Electric Coolant Pump Checking

Special tools and workshop equipment required 

• Multimeter.
• Wiring diagram.

Test requirements 

• The Auxiliary Engine Coolant Pump Relay -J496- OK.
• The Coolant Pump -V50- fuse 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 connections between engine/transmission/chassis OK.
• Ignition switched off.
• Engine cold.

Test procedure 

-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK .

Start diagnosis 

-- Disconnect the Coolant Pump -V50- electrical harness connector.

Checking voltage 

Switch the ignition On.

-- Using a multimeter, check the Coolant Pump -V50- electrical harness connector terminal 1 to Ground for voltage.

Specified value: Battery voltage.

Switch the ignition Off.

If the specified value was Not obtained:

-- Check the wiring from the Coolant Pump -V50- electrical connector terminal 1 to the Auxiliary Engine Coolant Pump Relay -J496- socket 2/87 for a short circuit to Ground, high resistance, or an open circuit.

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

-- If necessary, repair the wiring connection.

If the specified value was obtained:

Checking Ground 

-- Using a multimeter, check the Coolant Pump -V50- electrical connector terminal 2 to Ground for resistance.

Specified value: 1.5 Ω Max.

If the specification was Not obtained:

-- Check the wiring from the Coolant Pump -V50- electrical connector terminal 1 to Ground connection on electronic fan control for or an open circuit, high resistance, a short circuit to Battery (+) or Ground.

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

-- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring and the voltage supply was Not OK:

-- Replace the Auxiliary Engine Coolant Pump Relay -J496-.

-- Erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .

-- Perform a road test to verify repair.

If the DTC does not return:

Generate readiness code. Refer to READINESS CODE .

If the DTC returns, no malfunction is detected in the wiring and voltage supply was OK:

-- Replace the Coolant Pump -V50-.

Final procedures 

After 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 .
2. If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
3. If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .