1. Check lamp operation.
A) disconnect the switch connector. Ground the connector terminal.
b) turn on the ignition: the indicator lamp should be on.
2. Checking the operation of the brake fluid level switch.
A) check the absence of conductivity between the sensor terminals with the float raised.
b) check for continuity between the sensor leads with the float lowered.
Replace sensor switch if necessary.
3. Checking the operation of the parking brake switch.
(YY, YH series)
A) check for continuity between the switch terminals with the parking brake lever raised.
b) check for continuity between the switch terminals with the parking brake lever down.
(series LY, LH)
Check the switch circuits according to the table.
If the continuity of the circuits is not as specified, replace the switch.
4. Checking the operation of the vacuum circuit breaker.
A) check the absence of conductivity between the terminals of the switch when the vacuum on the switch is 270-325 mm Hg.
b) check for continuity between the switch terminals in the absence of vacuum.