Coolant Pump, Checking

Diagnostic Procedures

Coolant Pump, 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 2 (J670) must be OK, check:

• Auxiliary Engine Coolant (EC) Pump Relay (J496), -position A° must be OK, checking:

• Battery voltage must be at least 11.5 volts.

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

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

• Ignition switched off.

Test sequence

- Disconnect 2-pin connector - 1 - from Coolant Pump (V36) (- 2 -).





- Connect coolant pump to the B+ and Ground (GND) terminals of the battery using the respective adapter cables.

Pump must run.

If pump does not run:

- Disconnect connection between pump and battery.

- Replace Coolant Pump (V36).

CAUTION!
• The cooling system is under pressure.

• Danger of scalding when opening!

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

- Generate readiness code.

If pump runs:

- Disconnect connection between pump and battery.

- Remove Auxiliary Engine Coolant (EC) Pump Relay (J496) from relay carrier, position A5.





• Do not use metallic tools to pry off relays from relay carrier. The terminals could conduct electricity.

- Check wire between terminal 2 of relay carrier and terminal 1 of 2-pin connector of Coolant Pump (V36) for open circuit according to wiring diagram.





Wire resistance: max. 1.5 ohms

- Also check the wire for short circuit to B+ and Ground (GND).

Specified value: infinite ohms

- Check wire between 2-pin connector terminal 2 and Ground (GND) for open circuit according to wiring diagram.





Wire resistance: max. 1.5 ohms

If no malfunctions are found in wires:

- Now check voltage supply of Auxiliary Engine Coolant (EC) Pump Relay (J496).

- Connect multimeter to terminal 1 of relay carrier and Ground (GND) for voltage measurement.





- Switch ignition on.

Specified value: at least 10.0 V

- Switch ignition off.

If specified value is not obtained:

- Locate and repair open circuit using wiring diagram:

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

- Generate readiness code.

If specified value is obtained:

- 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 relay carrier for open circuit according to wiring diagram.





Terminal 5 + socket 48

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 the wire:

- Replace Motronic Engine Control Module (ECM) (J220).

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.