P1793

P1793 - ENGINE TORQUE REDUCTION





When Monitored and Set Condition

- When Monitored: Engine intervention active for at least 20 ms, no engine torque errors, engine torque demand is greater than 0.
- Set Condition: Torque Reduction acknowledge bit - not set, no shift aborts, the error flag Torque Reduction Acknowledge is not set, Powertrain controller not supporting torque requests.






Diagnostic Test


1. PRE-DIAGNOSTIC CHECK OUT





NOTE: Low fluid level can be the cause of many transmission problems. If the fluid level is low, locate and repair the leak then check and adjust the fluid level.

NOTE: Always perform diagnostics with a fully charged battery to avoid false symptoms.

With the DRB III(R), read Engine DTCs. Check and repair all engine DTCs prior to performing transmission symptom diagnostics.

With the DRB III(R), read and record all Transmission DTCs.


NOTE: Check connectors - Clean/repair as necessary. Poor pin to terminal connections can set DTCs.

Using the wiring diagram/schematic as a guide, inspect the wiring and connectors. Repair as necessary.

Most DTCs set on start up but some must be set by driving the vehicle such that all diagnostic monitors have run.


NOTE: Check for any Technical Service Bulletins that may apply.

Perform this procedure prior to Symptom diagnosis.

Continue

Go To 2



2. (P0720) CAN BUS CIRCUIT DTC PRESENT





Turn the ignition on.

With the DRB III(R), read Transmission DTCs.

Is DTC (P0720) CAN BUS CIRCUIT present?

Yes

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

No

Go To 3



3. CHECK TO SEE IF ENGINE DTCS ARE PRESENT





With the ignition on.

With the DRB III(R), read Engine DTCs.

Are any performance or BUS related Engine DTCs present?

Yes

- Refer to the appropriate symptom.

No

Go To 4



4. CAN C BUS (+) / (-) CIRCUIT OPEN





Turn the ignition off.

Disconnect the PCM C4 harness connector.

Disconnect the TCM C3 harness connector.


NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance of the CAN C BUS (+) circuit from the PCM C4 harness connector to the TCM C3 harness connector.

Measure the resistance of the CAN C BUS (-) circuit from the PCM C4 harness connector to the TCM C3 harness connector.

Is the resistance of both CAN C BUS circuits below 5.0 ohms?

Yes

Go To 5

No

- Repair the faulty CAN C BUS circuit(s) for an open.
- Perform NAG1 TRANSMISSION VERIFICATION TEST. Transmission Verification Test



5. PCM - ENGINE TORQUE REDUCTION





With the ignition off.

Replace and program the Powertrain Control Module.

Turn the ignition on.

With the DRB III(R), erase Transmission DTCs.

Start the engine.

With the brakes firmly applied, shift the gear selector into drive.

With the DRB III(R), read Transmission DTCs.

Did DTC (P1793) ENGINE TORQUE REDUCTION set again?

Yes

- Replace the Transmission Control Module.
- Perform NAG1 TRANSMISSION VERIFICATION TEST. Transmission Verification Test

No

- Test Complete.