Horn System Diagnosis And Repair - Jeep 1979 CJ-5 Technical & Service Manual

3S-1
HORN
SYSTEMS
SECTION INDEX
Page Page
General 3S-1
Horn System Dlangosls mi Repair
3S-1
Horn Ad|ustment 3S-2 Specifications 3S-2
GENERAL
The horn circuit includes horn(s), horn relay, battery,
steering column wiring harness, horn ring, and the body
sheet metal.
A cadmium-plated ground screw is used to attach the
horn(s) to the body. Do not substitute other types of
ground screws as they may become corroded and cause a
loss of ground.
To reduce the current flow through the horn ring
contacts, a relay is used between the battery and horn.
The horn relay consists of an electromagnet and a set of
contacts arranged so that when the magnet is energized
an armature is attracted and the contacts close. A spring
keeps the contacts open when the unit is at rest. The
horn-ring contacts carry only relay current, while the
relay opens and closes the circuit between the horn and
battery (fig. 3S4).
RED W/T
HORN
TO M A I N
HARNESS
CONTACT
1 B L A C K W/T
8 0 2 6 4
Fig 3S-1 Horn Circuit Schematic
A fusible link is incorporated in the main wiring har-
ness to furnish protection against major harness
damage.
When a grounded circuit or overload occurs in the
horn circuit, damage will be limited to the fusible link.
HORN SYSTEM DIAGNOSIS AND REPAIR
In case of horn system failure, proceed as follows:
(1) Using a test light or voltmeter, check for battery
voltage in the red lead to relay before individual com-
ponents are tested or replaced.
(2) A lack of voltage indicates fusible link or har-
ness is open and cause of failure must be determined
and repaired prior to installing a replacement fusible
link or other components.
(3) The replacement fusible link is supplied in the
proper length with a terminal connector on one end.
(4) Inspect wiring between horn, relay and battery
for loose connections, faulty insulation, corroded termi-
nals, or improper ground connection at horn base.
(5) If horn does not operate when ring or button is
depressed, ground number 2 terminal (fig. 3S-1) of horn
relay with a jumper lead. If horn operates, this indicates
proper operation of horn and relay.
(6) Inspect horn ring switch and wire from switch
to relay carefully for source of trouble.
C A U T I O N : Do not ground red lead.
(7) If horn does not operate, ground number 2 ter-
minal and connect a jumper lead from horn relay termi-
nals 1 to 3.
(8) If horn now operates, a faulty horn relay is
indicated.
(9) If it does not operate, check wiring and con-
nections between the horn relay terminal number 3 and
horn for continuity.
(10) Connect a jumper lead from horn base to the
vehicle chassis or engine and repeat the above tests.
(11) If horn now operates, remove attaching screw,
horn and mounting bracket, clean mating surfaces.
(12) Install horn, mounting bracket and attaching
screw, tightened screw to 15 foot-pounds (20 N»m)
torque.
(13) If horn still does not operate, horn is inoperative
and must be replaced.