The starting system used in the Ford Falcon XK is designed to crank the engine at a sufficient speed to allow it to start. The system converts electrical energy from the battery into mechanical rotation through the starter motor.
The starting system consists of several major components working together:
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Starter motor and starter drive assembly
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Vehicle battery
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Remote control starter relay or solenoid
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Ignition switch starter circuit
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Heavy electrical wiring
When the ignition key is turned to the start position, electrical current flows through the starter control circuit to energise the starter relay. The relay then closes the high-current circuit between the battery and the starter motor, allowing the starter motor to rotate and crank the engine.
Starting System Circuit Operation
The starter circuit uses both a control circuit and a high-current circuit.
The control circuit activates the starter relay or solenoid, while the heavy current circuit supplies electrical power directly to the starter motor.
When the ignition switch is turned to the start position:
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The starter switch closes the starter control circuit.
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Current flows through the starter relay coil.
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The relay contacts close.
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Heavy battery current flows to the starter motor.
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The starter motor rotates the engine crankshaft.
This operation continues until the engine starts and the ignition key is released from the start position.
Automatic Transmission Neutral Safety Switch
Vehicles equipped with automatic transmission include a starter neutral safety switch within the starter control circuit.
This safety device prevents operation of the starter motor unless the transmission selector is placed in either:
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Neutral (N)
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Park (P)
The neutral safety switch prevents accidental vehicle movement during starting.
Adjustment procedures for the neutral safety switch are described in the transmission service section of the workshop manual.
Starter Circuit Schematic
The starting system schematic diagram illustrates the electrical connections between the major components of the starting circuit.
Key components shown in the circuit include:
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Battery
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Starter relay
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Starter motor
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Ignition coil
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Starter switch on the ignition switch
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Neutral safety switch (automatic transmission models)
The schematic helps technicians understand the path of electrical current during starter operation and assists in diagnosing faults within the starting system.
Starting Circuit Testing
Testing the starting circuit involves checking the electrical path between the battery and the starter motor to ensure that all switches, relays and wiring connections operate correctly.
Typical testing procedures involve:
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Checking battery voltage and battery cable connections
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Inspecting the starter relay operation
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Verifying the ignition switch starter circuit
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Testing the neutral safety switch function on automatic transmission vehicles
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Checking continuity through the starter control circuit
A schematic test diagram can be used to trace the current path and identify open circuits or faulty components within the system.
Starting System Fault Diagnosis
If the engine fails to crank or cranks slowly, the fault may originate from several possible causes including:
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Weak or discharged battery
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Faulty starter relay
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Defective ignition switch starter circuit
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Poor electrical connections
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Faulty neutral safety switch
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Worn starter motor components
Careful diagnosis using the circuit schematic and testing procedures allows the faulty component to be identified and repaired.
Safety, Copyright and Source Notice
Safety Disclaimer
Working on motor vehicles involves mechanical, electrical and chemical hazards. Always ensure the vehicle is safely supported, the engine is switched off when appropriate, and suitable safety equipment such as gloves and eye protection are used. If you are unsure about any repair or maintenance procedure, consult a qualified mechanic before attempting the work.
Source
Information compiled from period factory service literature.
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