*NO RESPONSE FROM ECM (ENGINE CONTROL MODULE) - DIESEL

For a complete wiring diagram Refer to Section 8W.

Possible Causes

ENGINE CONTROL MODULE POWER AND GROUND

(D21) SCI TRANSMIT CIRCUIT SHORTED TO VOLTAGE

(D21) SCI TRANSMIT CIRCUIT SHORTED TO GROUND

(D21) SCI TRANSMIT CIRCUIT OPEN

TRANSMISSION CONTROL MODULE

ANTILOCK BRAKE MODULE

ENGINE CONTROL MODULE

Diagnostic Test

1. TEST FOR INTERMITTENT CONDITION

Turn the ignition on.

NOTE: Ensure the IOD fuse is installed and battery voltage is between 10.0 and 16.0 volts.

With the scan tool, select ECU view.

NOTE: A red X will be next to the module that is not communicating, indicating that the module is not active on the Bus network. A green check indicates that the module is active on the Bus network.

Does the scan tool display a red X next to the module?

Yes

Go To 2

The no response condition is not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring for chafed, pierced, pinched, and partially broken wires and the wiring harness connectors for broken, bent, pushed out, and corroded terminals.

2. CHECK ECM POWER AND GROUND

Check the ECM power and ground circuits. Refer to 9 - ENGINE ELECTRICAL DIAGNOSTICS - DIESEL for the diagnostic test procedure.

Were any problems found?

Yes

Repair as necessary.
Perform the ECM VERIFICATION TEST.

Go To 3

3. (D21) SCI CIRCUIT SHORTED TO GROUND AT ECM

Turn the ignition off.
Disconnect the scan tool from the DLC connector.
Disconnect the ECM C2 harness connector.
Measure the resistance between ground and the (D21) SCI Transmit circuit at the ECM harness connector.

Is resistance below 5.0 ohms?

Yes

Go To 4

Go To 6

4. (D21) SCI CIRCUIT SHORTED TO GROUND AT TCM

Disconnect the TCM harness connector.
Measure the resistance between ground and the (D21) SCI Transmit circuit at the TCM harness connector.

NOTE: If the vehicle is not equipped with a TCM, answer yes to the question.

Is resistance below 5.0 ohms?

Yes

Go To 5

Replace the Transmission Control Module in accordance with the service information.
Perform the BODY VERIFICATION TEST–VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE)

5. (D21) SCI CIRCUIT SHORTED TO GROUND AT ABS MODULE

Disconnect the ABS module harness connector.
Measure the resistance between ground and the (D21) SCI Transmit circuit at the ABS module harness connector.

Is resistance below 5.0 ohms?

Yes

Repair the (D21) SCI Transmit circuit for a short to ground.

Perform the BODY VERIFICATION TEST–VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE)

Replace the Antilock Brake System Module in accordance with the service information.
Perform the BODY VERIFICATION TEST–VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE)

6. (D21) SCI CIRCUIT SHORTED TO VOLTAGE AT THE DLC

Turn the ignition on.
Measure the voltage of the (D21) SCI Transmit circuit at the DLC connector.

Is the voltage above 10.0 volts?

Yes

Repair the (D21) SCI Transmit circuit for a short to voltage.

Perform the BODY VERIFICATION TEST–VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE)

Go To 7

7. (D21) SCI CIRCUIT OPEN AT THE DLC

Turn the ignition off.
Measure the resistance of the (D21) SCI Transmit circuit between the ECM connector and the DLC connector.

Is resistance below 5.0 ohms?

Yes

Replace the Engine Control Module in accordance with the service information.
Perform the ECM VERIFICATION TEST.

Repair the (D21) SCI Transmit circuit for an open.

Perform the BODY VERIFICATION TEST–VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE)