Can-Bus Terminal Resistance, Powertrain, Checking: Notes

General Description

The Engine Control Module -J623- communicates with all Data Bus capable control modules via a CAN Data Bus.

These Data Bus capable control modules are connected via two data bus wires which are twisted together (CAN_High and CAN_Low), and exchange information (messages). Missing information on the Data Bus is recognized as a malfunction and may be stored by the Engine Control Module -J623- and the other control modules connected to the CAN-Bus.

Trouble-Free Operation Of The CAN-Bus Requires That It Have A Terminal Resistance. This Central Terminal Resistor Is Located In The Engine Control Module -J623-.

Special Tools And Workshop Equipment Required

Multimeter.
Wiring Diagram.

Test Requirements

Fuses OK.
Battery voltage OK.
Switch OFF all electrical and electronic accessories.
Vehicles with automatic transmission, ensure the selector lever position is in "P".
Vehicles with manual transmission, ensure the shifter lever position is in "N" with the parking brake applied.
Observe all safety precautions: SAFETY PRECAUTIONS .
View clean working conditions: CLEAN WORKING CONDITIONS .

Test Procedure

Step	Procedure	Result / Action to Take
1	PERFORM: Preliminary Check to verify the customers complaint. Refer to PRELIMINARY CHECK . -- Was Complaint verified?	-- YES: GO TO: Step 2 CAN-BUS TERMINAL RESISTANCE, POWERTRAIN, CHECKING - 2 . -- NO: GATHER more information from customer about the complaint.
2	IGNITION: OFF. The Engine Control Module -J623- must remain connected for the following step. The central terminal resistor is located in the Engine Control Module -J623-. REMOVE: Transmission Control Module -J217-. Refer to appropriate service information. CHECK: Transmission Control Module -J217- harness connector terminals 6 to 5 for resistance. SPECIFIED VALUE: 60 - 72 Ω (@ approx. 20° C). -- Was Value obtained?	-- YES: CONDITION: May be intermittent. PERFORM: Visual Inspection of wiring and component. CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 4 CAN-BUS TERMINAL RESISTANCE, POWERTRAIN, CHECKING - 4 . -- NO: GO TO: Step 3 CAN-BUS TERMINAL RESISTANCE, POWERTRAIN, CHECKING - 3 .
3	REMOVE: Engine Control Module - J623-. Refer to appropriate service information. CHECK: CAN bus circuit between the Transmission Control Module -J217- harness connector terminal 6 and the Engine Control Module -J623- harness connector T94 / 67 for resistance. CHECK: CAN bus circuit between the Transmission Control Module -J217- harness connector terminal 5 and the Engine Control Module -J623- harness connector T94 / 68 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Were Values obtained?	-- YES: REPLACE: Engine Control Module -J623-. Refer to appropriate service information. GO TO: Step 4 CAN-BUS TERMINAL RESISTANCE, POWERTRAIN, CHECKING - 4 . -- NO: PERFORM: Visual Inspection of wiring and component. CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 4 CAN-BUS TERMINAL RESISTANCE, POWERTRAIN, CHECKING - 4 .
4	Refer To The Final Procedure Below;