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 183 of 1015

TM 9-2320-272-24-1

Table 2-3. Electrical Troubleshooting.

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

ENGINE AND VEHICLE ELECTRICAL SYSTEM

1. ENGINE AND VEHICLE ELECTRlCAL SYSTEM MALFUNCTlONlNG

Test 1. Check alternator output.

Step 1.

Remove two screws (2), lockwashers (3), and terminal cover (1) from alternator (4).

Step 2.

Connect black test lead to ground and red test lead to lead 5.

Step 3.

Check alternator output (malfunction 9). Multimeter should indicate 26.5-29.5 volts.

Step 4.

If voltage is within range, go to step 6.

Step 5.

If voltage is not within range, adjust alternator (4). Perform malfunction 14.

Step 6.

Install terminal cover (1) on alternator (4) with two lockwashers (3) and screws (2).

Test 2. Check vehicle ground straps.

a.

Ensure ground straps are securely fastened and no paint is under starwasher.

b. Remove paint as necessary.

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