Anti-Lock Brake System: Testing: Modulator
- Connect 2 pressure gauges. See Fig 1
. One pressure gauge will connect between master cylinder and modulator, while other pressure gauge will connect to outlet point of modulator going to rear brakes. Pressure gauges must have a range of at least 0-2100 psi (0-148 kg/cm2
).
- Disconnect solenoid valve connector at modulator. Start engine. Depress brake pedal until pressure gauge connected to outlet point of modulator going to rear brakes reads 711 psi (50 kg/cm2
).
- While observing pressure gauge, connect battery voltage between terminals No. 1 and 3 of modulator. See Fig 1
. This will operate release solenoid valve. Pressure should suddenly drop to almost zero.
- Leave battery voltage connected between terminals No. 1 and 3. While observing pressure gauge connected to outlet point of modulator going to rear brakes, connect battery voltage between terminal No. 2 and 4 of modulator. See Fig 1
. This will operate build-up solenoid valve.
- Disconnect battery voltage between terminals No. 1 and 3. This disconnects battery voltage to release solenoid valve. Pressure should suddenly rise to 711 psi (50 kg/cm2
).
- Connect battery voltage between terminals No. 1 and 3. This operates release solenoid valve. With battery voltage disconnected from terminals No. 2 and 4 (build-up solenoid valve), disconnect battery voltage from terminals No. 2 and 4 (release solenoid valve). Observe pressure gauge connected to outlet point of modulator going to rear brakes. Gauge should read 710 psi (50 kg/cm2
).
- With battery voltage disconnected from both solenoid valves, increase fluid pressure of master cylinder. Observe both pressure gauges. Gauge connected to outlet point of modulator going to rear brakes should read 1422 psi (100 kg/cm2
) with brake pedal depressed.
- Gauge connected between master cylinder and modulator should read 1707 psi (120 kg/cm2
). If these pressure gauge readings are not to specification, replace modulator.
- Using a DVOM measure resistance between terminal No. 1 and 3 of modulator. This measures resistance of release solenoid valve. Resistance should be 3.8-4.8 ohms. See Fig 1
. Measure resistance between terminal No. 2 and 4. This measures resistance of build-up solenoid. Resistance should be 4.5-5.0 ohms. If resistance is not to specification, replace modulator.
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.