TM-9-2320-285-24-1

TRUCK TRACTOR, YARD TYPE, 43,500 LB GVW, DED, 4X2, ARMY MODEL M878A1

TECHNICAL MANUAL; ORGANIZATIONAL, DIRECT SUPPORT AND GENERAL SUPPORT MAINTENANCE MANUAL

OCTOBER 1985

TM-9-2320-285-24-1 - Page 206 of 987

TM 9-2320-285-24-1

2-20.

LIGHT SYSTEMS TROUBLESHOOTING (CONT)

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

2.

TRAILER LIGHTS INOPERATIVE (24-VOLT TRAILER) (Cont)

Step 6.

Connect voltmeter leads to 24V inverter BAT.+ terminal and tractor ground.

a.

If voltmeter indicates zero volts, repair brown/orange electrical lead between 24V inverter terminal and

40A circuit breaker by splicing a new length of the same size (gage) wire.

b.

If voltmeter indicates 12-14 Vdc, go to step 7 below.

Step 7.

Connect voltmeter to IGN terminal of 24V inverter and to ground.

a.

If voltmeter indicates zero volts, repair black/yellow electrical lead between 24V inverter terminal and

24V INVERTER switch by splicing in a new length of the same size (gage) wire.

b.

If voltmeter indicates 12-14 Vdc, go to step 8 below.

Step 8.

Remove 20 ampere and 30 ampere fuses from 24V inverter (para 2-30).

Use an ohmmeter to check continuity of fuses.

a.

If continuity is not obtained, replace fuses (para 2-30).

b.

If continuity is obtained, go to step 9 below.

Step 9.

Turn key switch to on position.

Push up 24V INVERTER switch.

Pull out headlight switch fully.

Push in hazard warning switch.

Use voltmeter to check for 12 Vdc at terminals 4, 5, and 6 of 24V

inverter.

a.

If voltmeter indicates zero at terminal 4, go to Malfunction 5.

b.

If voltmeter indicates zero at terminal 5 or 6, go to Malfunction 3.

c.

If voltmeter indicates 12 Vdc at all three terminals, go to step 10 below.

2-183