Starter Solenoid

Replace or diagnose the starter solenoid on a 1970 AMC Rebel Machine with 390ci V8 engine to restore proper starter motor engagement.

Warnings

Tools required

Parts

• Starter solenoid (compatible with AMC 390 V8 starter) × 1 — Use OEM specification or aftermarket equivalent for 1970 AMC
• Battery terminal cleaner and protector × 1 — Anti-corrosion spray

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery cable and secure away from battery post
3. Allow engine to cool if recently operated
4. If needed for better access, raise front of vehicle and support on jack stands
5. Clean battery terminals and starter area of dirt and corrosion

Procedure

1. 1

   Locate starter assembly
   Position yourself under the right side of the engine. The starter motor is mounted on the passenger side of the engine block, near the bellhousing. The solenoid is the cylindrical component mounted on top of the starter motor housing.
2. 2

   Document wire connections
   Before disconnecting any wires, note or photograph the wire positions on the solenoid. The solenoid typically has two large terminals (battery cable and starter motor cable) and one or two small terminals for the ignition switch trigger wire.
3. 3

   Disconnect battery cable from solenoid
   Using a 9/16" wrench, remove the nut securing the positive battery cable to the large solenoid terminal. This is typically the terminal closest to the battery. Carefully move the cable aside to prevent it from touching any metal surfaces.
4. 4

   Disconnect starter motor cable
   Remove the nut from the second large terminal which connects to the starter motor itself. This cable is usually shorter and connects the solenoid output to the starter motor.
5. 5

   Disconnect trigger wire
   Remove the small wire(s) from the small terminal(s) on the solenoid. This is the wire coming from the ignition switch (often purple or purple/yellow on AMC vehicles). Note the terminal position for reinstallation.
6. 6

   Remove solenoid mounting hardware
   Locate the two mounting screws or bolts that secure the solenoid to the starter motor housing. These are typically located on the solenoid mounting flange. Remove these fasteners using the appropriate socket or wrench. On some units, these may be Phillips head screws or hex bolts.
7. 7

   Remove old solenoid
   Carefully pull the solenoid away from the starter motor housing. The solenoid plunger will disengage from the shift lever inside the starter. You may need to rotate or angle the solenoid slightly to clear any obstructions.
8. 8

   Inspect shift lever and plunger
   With the solenoid removed, inspect the shift lever mechanism inside the starter nose housing. Check for wear, damage, or binding. Clean any dirt or corrosion from the plunger contact area. This is a good opportunity to verify the starter drive gear is not damaged.
9. 9

   Install new solenoid
   Position the new solenoid so the plunger engages with the shift lever fork inside the starter housing. Align the mounting holes and ensure the solenoid seats flush against the mounting surface. Install and tighten the mounting fasteners securely.
10. 10

    Reconnect starter motor cable
    Attach the cable running to the starter motor to the appropriate large terminal on the new solenoid. Install the nut and tighten securely. Ensure the connection is clean and tight to prevent voltage drop.
11. 11

    Reconnect battery cable
    Attach the positive battery cable to the battery input terminal on the solenoid (typically marked BAT or +). Install the nut and tighten securely with a 9/16" wrench. This connection carries high current and must be very tight.
12. 12

    Reconnect trigger wire
    Attach the small trigger wire from the ignition switch to the small terminal on the solenoid. Ensure the connection is secure. If there is a second small terminal for a bypass circuit, ensure any additional wires are properly connected.

Reassembly

1. Verify all electrical connections are tight and properly routed away from exhaust components
2. Ensure no tools or loose hardware remain in the engine compartment or under the vehicle
3. If vehicle was raised, lower it from jack stands safely
4. Reconnect negative battery cable to battery and tighten securely

Verification

• Turn ignition key to START position briefly - starter should engage smoothly without grinding or clicking
• Engine should crank at normal speed without hesitation
• Verify no smoke or burning smell from starter area during cranking
• Check that starter disengages immediately when key is released from START position
• Test start the engine 2-3 times to confirm consistent operation
• Inspect all connections for signs of arcing or overheating after testing

More procedures for this vehicle