TM
9-2320-363-20-1
Table
3-1.
Troubleshooting
(Cont)
Malfunction
Test
or Inspection
Corrective
Action
ELECTRICAL
SYSTEM
(CONT)
Electric
Horn
Circuits
(Cont)
1.
ELECTRIC
HORN
DOES
NOT
OPERATE.
Step
1.
Step
2.
Step 3.
Step
4.
Step 5.
Step
6.
Step
7.
Step 8.
Check
horn 15A fuse.
.
if defective,
replace
15A fuse (page
4-204).
Check for +12 VDC
at lead 420JD
from auxiliary
light power bus.
.
If +12 VDC
is present,
go to step 3. If no voltage is present,
repair lead 420JD
(page
3-2).
Disconnect
horn relay from connector.
Check for +12
VDC
at connector 30.
l
If +12 VDC
is present,
go to step 4. if no voltage
is present,
repair lead 24 (page
3-2).
Disconnect
horn relay. Check for +12 VDC
at connector
85.
.
If +12 VDC
is present,
go to step 5. If no voltage
is present,
repair lead 24 (page
3-2).
Disconnect
lead 25 from horn button. Check for +12 VDC
at lead 25.
l
If +12 VDC
is present,
go to step 6. If no voltage
is present,
replace
horn
relay
(pages
4-197,
4-198).
Disconnect
ground
lead
from
horn
button.
Check
for continuity
between
ground lead and ground.
.
If continuity is indicated,
go to step 7. if no continuity
is
indicated,
repair
ground
lead
(page
3-2).
Disconnect
lead
25
from
horn
button.
Press horn switch. Check for
continuity
between
switch
contacts.
.
If continuity is indicated,
go to step 8. if no continuity is
indicated,
replace
horn button (page 4-606).
Disconnect
lead 26 from horn. Check
for +12 VDC
at lead 26 with horn
button pressed.
.
If +12 VDC
is present,
go to step 9. If no voltage
is
present,
disconnect
horn
relay
and
check for continuity between
connector 87 and lead 26.
If continuity is indicated,
replace
horn relay (pages
4-197,
4-198).
If no continuity
is indicated,
repair lead 26 (page
3-2).
3-53
