Test Procedure

NOTE:

The Engine Control Module must remain connected for the following step:

-- Disconnect the Module that was no response, or the CAN Bus wires can be accessed at the Data Bus On Board Diagnostic Interface -J533-

-- Using a multimeter, measure the resistance between the CAN bus low and CAN bus high in the disconnected Module electrical connector. Refer to Wiring Diagrams for location.

Specified value: 58 to 72 Ω (at approx. 20° C)

If the specified value was obtained:

-- Check for power and ground present to the module that does not communicate. If the power and grounds are present to the Module, but the Module does not communicate, replace the Module that did not communicate on the Bus. Refer to the Repair Information for removal and installation procedures.

If the specified value was not obtained:

Checking wiring

-- Remove the Engine Control Module -J623- and disconnect the connectors. Refer to the service information for removal and installation procedures.

-- Using a multimeter, measure the resistance of the CAN Bus High circuit between the disconnected Module on the Bus and ECM. Repeat the procedure for the CAN Bus Low. Refer to Wiring Diagrams for pin locations.

Specified value: 1.5 Ω Max.

If the specification was Not obtained:

-- Check the wires for a short circuit, high resistance, or an open.

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

-- Repair as necessary.

If no malfunction is found in the wiring and the Bus resistance was Not obtained:

-- Replace the Engine Control Module -J623-. Refer to the Repair Information.