Table 4-2. Unit Troubleshooting-continued -706880271

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

4-2. Unit Troubleshooting-Continued

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

ELECTRICAL SYSTEM - APU AND 11O-VOLT CIRCUITS

1 AUXILIARY POWER UNIT (APU) DOES NOT START/RUN WITH CAB OR PUMP PANEL

CONTROLS (Refer to Electrical Wiring Diagrams, Appendix H, Sheet 15 of 16.)

Step 1. Check switch.

Replace switch (see para 4-22 or 4-94).

Step 2. Check common/start wires for continuity.

Replace wire (see para 4-9.4).

Step 3. Check electric fuel pump for proper operation.

Replace fuel pump (see para 4-216).

Step 4. Check APU start solenoid for proper operation.

Replace solenoid, Notify Direct Support.

Step 5. Check APU cranking motor.

Replace motor, Notify Direct Support.

2 AUXILIARY POWER UNIT (APU) RUNS, BUT NO POWER OUTPUT

(Refer to Electrical Wiring Diagrams, Appendix H, Sheet 15 of 16.)

Step 1. Check fuse on APU.

Replace fuse (see para 4-9.4).

Step 2. Check service panel circuit breakers are on.

Turn on service panel breaker.

Step 3. Check wiring for continuity.

Replace wire (see para 4-9.4).

Step 4. Check pump panel and cab panel volt and ammeters for output from APU.

Refer to APU troubleshooting procedures.

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