Coolant Fan Control Modules, Checking

Diagnostic Procedures

Coolant Fan Control Modules, Checking

Special tools, testers and auxiliary items required

• Hand multimeter (V.A.G 1526) or Multimeter (V.A.G 1715)

• Test adapter kit (V.A.G 1594)

• Wiring diagram

Test conditions

• Battery voltage (both batteries) must be at least 11.5 Volts.

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

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

• Parking brake must be engaged.

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

• Ignition switched off.

• Motronic Engine Control Module (ECM) Power Supply Relay 2 (J670) must be OK, checking:

• Fuses in right instrument panel fuse holder must be OK:

Right instrument panel fuse holder





Test Sequence

- Disconnect corresponding 4-pin harness connector from Coolant Fan Control (FC) Control Module (J293):

• 4-pin connector - arrow - from Coolant Fan Control (FC) Control Module (J293)





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





Checking voltage supply

- Connect multimeter to terminals 1 + 4 and 2 + 4 of connector to Engine Control Module (ECM) for voltage measurement.





- Switch ignition on. Specification: at least 10.0 V

- Switch ignition off.

If no voltage is present:

- Check wiring between 4-pin connector (terminals 1 and 2) and corresponding fuses in right instrument panel fuse holder for short circuit according to wiring diagram. Wiring resistance: max. 1.5 ohms





Right instrument panel fuse holder





- Check for open circuit in wire between 4-pin connector terminal 4 and Ground (GND) according to wiring diagram. Wiring resistance: max. 1.5 ohms

- Erase DTC memory of Engine Control Module => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09, Diagnostic mode 4: Reset/erase diagnostic data.

- Generate readiness code => [ Readiness Code, Generating ] Monitors, Trips, Drive Cycles and Readiness Codes.

If there is no malfunction in the voltage supply:

- Check wire to Engine Control Module according to wiring diagram.

Checking wire to Engine Control Module (ECM)

- Connect test box to Engine Control Module (ECM) (J623) wiring harness on connecting test box for wiring test, refer to Repair Information.

- Check wire between test box and 4-pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram. Wiring resistance: max. 1.5 ohms









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

- Erase DTC memory of Engine Control Module => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09, Diagnostic mode 4: Reset/erase diagnostic data.

- Generate readiness code => [ Readiness Code, Generating ] Monitors, Trips, Drive Cycles and Readiness Codes.

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

- Replace corresponding Coolant Fan Control Module:





• Coolant Fan Control (FC) Control Module 2 (J293) - 5 - with Coolant Fan (V7) - 4 -

• Coolant Fan Control (FC) Control Module 2 (J671) - 1 - with Coolant Fan 2 (V177) - 2 -

- Erase DTC memory of Engine Control Module => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09, Diagnostic mode 4: Reset/erase diagnostic data.

- Generate readiness code => [ Readiness Code, Generating ] Monitors, Trips, Drive Cycles and Readiness Codes.