DTC 4-4-3 Pump Motor/Relay Electrical Or Mechanical Fault

CONDITIONS FOR DTC
Once the car starts to move and reaches a speed of around 4 miles/h (6 km/h), the control module checks that there is no fault in the hydraulic modulator pump motor circuit in terms of poor connections, open-circuit or short-circuit. If a fault occurs in the pump motor or pump motor relay, the control module posts the DTC on the move.

SYMPTOMS
ABS warning light is on. ABS system out of action.

SOURCES OF FAULT
^ Faulty pump motor relay.
^ Faulty pump motor.
^ No control voltage to pin 12 on hydraulic modulator connector.
^ No monitoring signal to control module, i.e. open-circuit or short-circuit to 0 volts.

CHECKING VOLTAGE
1. Ignition off.
2. Connect a voltmeter between car ground (0 volts) and pin 8 on hydraulic modulator connector.
3. Ignition on.
4. Voltmeter should read battery voltage (approx. 12 volts).
5. If reading is correct Go below to Checking voltage to pump motor relay.

IF READING IS INCORRECT
1. Ignition off.

CARS WITH TRANSIENT SURGE PROTECTION RELAY
2. Connect an ohmmeter between transient surge protection relay pin 2 and hydraulic modulator connector pin 8.
3. If ohmmeter reading is approx. 0 ohms, lead is OK. Go below to Checking resistance in motor winding.
4. Ohmmeter reads infinite resistance: Open-circuit in lead. Repair open-circuit.

CARS WITHOUT TRANSIENT SURGE PROTECTION RELAY
2. Connect test box between control module and ABS connector.
3. Take ohmmeter readings between # 17 and hydraulic modulator connector pin 8.
4. If ohmmeter reading is 0 ohms, lead is OK. Go below to Checking resistance in motor winding.
5. Ohmmeter reads infinite resistance: Open-circuit in lead.
6. Repair open-circuit
7. Check DTC after repair.

CHECK VOLTAGE TO PUMP MOTOR RELAY
1. Ignition off.
2. Connect a voltmeter between ground (0 volts) and pin 9 on hydraulic modulator connector. Take a spare lead and connect one end to the ground point and the other to pin 12 on the hydraulic modulator connector.

NOTE: Do not leave connection in place for more than 2 seconds.

3. Voltmeter should read battery voltage (approx. 12 volts) each time pin 12 on the hydraulic modulator is at 0 volts.
4. Pump motor relay on hydraulic modulator should trip and the pump motor start.
5. If reading is correct: Go below to Checking lead resistance in control circuit(open-circuit).
6. If reading is incorrect: If voltmeter reading is 0 volts. Replace pump motor relay. If voltmeter reads battery voltage (approx. 12 volts) and engine will not start, go to Checking resistance in motor winding.

CHECKING RESISTANCE IN MOTOR WINDING
1. Ignition off.
2. Connect an ohmmeter between ground (0 volts) and pin 9 on hydraulic modulator connector. Ohmmeter reading should show low resistance, approx. 0.2 ohms.
3. If reading is incorrect: If ohmmeter reads infinite resistance, there is an open-circuit in the motor windings. Replace hydraulic modulator.

CHECKING LEAD RESISTANCE IN CONTROL CIRCUIT (OPEN-CIRCUIT)
1. Ignition off.
2. Disconnect control module from adapter.
3. Connect an ohmmeter between # 28 on the test box and pin 12 on the hydraulic modulator connector. Ohmmeter should read 0 ohms: if so, lead is OK. Go to Checking lead resistance in monitoring circuit (open-circuit).
4. If reading is incorrect: If ohmmeter reads infinite resistance, check lead for open-circuit Checking leads. Deal with open-circuit. Check DTC after repairs.

CHECKING LEAD RESISTANCE IN MONITORING CIRCUIT (OPEN-CIRCUIT)
1. Ignition off.
2. Connect an ohmmeter between # 14 on test box and pin 9 on hydraulic modulator connector. Ohmmeter should read 0 ohms. Lead is OK.
3. If reading is incorrect:
4. If ohmmeter reads infinite resistance, check lead for open-circuit. Repair open-circuit. Check DTC after repair.