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.





For a complete Transmission Control Module Circuit Diagram, [1][2]Automatic Transmission/Transaxle.

For a complete CAN BUS Circuit Diagram, Communications.

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 scan tool, read Engine DTCs. Check and repair all engine DTCs prior to performing transmission symptom diagnostics.
With the scan tool, 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 scan tool, read Transmission DTCs.
Is DTC (P0720) CAN BUS CIRCUIT present?

Yes

- Diagnose and repair the DTC(s).

No

Go To 3

3. CHECK TO SEE IF ENGINE DTCS ARE PRESENT
With the ignition on.
With the scan tool, read Engine DTCs.
Are any performance or BUS related Engine DTCs present?

Yes

- Diagnose and repair the DTC(s).

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. Powertrain Control Module - Removal.
Turn the ignition on.
With the scan tool, erase Transmission DTCs.
Start the engine.
With the brakes firmly applied, shift the gear selector into drive.
With the scan tool, read Transmission DTCs.
Did DTC (P1793) ENGINE TORQUE REDUCTION set again?

Yes

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

No

- Test Complete.