Cooling Fan Control Circuit, Checking
Special tools and workshop equipment required
- Multimeter.
- Test lamp
- Wiring diagram.
Test requirements
- The Cooling Fan Module fuse S5 is OK.
- Battery voltage at least 12.5 V.
- All electrical consumers switched off.
- A/C switched off.
- The ignition switched OFF.
Test procedure
-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK .
Start diagnosis
-- Disconnect the Cooling Fan Control Module -- electrical harness connector.
Checking voltage supply
Switch the ignition ON.
-- Using a multimeter, check the Cooling Fan Control Module -- harness connector terminal 1 to ground for voltage.
-- Using a multimeter, check the Cooling Fan Control Module -- harness connector terminal 2 to ground for voltage.
Specified value for both terminals: Battery voltage.
Switch the ignition OFF.
If the specified value was Not obtained:
-- Check the wiring from the Cooling Fan Control Module -- harness connector terminal 1 to fuse S-163 or terminal 2 to fuse S-5 for high resistance, a short circuit to Ground, or an open circuit. Refer to the Wiring Diagram.
-- Check the harness connector for damage, corrosion, loose or broken terminals.
-- If necessary, repair the wiring connection and replace any blown fuse.
If the specified value was obtained:
-- Connect a test lamp to Battery positive. Connect the other end to terminal 4 of the Cooling Fan Control Module -- harness connector.
Specified value: Test lamp is ON.
If the specified value was Not obtained:
-- Check the wiring for an open or high resistance.
-- Check the harness connector for damage, corrosion, loose or broken terminals.
-- If necessary, repair the faulty wiring connection.
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.
-- Remove the Motronic Engine Control Module (ECM) -J220-. Refer to the Repair information.
-- Using a multimeter, check the Cooling Fan Control Module --N112-- harness connector terminal 3 to the Motronic Engine Control Module (ECM) -J220- electrical harness connector T121 for high resistance or an open circuit.
| Cooling Fan Control Module -- electrical harness connector terminal | Motronic Engine Control Module (ECM) -J220- electrical connector T121 terminal or test box socket |
|---|---|
| 3 | 66 |
Specified value: 1.5 Ω Max.
If the specified value was Not obtained:
-- Check the wiring for an open, high resistance or short to ground.
-- Check the harness connector for damage, corrosion, loose or broken terminals.
-- If necessary, repair the faulty wiring connection.
If no malfunction is detected in the wiring:
-- Replace the Motronic Engine Control Module (ECM) -J220-. Refer to the Repair 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 .