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 238 of 1015

TM 9-2320-272-24-1

Table 2-3. Electrical Troubleshooting (Contd).

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

29. TEMPERATURE GAUGE INOPERATIVE (COOLANT)

NOTE

If STE/ICE is available, perform NG31 - Gauge Test (para. 2-24).

Test 1. Test temperature gauge voltage. Perform malfunction 27.

Test 2. Test coolant temperature gauge sending unit.

Step 1.

Allow engine to cool.

Step 2.

Set multimeter to RX4 for resistance reading.

Step 3.

Disconnect lead 33 from temperature sending unit.

Step 4.

Start engine (TM 9-2320-272-10).

Step 5.

Connect multimeter negative lead to vehicle engine ground and connect positive lead to

sending unit terminal 33. The multimeter reading should decrease as engine

temperature increases.

If resistance does not show any decrease as temperature increases, replace temperature

sending unit (para. 3-93).

Test 3. Test lead 33 continuity.

Step 1.

Disconnect lead 33 from temperature gauge and temperature sending unit.

Step 2.

Attach temperature gauge end of lead 33 to chassis ground,

Step 3.

Set multimeter to RX1 for continuity reading.

Step 4.

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

unit end of lead 33. Multimeter should read continuity.

If continuity is not present, repair lead 33 (para. 3-131).

END OF TESTING!

2-150