p/n: 113E-13800B
Non-polarity sensitive horns are isolated mounted to a bracket spot welded to the inner fender. Activated by a spring loaded switch to ground on the turn signal.
Servicing:
Decibels can be increased by turning the square head tone adjuster screw either CW or CCW. These horns are sensitive to a slight variation of voltage. If your car is equipped with a generator and the engine is idling with a load i.e lights on, there will be a voltage drop across the horns resulting low DB power.
To solve that issue, install a 20 amp relay near the horns.
Inoperative horns: Drill-out the aluminum ribbed neck rivets. Separate the two halves carefully. The diaphragm / plunger assembly and circuitry should be in good condition. Slight rusting is acceptable. Clean diaphragm and inner unit with steel wool and WD-40. Check insulation material and rivets. Clean contacts with a nail file. Remove the tone adjuster screw and check to see if the screw end did not wear through the installation thus causing the screw ground to the metal flap. If it has, glue a 1/2"x1/2"x1/16" thick fiberglass type material to the adjustment pad.
Continuity Check:
Lo Horn: FG6 terminal #1 not grounded to housing.
terminal #2 not grounded to housing.
Coil check across terminal 1 and 2 approx. 120K ohms
Hi Horn: FG9 terminal #1 not grounded to housing.
terminal #2 not grounded to housing.
Coil check across terminal 1 and 2 approx. 130K ohms
Testing:
Install diaphragm / plunger into coil cavity. Hold down center of diaphragm while momentarily applying 12 V to the terminals. Unit will react as a solenoid.
Assembly:
Replace paper gaskets as needed. Install diaphragm / plunger and attach horn housings. Install rivets machine screws, or such. ( I used 1/4" - 28 x 1/2" long ribbed neck carriage bolts with nuts for easy future access. You would need to increase the size of the holes to accept the ribbed neck bolts).
Install tone adjuster screw until it just touches the pad. Horn contacts are closed. Turning the tone screw CW until the contacts just open. Check this by a ohm meter probe on one terminal and the other probe
on the casing. Mounting the horns directly to the bracket without insulating and the contacts are closed will cause the horn to activate with only one hot wire to the terminal.
Testing:
Attach hot wire to the horn terminal and intermittently touch the ground wire to the other terminal while turning the tone screw CW slowly until the decibels is at max. At that point, there should be no continuity between each terminal to the base of the horn. The horns can be mounted either insulated or not.
