CJ3A: Data Plates & Electrical - The JeepsterMan

CJ3A: Data Plates & Electrical

Decoding CJ-3A: Data Plates and Electrical System 

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Data Plate Specifications:

  1. Serial Number Plate:

    • Location: Dashboard, typically near the driver's side.
    • Information: Displays the unique serial number for identification.
  2. Engine Number Plate:

    • Location: Attached to the engine block or firewall.
    • Information: Shows the engine number, a specific identifier for the CJ-3A.
  3. Body Data Plate:

    • Location: Mounted inside the glove box lid or on the dashboard.
    • Information: Provides details about body style, color, model, and manufacturing specifics.
  4. Transfer Case Data Plate:

    • Location: Attached to the transfer case.
    • Information: Specifies model, serial number, and gear ratios.
  5. Transmission Data Plate:

    • Location: Mounted on the transmission case.
    • Information: Reveals details about the transmission, including model, gear ratios, and manufacturing insights.
  6. Axle Data Plates:

    • Location: Found on the front and rear axle differential housing.
    • Information: Contains axle specifics such as gear ratios and manufacturing details.
  7. Willys-Overland Data Plate:

    • Location: Typically on the dashboard or glove box lid.
    • Information: Features the Willys-Overland logo and production date.
  8. Tire Pressure Data Plate:

    • Location: Near the driver's side door or on the glove box door.
    • Information: Guides recommended tire pressure for various driving conditions.
  9. Chassis Lubrication Data Plate:

    • Location: Usually near the driver's side door or on the glove box door.
    • Information: Offers insights into chassis lubrication points and intervals.

Electrical System Insights:

Distributor Insights:

  • Distributor Name: Delco-Remy Model 1112379
  • Voltage: 6-volt
  • Ignition System: Distributor, ignition coil, and distributor cap work together for efficient combustion.
  • Distributor Cap: Clip-on type, secures spark plug wires for precision ignition.
  • Distributor Rotor: Channels high-voltage pulses to spark plugs with precise timing.
  • Centrifugal Advance: Fine-tunes ignition timing based on engine RPM.
  • Vacuum Advance: Adjusts ignition timing based on engine load and conditions.
  • ID Tag Location: Typically on the side of the distributor housing.


  • Voltage: 6 volts
  • Amperage: 40-60 amps
  • Function: Charges the battery and powers electrical systems.
  • Drive: Belt-driven with the engine.
  • Voltage Regulator: External, often on the firewall or in the engine bay.

Starter Motor:

  • Type: Electric
  • Voltage: 6 volts
  • Amperage: Variable, usually 150-200 amps
  • Function: Cranks the engine for starting.
  • Mounting: Typically on the engine block, near the transmission bell housing.
  • Gear Type: Bendix drive gear engages the flywheel.
  • Solenoid: Integrated for seamless starter engagement.
  • ID Tag Location: Often on the starter housing or body.

Spark Plug & Wires:

  • Spark Plugs:

    • Type: Standard or Resistor-type (Refer to manufacturer's recommendations)
    • Heat Range: Tailored for the engine's requirements (Check manufacturer's specifications)
    • Gap: Typically 0.025 to 0.035 inches (Check manufacturer's recommendations)
  • Spark Plug Wires:

    • Insulation: Heat-resistant materials.
    • Core Type: Carbon-core, copper-core, or suppression-core (Check manufacturer's recommendations)
    • Resistance: Suppression-type wires to curb interference.

Wiring Harness:

This wiring harness forms the nervous system of your CJ-3A, ensuring seamless communication between various electrical components.

  • Material: Insulated copper wiring.
  • Function: Connects and routes electrical power to various components.
  • Insulation: Provides protection against electrical conductivity and environmental elements.
  • Location: Runs throughout the vehicle, typically routed under the dashboard and along the chassis.
  • Connectors: Various connectors for different components, ensuring secure electrical connections.
  • Color Coding: Different colors for different circuits, aiding in identification and troubleshooting.
  • Weather Resistance: Designed to withstand exposure to the elements but not fully waterproof.
  • Maintenance: Regular inspection for wear, damage, or exposed wires. Replace damaged sections as needed.


  • Speedometer: Central gauge, monitors vehicle speed.
  • Fuel Gauge: Indicates the gas tank's fuel level.
  • Oil Pressure Gauge: Monitors engine oil pressure.
  • Ammeter (Amperage Gauge): Measures electrical current flowing to and from the battery.
  • Temperature Gauge: Monitors the engine coolant temperature.
  • Voltmeter: Displays electrical voltage of the charging system.
  • Engine Warning Light: Illuminates for engine issues.
  • Choke Indicator Light: Indicates choke status.


  • Voltage: 6 volts
  • Type: Lead-acid
  • Capacity: Around 80 ampere-hours (Ah)
  • Terminal Type: Top-post terminals
  • Construction: Maintenance-free design with sealed cells.
  • Maintenance: Regular checks of water levels and ensuring clean, tight terminals.

For further insights into your CJ-3A, stay tuned for Part 5, where we explore clutch, transmission, and transfer case intricacies. For authentic parts and expert guidance, trust JeepsterMan to keep your CJ-3A running smoothly.

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