ENGINE DOES NOT REACH OPERATING TEMPERATURE

TM 9-2320-285-24-1

2-11. COOLING SYSTEM TROUBLESHOOTING (CONT)

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

2. ENGINE DOES NOT REACH OPERATING TEMPERATURE

Step 1.

Disconnect thermal switch lead at thermal switch (para 2-15e). Turn key switch to on position.

Momentarily connect thermal switch lead to thermal switch; an audible click should be heard at solenoid,

indicating proper operation.

a. If audible click is heard, go to step 3 below.

b. If audible click is not heard, go to step 2 below.

Step 2.

With key switch turned to on position, use a voltmeter to check for 12 Vdc at both terminals of thermal

switch.

a. If voltage is present at both terminals, go to step 3 below.

b. If voltage is not present at one terminal, go to step 4 below.

c. If voltage is not present at either terminal, notify direct support maintenance.

Step 3.

With key switch turned to off position, check continuity of solenoid using an ohmmeter: disconnect

ground wire from alternator (para 2-24) and unplug connector above left hand valve cover (para 2-15e).

a. If continuity is not obtained, replace solenoid (para 2-15e).

b. If continuity is obtained, go to step 5 below.

Step 4.

With engine temperature below 180 degrees F, connect ohmmeter across thermal switch terminals

(thermal switch lead remains disconnected at thermal switch.) Ohmmeter should indicate zero ohms

with engine cool. Start engine and watch WATER TEMP gage; when gage indicates 195 degrees F,

ohmmeter should indicate open circuit (infinity).

a. If ohmmeter does not indicate zero ohms when engine is cool, or does not indicate open circuit

(infinity) when WATER TEMP gage indicates 195 degrees F, replace thermal switch (para 2-15e).

b. If ohmmeter indicates zero ohms when engine is cool, and indicates open circuit (infinity) when

WATER TEMP gage indicates 195 degrees F, disconnect ohmmeter from thermal switch and

reconnect thermal switch lead (para 2-15e). Then go to step 7 below.

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