TM 5-3805-298-23-2
0142
Table 1. Rear Window Defroster Does Not Operate - Continued.
0142
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Test Step 6. Test for Voltage at Front
Rear Window Defroster
Work Light Relay.
Does Not Operate -
1. Turn ignition switch and battery
Continued
disconnect switch to OFF position
(TM 5-3805-298-10).
2. Remove defroster relay
(WP 0364).
3. Turn battery disconnect switch and
ignition switch to ON position
(TM 5-3805-298-10).
4. Press rear defrost switch to on
(momentary) (TM 5-3805-298-10).
5. Using digital multimeter
Voltage 18 to 28 V Replace lower cab
(WP 0174), test for voltage
wiring harness (WP 0291).
between connector C-C29
Proceed to Test Step 12.
(WP 0012, Figure 208) terminal 1
Voltage Less Than 18 V Proceed to
and terminal 5 (ground).
step 6.
6. Using digital multimeter
Voltage 18 to 28 V Proceed to Test
(WP 0174), test for voltage
Step 7.
between connector C-C29
Voltage Less Than 18 V Replace
(WP 0012, Figure 208) terminal 1
lower cab wiring harness (WP 0291).
and ground.
Proceed to Test Step 12.
Test Step 7. Test for Faulty Rear
Defrost Switch.
1. Turn ignition switch and battery
disconnect switch to OFF position
(TM 5-3805-298-10).
2. Disconnect connector C-C39
(WP 0012, Figure 210) from rear
defroster switch (WP 0012,
Figure 211).
3. Push and hold rear defroster
switch on (TM 5-3805-298-10).
4. Using digital multimeter
Resistance 5.0 Ohms or Less
(WP 0174), measure resistance
Proceed to Test Step 8.
between rear defroster switch
Resistance Greater Than 5.0 Ohms
(WP 0012, Figure 211) terminal 3
Replace defroster switch (WP 0364).
and terminal 2.
Proceed to Test Step 12.
Test Step 8. Test for Open at Lower
Cab Wiring Harness.
1. Remove left lower cab access
panels (WP 0347).
2. Remove transmission ECM cover
(WP 0266).
0142-4
