Lin-Bus Circuit, Checking: Overview
Special tools and workshop equipment required
- Multimeter.
- Wiring diagram.
Test requirement
- A LIN Bus malfunction was recognized.
- The Motronic Engine Control Module (ECM) - J623- 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 (GND) connections between engine/transmission/chassis OK.
- Ignition switched off.
Function
The Engine Control Module (ECM) is connected to the Radiator Identification Sensor - G611- module via the LIN data Bus 3 wire connector. Radiator I.D. and a temperature signal are sent on the LIN bus to the ECM. If the information from the RIS module was not sent or cannot be read, the ECM will store a fault code.
Test procedure
-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK
Start diagnosis
-- Disconnect the Radiator Identification Sensor - G611- electrical harness connector.
-- Switch the ignition On.
-- Using a Multimeter, connect the red Multimeter lead to terminal 3 of the Radiator Identification Sensor - G611- module connector and the black lead to ground.
Specified value: Battery voltage.
-- Switch the ignition off.
If the specified value was Not obtained:
-- Check for an open or grounded circuit between terminal 3 and fuse SB15 in Fuse Panel B.
-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
-- Repair the circuit and replace any open fuses.
-- Go to Final procedures
If the specified value was obtained:
-- Connect the black Multimeter lead to terminal 1 of the Radiator Identification Sensor - G611- harness connector and the red lead to Battery voltage.
-- Switch the ignition On.
Specified value: Battery voltage.
-- Switch the ignition off.
If the specified value was Not obtained:
-- Check for an open circuit or high resistance between Radiator Identification Sensor - G611- terminal 1 and the Motronic Engine Control Module (ECM) - J623- connector terminal 52.
-- Check the wiring connection for damage, corrosion, loose or broken terminals.
-- If necessary, repair the faulty wiring connection, if no faults were found with the wiring or connections. Replace the Motronic Engine Control Module (ECM) - J623 -. Refer to appropriate service information.
-- Go to Final procedures
If the specified value was 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.
-- Disconnect the Motronic Engine Control Module (ECM) - J623- T94 electrical harness connector.
-- Disconnect the Radiator Identification Sensor - G611- module T3 electrical harness connector.
-- Using a Multimeter, check the Motronic Engine Control Module (ECM) - J623- T94 electrical harness connector terminal 64 to the Radiator Identification Sensor - G611- module T3 electrical harness connector terminal 2 for resistance.
| Radiator Identification Sensor - G611- electrical harness connector terminal | Motronic Engine Control Module (ECM) electrical harness connector T94 terminal or test box socket |
|---|---|
| 2 | 64 |
Specified value: 1.5 Ω max
If the specified value was not obtained:
-- Check the wiring connection for damage, corrosion, loose or broken terminals.
-- If necessary, repair the faulty wiring connection.
-- Go to Final procedures
If the specified value was obtained:
-- Replace the Radiator Identification Sensor - G611- (with radiator assembly).
Final procedures
-- Reinstall the engine cover with air filter, if necessary. Refer to the appropriate service information.
-- 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 .