Modulator & Solenoid Valves
- Measure resistance between terminals No. 1 and 3. Resistance should be 3.8-4.8 ohms. Check resistance between terminals No. 2 and 4. Resistance should be 4.5-5.5 ohms. If the specifications are not correct, replace the valves.NOTE: If circuit tester is unavailable, check the operating sound of the solenoid valves. If no operating sound, replace solenoid valves.CAUTION: Do not connect battery to solenoid valves for more than one minute.
- Inspect vacuum hoses for defects. Inspect the modulator check valves and brake power unit for clogging conditions.
- Using 2 pressure gauges with a range of 0-2500 psi (0-175.75 kg/cm2 ) , connect one gauge between modulator master cylinder port and master cylinder, and other to modulator rear brake port. Let engine run at idle.
- Depress brake pedal until 711 psi (50 kg/cm2 ) reads on rear brake gauge. Operate release solenoid valve. Pressure should drop to zero psi.
- With release solenoid still operated, operate the build-up solenoid. Stop operation of release solenoid. If pressure rises to 711 psi (50 kg/cm2 ) , the modulator is operating correctly.
- Repeat steps 4) and 5), but do not operate build-up solenoid. When release solenoid operation is cut-off, pressure should rise to 711 psi ( 50 kg/cm2 ) . If so, the operation is okay.
- Set both solenoid valves in a non-operating position. Increase pressure on master cylinder by operating brakes. Rear brake port gauge should show pressure of 1422 psi (100 kg/cm2 ) . Master cylinder gauge should show 1707 psi (120 kg/cm2 ) . If any test does not meet specifications, replace the modulator.