Relays are common components used in electronic and electrical circuits to control high-load devices. They are used in various applications, including automotive, industrial, and residential systems. One of the most common uses of relays is in starting a vehicle’s engine. In this article, we will discuss the 4 pin relay wiring diagram for the starter.
What is a Starter Relay?
A starter relay is a type of relay that is used to control the starter solenoid in a vehicle’s engine. The starter solenoid is responsible for engaging the starter motor, and the starter motor is responsible for turning the engine’s crankshaft to initiate the combustion process. The starter relay is typically located near the battery and is responsible for switching the high-current circuit that activates the starter solenoid.
What are the Components of a Starter Relay?
A starter relay typically consists of four pins or terminals. These pins are labeled as follows:
| Pin/ Terminal | Function |
|---|---|
| Pin 30 | Common (C) |
| Pin 85 | Control (Ct) |
| Pin 86 | Control (Ct) |
| Pin 87 | Normally Open (NO) |
The common (C) pin is the central pin and is typically connected to the high-current circuit. The control (Ct) pins are used to control the switching of the high-current circuit. The normally open (NO) pin is open when the relay is not energized and closes when the relay is energized.
4 Pin Relay Wiring Diagram for Starter
The 4 pin relay wiring diagram for the starter is shown below:
The wiring diagram shows the connections between the battery, starter motor, starter solenoid, and the starter relay. The four pins or terminals of the relay are shown as well.
How to Connect the Wiring?
Connect the wiring as follows:
- Connect pin 30 of the relay to the battery’s positive terminal using a 10-gauge wire.
- Connect pin 87 of the relay to the starter solenoid’s control terminal using a 14-gauge wire.
- Connect pin 85 of the relay to the ignition switch’s control terminal using a 14-gauge wire.
- Connect pin 86 of the relay to ground using a 14-gauge wire.
FAQs
What happens if the starter relay fails?
If the starter relay fails, the starter solenoid will not engage, and the engine will not start. The relay failure can be due to a faulty relay or a problem with the wiring or the starter solenoid.
Can I use a 5 pin relay instead of a 4 pin relay for starting a vehicle?
Yes, a 5 pin relay can be used instead of a 4 pin relay for starting a vehicle. The extra pin is typically used for a ground connection or an additional control function.
How do I test a starter relay?
To test a starter relay, you can use a multimeter to measure the resistance between the relay pins. The resistance should be low between pins 30 and 87 when the relay is energized. You can also use a jumper wire to bypass the relay and directly connect the battery to the starter solenoid to see if the engine starts.
Can a bad starter cause a relay to fail?
Yes, a bad starter can cause a relay to fail. If the starter is drawing too much current or is not engaging properly, it can cause the relay contacts to burn out or become stuck.
What is the difference between a starter relay and a starter solenoid?
A starter relay is a switching device that controls the activation of the starter solenoid. The starter solenoid is an electromechanical device that engages the starter motor and turns the engine’s crankshaft. The starter relay is typically located near the battery, while the starter solenoid is usually located on the starter motor.
