CAN Bus Terminal Resistance, Checking

Diagnostic Procedures

CAN Bus Terminal Resistance, Checking

Special tools, testers and auxiliary items required

• Multimeter.

• Wiring diagram.

Test requirement

• A CAN-Bus malfunction was recognized.

• The Engine Control Module (ECM) ( J220) fuses OK.

• Battery voltage at least 12.5 volts.

• All electrical consumers such as, lights and rear window defroster, switched off.

• Vehicles with automatic transmission, shift selector lever into position " P" or "N".

• A/C switched off.

• Ground connections between engine/transmission/chassis OK.

• Ignition switched OFF.

Function

The Engine Control Module (ECM) (J220) communicates with other CAN-Bus capable control modules.

The control modules are connected by two data bus wires which are twisted together (CAN High and CAN Low), and exchange information (messages). Missing information on the CAN bus is recognized as a malfunction by the Engine Control Module (ECM) (J220) 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 Resistance is located in the Engine Control Module (ECM) (J220).

Test Procedure

- Perform a preliminary check to verify the customers complaint. Refer to => [ Preliminary Check ] Preliminary Check.

• The Engine Control Module (ECM) (J220) must remain connected for the following test.

- Remove the air cleaner assembly.

- Disconnect the ABS Control Module (J104) electrical harness connector.

- Using a multimeter, check the ABS Control Module (J104) electrical harness connector terminals 11 to 15 for the correct Terminal Resistance.

Specified value: 57 to 62 ohms (at approx. 20° C)

If the specified value was Not obtained:

Checking wiring

If the manufacturers test box is being used, perform the following step.

- Install the test box.

If the manufacturers test box is not being used, perform the following step.

- Remove the Engine Control Module (ECM) (J220). Refer to the Repair Information.

- Using a multimeter, check the ABS Control Module (J104) electrical harness connector through the Data Bus Diagnostic On Board Interface (J533) in the instrument cluster wiring harness to the Engine Control Module (ECM) ( J220) electrical harness connector for short to ground, high resistance or an open circuit. Refer to the Wiring Diagrams for harness details.





Specified value: 1.5 ohms Max.

If the specified value was Not obtained:

- Check the wiring connection for short to ground, high resistance or an open circuit.

- Check the wiring connection for damage, corrosion, loose or broken terminals.

- If necessary, repair the faulty wiring connection.

If no malfunction is found in the wiring and the Terminal Resistance was Not OK:

- Replace the Engine Control Module (ECM) (J220 ). Refer to the Repair Information.

If no malfunction is found in the wiring and the Terminal Resistance was OK:

- Replace the Data Bus On Board Diagnostic Interface (J533) (a component of the instrument cluster).

Final procedures

After the repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Modes 01 - 09.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Readiness Code.