Can-Bus Terminal Resistance Instrument Cluster To Data Diagnostic Connector, Checking
The Engine Control Module -J623- communicates with all data-bus capable control modules via a CAN databus.
These databus 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 databus is recognized as a malfunction and stored.
Trouble-free operation of the CAN-bus requires that it have a terminal resistance. The central terminal resistor is located in the Engine Control Module -J623-.
Special tools and workshop equipment required
- Multimeter.
- Wiring diagram.
Test requirement
- A CAN-Bus malfunction was recognized.
- The Engine Control Module -J623- fuses OK.
- Battery voltage at least 12.5 V.
- Ignition switched OFF.
Test Procedure
-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK .
-- Disconnect the Instrument Cluster Control Module -J285- electrical harness connector T32 from the Instrument Cluster Control Module.
The Engine Control Module -J623- must remain connected for the following step.
-- Disconnect the Data Bus On Board Diagnostic Interface -J533- electrical harness connector T32b from the diagnostic interface.
-- Using a Multimeter, check continuity between J285 and J533.
Specified value: max. 1.5Ω (at Approx. 20° C).
| Instrument Cluster Control Module -J285- electrical harness connector terminals: | Data Bus On Board Diagnostic Interface -J533- electrical connector T32b terminals: |
|---|---|
| T32/4 (Can_Bus High) | T32b / 22 |
| T32/3 (Can_Bus Low) | T32b / 6 |
If the specified value was Not obtained:
-- Check the wiring connection for an open circuit, short circuit to Battery voltage or Ground (GND).
-- Check the wiring connection for damage, corrosion, lose or broken terminals.
-- If necessary, repair the faulty wiring connection.
If the specified value was obtained:
-- Replace the Engine Control Module -J623-. Refer to appropriate Service Information.
Final procedures
After the repair work, the following work steps must be performed in the following sequence:
- Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
- If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
- If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .