Ground Test

compliment could result in damage to the remaining

(2) Connect the leads of an ohmmeter to the

transistors.

g. Ensure that battery is charged to above 1.260

truck framework at two separate points where bare metal

is exposed. The ohmmeter should read zero ohm s.

specific gravity prior to any testing. Specific gravity

Caution: Use the battery receptacle

readings at 800F are as follows:

1.110 - 1.135 completely discharged

permanently mounted on the truck,

1.170 - 1.200 one-fourth charged

not the connector on the battery

1.205 - 1.230 one-half charged

cables from the battery.

1.235 - 1.260 three-fourths charged

(3) Leave the negative ohmmeter lead

1.265 - 1.290 fully charged

connected to the truck framework. Touch the positive

h. Check operation of replaced parts to ensure

lead to each terminal on the battery receptacle. The

trouble has been found.

ohmmeter must read 50, 000 ohms or more in each

i. Use the following test equipment or equivalent in

case.

addition to normal hand tools:

(4) Open the contactor unit. Touch the positive

(1) Volt-ohmmeter with 20, 000 ohms-per-volt

lead to either terminal of 400 ampere fuse Fl. (fig. 3-2.)

dc sensitivity.

The ohmmeter must read 50, 000 ohms or more.

(2) Peak-reading meter and shunt (50 mv, 500

(5) Place the directional control switch in

amperes ).

forward. Touch the positive lead to contactor unit

3-4. Ground Test

terminal 15. The ohmmeter must read 50, 000 ohms or

a. General. This test is made to assure that a short

more.

circuit does not exist between any part of the electrical

(6) Restore the directional control switch and

system and the truck framework.

disconnect the ohmmeter. Close contactor unit and

b. Procedure.

reconnect battery.

(1) Disconnect battery and discharge capacitors

3-3