Horn

Diagnose and replace a faulty horn or horn relay on a 1970 AMC Rebel Machine, including testing the horn button, wiring, and relay circuit.

Warnings

Tools required

Parts

• Horn (single or dual depending on original equipment) × 1 — Use OEM specification or aftermarket equivalent
• Horn relay × 1 — Standard 12V automotive relay
• Electrical connectors and terminals × 1 — As needed for repairs
• Wire repair sections (14-16 gauge) × 1 — As needed for damaged wiring

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery cable
3. Locate horn assembly mounted behind front grille or on radiator support
4. Locate horn relay typically mounted on firewall or inner fender panel
5. Obtain wiring diagram for reference if extensive troubleshooting is needed

Procedure

1. 1

   Initial diagnosis - test horn directly
   Reconnect battery temporarily. Using a test light or jumper wire, apply 12V power directly to the horn terminal while grounding the horn body to the frame. If horn sounds, the horn itself is functional and the problem is in the circuit. If no sound, horn needs replacement. Disconnect battery again before proceeding.
2. 2

   Test horn button circuit
   Remove horn button access cover on steering wheel center. Check continuity between horn button terminal and ground when button is pressed. The 1970 Rebel uses a ground-side switched circuit through the steering column. Clean contacts if corroded. If no continuity when pressed, horn button or slip ring assembly requires service.
3. 3

   Locate and inspect horn relay
   Find the horn relay mounted on the firewall or inner fender. On 1970 AMC models, this is typically a rectangular relay with four terminals. Check all wire connections for corrosion, looseness, or damage. Clean terminals with electrical contact cleaner and wire brush as needed.
4. 4

   Test horn relay operation
   With battery reconnected, use a test light to verify 12V power at the relay input terminal (typically marked as battery or 87). Ground the relay trigger terminal (typically connected to horn button circuit) manually with a jumper wire. Relay should click and horn should sound. If relay clicks but horn doesn't sound, check output circuit. If relay doesn't click, relay is faulty.
5. 5

   Remove and replace faulty horn relay if needed
   Disconnect battery negative cable. Note wire positions on relay terminals or mark with tape. Remove mounting bolt securing relay to firewall or fender (typically 7/16" or 1/2"). Disconnect all wires from relay terminals. Install new relay in reverse order, ensuring all connections match original configuration.
6. 6

   Access and remove horn assembly
   If horn replacement is needed, access horn from behind grille area. May require partial grille removal on some Rebel models - remove grille mounting screws if necessary. Disconnect electrical connector from horn. Remove horn mounting bracket bolt (typically 7/16") and remove horn assembly from radiator support or inner fender mounting location.
7. 7

   Install replacement horn
   Mount new horn to bracket or radiator support in same orientation as original. Ensure horn diaphragm faces forward and downward to prevent water accumulation. Tighten mounting bolt securely. Connect electrical connector ensuring clean, tight connection. The Rebel Machine may have dual horns - replace both if one has failed due to age.
8. 8

   Inspect and repair wiring if needed
   Trace horn circuit wiring from relay to horn and from horn button through steering column. Look for chafed, broken, or corroded wires. Pay special attention to areas where wiring passes through firewall grommets or near sharp edges. Repair any damaged sections using appropriate gauge wire and weatherproof connectors.
9. 9

   Test complete horn system
   Reconnect battery negative cable. Press horn button and verify horn sounds clearly and loudly. Check that horn stops immediately when button is released. Test multiple times to ensure consistent operation. If horn sounds weak or intermittent, recheck all ground connections and relay operation.

Reassembly

1. Reinstall grille components if removed during horn access
2. Secure all wiring away from hot exhaust components and moving parts
3. Reinstall horn button cover or steering wheel center cap
4. Verify no tools or parts left in engine compartment

Verification

• Horn should produce loud, clear tone when button is pressed
• Horn should stop immediately when button is released with no sticking
• No blown fuses or electrical issues after testing
• All mounting hardware secure and wiring properly routed
• Test horn operation several times to ensure reliability

More procedures for this vehicle