Table 4-2. Unit Troubleshooting-continued -706880229

TM 5-4210-233-14&P-1

Table 4-2. Unit Troubleshooting - Continued

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

ELECTRICAL SYSTEM - EMERGENCY MASTER CIRCUITS - Continued

ROTATING BEACONS (CAB ROOF) WILL NOT ROTATE

(Refer to Electrical Wiring Diagrams, Appendix H, Sheet 1 of 16.)

Step 1. Check motor.

Replace motor (see para 4-85).

Step 2. Check wiring to motor for continuity.

Replace wire (see para 4-9.4).

ROTATING BEACONS DO NOT ILLUMINATE

(Refer to Electrical Wiring Diagrams, Appendix H, Sheet 1 of 16.)

Step 1. Check bulb.

Replace bulb (see para 4-85).

Step 2. Check brush and collector ring assembly for good electrical contact.

Replace brush/collector assembly (see para 4-85).

Step 3. Check wiring for continuity.

Replace wire (see para 4-9.4).

ROTATING BEACONS DO NOT OPERATE

(Refer to Electrical Wiring Diagrams, Appendix H, Sheet 1 of 16.)

Step 1. Check switch.

Replace switch (see para 4-94).

Step 2. Check "roof light" solenoid for proper operation.

Replace solenoid (see para 4-9.4).

Step 3. Check for +12V at emergency master buss.

Refer to "+12 volts not present at emergency master buss" troubleshooting procedure.

Step 4. Check for +1 2V at circuit breaker #1 on emergency master buss.

Replace breaker (see para 4-99).

4-100