09/02/2025
This is a wiring diagram for a hidden starter enable button using two relays. This modification is typically done for anti-theft purposes or to add an extra layer of security to a vehicle.
Let's break down the components and their connections:
Components:
* 12V+ Ignition START: This is the 12-volt power source that is active only when the ignition key is in the "START" position.
* 12V+ Ignition RUN: This is the 12-volt power source that is active when the ignition key is in the "RUN" position (or on).
* Momentary Button: This is the hidden button that the driver will press to enable the starter circuit.
* Relay 1 & Relay 2: These are two standard automotive relays.
* 12V+ Starter: This is the wire that provides power to the starter solenoid.
* Ground: A connection to the vehicle's chassis ground.
Wiring Connections:
* Relay 1:
* Terminal 30: Connected to 12V+ Ignition RUN.
* Terminal 86: Connected to one side of the Momentary Button.
* Terminal 85: Connected to Ground.
* Terminal 87a: Not used in this circuit.
* Terminal 87: Connected to Terminal 30 of Relay 2.
* Relay 2:
* Terminal 30: Connected to Terminal 87 of Relay 1.
* Terminal 86: Connected to 12V+ Ignition START.
* Terminal 85: Connected to Ground.
* Terminal 87a: Not used in this circuit.
* Terminal 87: Connected to 12V+ Starter.
* Momentary Button:
* One side connected to Terminal 86 of Relay 1.
* The other side connected to Ground.
System Operation:
* Ignition RUN: When the ignition key is turned to the "RUN" position, 12V power is supplied to Terminal 30 of Relay 1. However, the circuit to the starter is not yet complete because Relay 2 is not activated.
* Momentary Button Press: When the driver presses the hidden Momentary Button, it completes the circuit to Terminal 86 of Relay 1, energizing the relay's coil.
* Relay 1 Activation: Relay 1 activates, closing the connection between Terminals 30 and 87. This sends 12V power to Terminal 30 of Relay 2.
* Ignition START: When the ignition key is turned to the "START" position, 12V power is supplied to Terminal 86 of Relay 2, energizing the relay's coil.
* Relay 2 Activation: Because Relay 1 is already activated (due to the button press), Relay 2 now has power at Terminal 30 and activates when the key is in the "START" position. This completes the circuit to the starter solenoid.
* Starting the Engine: The starter motor engages and cranks the engine.
* Button Release: When the driver releases the Momentary Button, Relay 1 deactivates. However, because the key is still in the "START" position, Relay 2 remains activated, allowing the engine to start. Once the key is released from the "START" position, the circuit is broken, preventing the starter from engaging again without pressing the button.
Key Observations:
* Security Feature: The hidden button acts as a security measure, preventing the vehicle from being started by someone who doesn't know the button's location.
* Relay Logic: The two relays work together to create the desired logic: the starter can only be engaged if both the button is pressed (Relay 1) AND the key is in the "START" position (Relay 2).
* Momentary Button: The momentary nature of the button press means it only needs to be pressed briefly to enable the starter circuit.
Additional Notes:
* This diagram is a simplified representation and may not show all the details of a real-world installation.
* It's crucial to use appropriately sized wiring and components for all connections.
* Consult a qualified electrician for any installations or modifications to your vehicle's electrical system.
This diagram is a valuable resource for understanding how to add a hidden starter enable button to a vehicle. However, it's important to have a good understanding of automotive electrical systems before undertaking this type of project. If you're not comfortable with electrical work, it's best to consult a professional.
