Steering Control Module: Testing and Inspection

COMPONENTS

INSPECTION

NOTICE: When replacing PPS ECU, be careful not to also replace tilt and telescopic ECU.

1. INSPECT ECU-IG FUSE (Instrument panel J/B)
2. INSPECT PPS ECU CIRCUIT
a. Disconnect the PPS ECU connector.








b. Inspect the connector on wire harness side, as shown in the illustration.
If the circuit is not as specified, check and replace the wire harness.
If the circuit is not as specified, inspect the speed sensor.





3. INSPECT PPS SOLENOID VALVE
a. Disconnect the PPS solenoid connector.
b. Measure the resistance between the terminals of the solenoid 1 and 2.

Resistance: 6 - 11 Ohms

If it is not as specified, replace the pressure control valve with the solenoid valve.





c. Check the PPS solenoid operation.
1. Connect the battery positive terminal to the solenoid terminal 1.
2. Connect the battery negative terminal to the solenoid terminal 2.
3. Check that the solenoid makes a "clicks" sound. If it is faulty, replace the pressure control valve with the solenoid valve.

NOTICE:
^ Do not apply voltage for more than 30 seconds to avoid burning out the solenoid.
^ If repeating this step, wait until the solenoid cools down enough that it can be touched by hand.

d. Connect the PPS solenoid connector.
e. Inspect the PPS solenoid valve circuit.
1. Disconnect the PPS ECU connector.








2. Check continuity between the terminals of the connector on wire harness side, as shown in the illustration.
3. Connect the PPS ECU connector.
4. INSPECT PPS ECU
a. Jack up the vehicle and support it on stands.
b. Start the engine.
c. Measure the voltage of ECU.





1. Using a voltmeter, measure the voltage between ECU terminals 2 and 6 while the engine is idling.

Standard voltage: 0.33 - 0.43 V





2. Place the transmission in gear and while running at about 37 mph (60 km/h), measure the voltage between ECU terminals 2 and 6.

Standard voltage: 0.09 - 0.21 V

If no voltage, try another ECU for LEXUS SC400/300.
d. Lower the vehicle.