Main Relay

Replace the main electrical relay on a 1970 AMC Rebel Machine, which controls power distribution to critical electrical systems.

Warnings

Tools required

Parts

• Main electrical relay × 1 — Use OEM specification or equivalent 12V automotive relay
• Dielectric grease × 1 — Small packet for electrical connections

Preparation

1. Park vehicle on level surface and engage parking brake
2. Turn ignition to OFF position and remove key
3. Disconnect negative battery cable and secure away from battery terminal
4. Allow engine to cool if recently running
5. Locate the main relay assembly on the firewall or inner fender well, typically near the voltage regulator or horn relay

Procedure

1. 1

   Test existing relay function
   Before removal, reconnect battery temporarily and use test light or multimeter to verify the relay is receiving power on the input terminal and that the relay is indeed faulty. Note wire positions and colors for reference. Disconnect battery again before proceeding.
2. 2

   Document wire connections
   Carefully note or photograph all wire connections to the relay. On 1970 AMC vehicles, the main relay typically has 4-5 terminals. Mark wires with tape if necessary to ensure correct reinstallation.
3. 3

   Disconnect electrical connections
   Remove all wire terminals from the relay. Most terminals are push-on spade connectors. Carefully pull straight off each terminal using needle-nose pliers if needed. Avoid twisting or bending the terminals.
4. 4

   Remove relay mounting hardware
   Remove the mounting screw or bracket securing the relay to the firewall or fender well. On most 1970 AMC applications, this is a single screw with a ground strap attached. Keep the ground strap for reinstallation.
5. 5

   Remove old relay
   Carefully remove the relay from its mounting location. Inspect the mounting area for corrosion or damage to the firewall or fender well mounting point.
6. 6

   Clean mounting area and terminals
   Use wire brush to clean the mounting surface and ground strap contact area. Clean any corrosion from wire terminals. Ensure good metal-to-metal contact for proper grounding.
7. 7

   Install new relay
   Position the new relay in the mounting location. Ensure the ground strap is positioned between the relay bracket and the firewall/fender mounting surface. Install mounting screw and tighten securely but do not overtighten to avoid cracking the relay housing.
8. 8

   Reconnect electrical terminals
   Apply a small amount of dielectric grease to each terminal on the new relay. Reconnect all wire terminals to their correct positions as documented earlier. Ensure each connection is fully seated and firm.
9. 9

   Verify connections
   Visually inspect all connections to ensure they are secure and properly seated. Gently tug on each wire to confirm solid connection. Verify no wires are pinched or touching hot engine components.

Reassembly

1. Reconnect negative battery cable to battery terminal and tighten securely
2. Ensure all tools and parts are removed from engine compartment

Verification

• Turn ignition to ON position (do not start) and verify electrical systems receive power
• Test operation of components controlled by the main relay including ignition system, fuel system, and accessories
• Start engine and verify normal operation of all electrical systems
• Check for any unusual electrical issues or blown fuses
• Listen for proper relay clicking sound when ignition is turned on

More procedures for this vehicle