LIGHT SYSTEMS TROUBLESHOOTING

TM 10-3930-638-24&P

2-24. LIGHT SYSTEMS TROUBLESHOOTING

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

1. FRONT FLOOD LIGHTS INOPERATIVE

NOTE

If one or more front flood light operates normally, replace bulb in affected

flood light (para 2-30a). If flood light is still inoperative, check for open

circuit in wire between inoperative flood light and FRONT FLOOD switch.

Step 1.

Turn IGNITION switch to OFF and remove key.

Disconnect 10 ampere circuit breaker wire from terminal on FRONT FLOOD switch.

Connect ohmmeter leads to leads of 10 ampere circuit breaker.

a. If ohmmeter indicates less than 0.1 ohm, proceed to step 2.

b. If ohmmeter indicates more than 0.1 ohm, connect ohmmeter leads to vehicle ground and 4-wire

terminal of FRONT FLOOD switch. If ohmmeter indicates less than 2 ohms, check for short

in wiring between FRONT FLOOD switch and front flood lights. Replace 10 ampere circuit

breaker after short is removed (para 2-28a).

Step 2. Connect ohmmeter leads to terminals of FRONT FLOOD switch and set FRONT FLOOD switch at

ON position.

a. If ohmmeter indicates less than 0.1 ohm, reconnect lead of 10 ampere circuit breaker to

terminal of FRONT FLOOD switch and proceed to step 3.

b. If ohmmeter indicates more than 0.1 ohm, replace FRONT FLOOD switch (para 2-28a).

Unscrew and remove cable connector from bottom of VEHICLE

Step 3.

LIGHTS switch.

Place main switch lever on VEHICLE LIGHTS switch in SER.

DRIVE position.

Connect ohmmeter leads to pins F and M of VEHICLE LIGHTS switch.

If ohmmeter indicates more than 0.1 ohm, replace VEHICLE

LIGHTS switch (para 2-28b).

2. FRONT BLACK OUT LIGHT INOPERATIVE

Unplug wire connector from front black out terminal. Set IGNITION

Step 1.

switch to ON position and place main switch lever on VEHICLE

LIGHTS switch in B.O. DRIVE position.

Connect positive voltmeter lead to vehicle ground.

a. If voltmeter indicates 24 Vdc, place IGNITION switch and

VEHICLE LIGHTS switch in OFF position and place bulb in

front black out light (para 2-30b).

b. If voltmeter does not indicate 24 Vdc, place IGNITION switch in

OFF position. reconnect wire connector to terminal on front

black out light, and proceed to step 2.