Coolant Fan Control Module 2, Checking

Diagnostic Procedures

Coolant Fan Control Module 2, Checking

Special tools, testers and auxiliary items required

• Multimeter (VAG1526) or Multimeter (VAG1715)

• Connector test kit (VAG1594)

• Wiring diagram

Test requirements

• Fuses in E-box (plenum chamber, left) must be OK:





• Motronic Engine Control Module (ECM) Power Supply Relay (J271) must be OK, check:

• Battery voltage must be at least 11.5 volts.

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

• Parking brake must be engaged or else daylight driving lights will be switched on.

• For vehicles with automatic transmission, selector lever must be in P.

• If vehicle is equipped with an A/C system, it must be switched off.

• Ground (GND) connections between engine and chassis must be OK.

Test sequence

- Disconnect 4-pin connector from Coolant Fan Control (FC) Control Module 2 (J671) (- 2 -).





Checking voltage supply

- Connect multimeter to terminals 1+4 and 2+4 of connector for voltage measurement.





- Switch ignition on.

Specified value: at least 10.0 V

- Switch ignition off.

If there is no voltage:

- Check wires between 4-pin connector (terminals 1 and 2) and Motronic Engine Control Module (ECM) Power Supply Relay (J271) for open circuit according to wiring diagram.

Wire resistance: max. 1.5 ohms

- Check for open circuit in wire between 4-pin connector terminal 4 and Ground (GND) according to wiring diagram.

Wire resistance: max. 1.5 ohms

- Erase DTC memory of Engine Control Module (ECM) , Diagnostic mode 4: Reset/erase diagnostic data.

- Generate readiness code.

If there is no malfunction in voltage supply:

- Check wire to Engine Control Module (ECM) according to wiring diagram.

Checking wire to Engine Control Module (ECM)

- Connect test box to control module wiring harness , connect test box for wiring test.

- Check wire between test box and 4-pin connector for open circuit according to wiring diagram.





Terminal 3 + socket 104

Wire resistance: max. 1.5 ohms

- Check wire for short circuit to vehicle Ground (GND) and to B+.

Specified value: infinite ohms

- Erase DTC memory of Engine Control Module (ECM) , Diagnostic mode 4: Reset/erase diagnostic data.

- Generate readiness code.

If no malfunction is detected in wire and there was voltage present between terminals 1+4 and 2+4:

- Replace Coolant Fan Control (FC) Control Module 2 (J671) with Coolant Fan 2 (V177).

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 ] Monitors, Trips, Drive Cycles and Readiness Codes.