
TROUBLESHOOTING AND ELECTRICAL SYSTEM
Test Procedures
Page 11-52
2005 FE350 Gasoline Vehicle Maintenance and Service Supplement
11
TEST PROCEDURE 40 – VOLTAGE AT HORN
See General Warning, Section 10, Page 10-1.
1. Disconnect the battery cables as instructed.
See WARNING “To avoid unintentionally starting...” in
General Warning, Section 10, Page 10-1.
2. Remove the center dash assembly.
See Key Switch Removal, Section 12, Page 12-13.
3. Remove the mounting nut from the front of the horn mounting bracket.
4. Disconnect the 18-gauge orange wire from the horn terminal and remove the 18-gauge black wire from
the horn mounting stud.
5. Using a multimeter set on 20 volts DC, place an alligator clip on the black (–) probe. Connect the black
(–) probe to the 18-gauge black wire ring terminal. Place the red (+) probe into the spade terminal on the
orange wire
(Figure 11-56, Page 11-52)
.
See following CAUTION.
ý
CAUTION
• Before connecting battery cables, make sure no terminal ends or probes touch each other, the
front body trim, or other parts of the vehicle frame. If they do, it could blow the fuse or cause
wire damage.
6. Connect battery cables, positive (+) cable first, and tighten hardware to 12 ft-lb (16 N·m).
7. The reading should be zero volts.
8. Press the horn button. The reading should be approximately 12 volts.
9. If the readings are incorrect, check the continuity of the wires, the horn button, and fuse. If the readings
are correct, replace the horn.
Figure 11-56 Horn Circuit Test
Figure 11-57 Horn Button Test
16-GAUGE BLACK
HORN GROUND WIRE
16-GAUGE ORANGE
WIRE
HORN
2m
20
m
200
m
2k
200
200
200
200
20
2
200
m
500
20k
200k
2000
k
1000
OFF
WAVETEK
5XL
V
V
V
A
!
!
COM
200nA
MAX
1000 ---
750V
FUSED
20 VDC
SETTING
HORN BUTTON
2m
20
m
200
m
2k
200
200
200
200
20
2
200
m
500
20k
200k
2000
k
1000
OFF
WAVETEK
5XL
V
V
V
A
!
!
COM
200nA
MAX
1000 ---
750V
FUSED
200 OHM
SETTING