The two main power cables:
* Large, Positive (+) Cable: This thick, heavy-gauge cable carries the high current needed to crank the engine. It connects to the large terminal stud on the starter motor itself. This stud is usually very clearly the biggest and most prominent terminal. This cable runs to the positive (+) battery terminal (directly or through a relay/solenoid).
* Large, Negative (-) Cable: This cable isn't directly connected to the starter itself. The engine block acts as a ground for the starter motor. This cable connects from the engine block to the negative (-) battery terminal. This completes the circuit and allows the current to flow.
The smaller wire (sometimes present):
* Small Wire (Control Circuit): This smaller wire connects to the smaller terminal on the starter solenoid. This is the terminal that engages the starter motor. This wire is controlled by the ignition switch, so when you turn the key, power is sent to this terminal to activate the starter. Sometimes this wire goes directly to the ignition switch, other times it goes through a relay.
Caution:
* Always disconnect the battery's negative (-) terminal before working on any electrical components. This prevents accidental short circuits and shocks.
* Double-check your wiring against a diagram specific to your vehicle's year and model. While the general principles are the same, slight variations can exist. You can find wiring diagrams in repair manuals (Chilton's, Haynes, etc.) or online.
* Improper wiring can damage your starter, battery, or even cause a fire. If you are unsure about any part of the process, it is best to consult a qualified mechanic.
In short, you'll find one large positive cable going to the big terminal on the starter, a ground cable attached to the engine block, and possibly a smaller wire connected to a smaller terminal on the starter solenoid. Always refer to a wiring diagram specific to your vehicle to ensure you have the correct connections.
