normal operating temperature.

While observing both pressure gauges, select 4th Gear from Gov and 3-4 System Test.


NOTE: The Governor pressure should rise to above 137.8 Kpa or 20 psi, shortly after the OD pressure should rise above 275.7 Kpa or 40 psi.

Did the pressures act as described?

Yes

- Go To 8

No

- Go To 9



8. CHECK IF THE OIL PAN CONTAINS EXCESSIVE DEBRIS

Remove the transmission oil pan.

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 10



9. CHECK THE 3-4 SHIFT SOLENOID

Turn the ignition off to the lock position.

Replace the 3-4 Solenoid.

Connect a 0 to 2068 Kpa or 0 to 300 psi pressure gauge to the Overdrive Clutch Test Port.

Connect a 0 to 2068 Kpa or 0 to 300 psi pressure gauge to the Governor Test Port.

Start the engine.


NOTE: Allow the transmission temperature to rise to normal operating temperature.

While observing both pressure gauges, select 4th gear from the Governor 3-4 shift valve system test.


NOTE: The Governor pressure should rise above 137.8 Kpa or 20 psi, shortly after the OD pressure should rise above 275.7 Kpa or 40 psi.

Did the pressures act as described?

Yes

- Test Complete.

No

- Overhaul the transmission. Carefully inspect the seals and clutches related to the OD Clutch.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test



10. TORQUE CONVERTER CLUTCH

Turn the ignition on.

With the scan tool, perform the Torque Converter Clutch test.

Did the engine stall?

Yes

- Go To 11

No

- Go To 13



11. GOVERNOR 3-4 SHIFT VALVE

Start the engine.

Perform the Governor and 3-4 Shift Valve System Test, select 4th gear.

Did the engine stall?

Yes

- Go To 12

No

- Go To 13



12. TCC SOLENOID

Replace the TCC Solenoid.

With the scan tool, perform the Governor and 3-4 Solenoid test, select 4th gear.

Did the engine stall?

Yes

- Repair internal transmission as necessary. Check for blocked passages.
- 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



13. SHAFT OR SEAL DAMAGE

Remove the Transmission Oil Pump.

Inspect the Reaction shaft, Input Shaft and Input seal.

Are any of the parts damaged or worn?

Yes

- Repair as necessary, also replace the Torque Converter.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test

No

- Replace the Torque Converter. NOTE: Inspect the Reaction Shaft, Input Shaft and Input Seal. Replace as necessary if any of the parts are damaged or worn.
- Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). Transmission Verification Test



14. INTERMITTENT WIRING & 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.