TM-9-2320-272-24-1

TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)

TECHNICAL MANUAL; UNIT, DIRECT SUPPORT, AND GENERAL SUPPORT MAINTENANCE MANUAL; VOLUME 1 OF 4

JUNE 1998

TM-9-2320-272-24-1 - Page 220 of 1015

TM 9-2320-272-24-1

Table 2-3. Electrical Troubleshooting (Contd).

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

21. REAR LIGHTS INOPERATIVE

Test rear lamp connector voltage.

Step 1.

Place battery switch to OFF position.

CAUTION

Step 2.

Step 3.

Step 4.

Step 5.

Step 6.

Lead 15 or wire 15 is hot whenever the batteries are connected.

Disconnect lead wire corresponding to inoperative rear lamp.

Place battery switch to ON position.

Place light switch to position corresponding to disconnected lead wire.

NOTE

For stoplight lead test, brake pedal must be depressed and air

pressure maintained.

Set multimeter to 50-volt range.

Connect multimeter negative lead to vehicle chassis ground and positive lead to

disconnected lead wire. Light switch must be in the corresponding position. Note voltage

indication.

a. If voltage was indicated, replace bulb (para. 3-118). If new bulb fails to operate,

perform malfunction 16, test 2.

b.

If battery voltage is not indicated, perform malfunction 16, test 4.

2-132