Denso Relay 4 Pin Wiring Diagram

Denso parts are often used in Japanese assembled cars including cars manufactured by renowned brands like Toyota, Honda, Mitsubishi, Suzuki, Mazda, Daihatsu and several others. Relays are used to bypass signal wire and directly supply current from battery thus your car wiring remains safe from heating up and burning due to the load of heavy components. Relays are the integral component of any car wiring. No car wiring can be complete without these. These relays are usually found in fuse/relay boxes inside engine bay area or below the dashboard.

Whenever you have to install aftermarket accessories like HID, fog lamps, loud horns or fancy lights in your vehicle, make sure you check its power rating first. If it draws excessive current must install a relay to supply current directly from battery. Also install a fuse to make sure that short circuit would not cause the damage. Wiring a Denso relay is extremely simple. You just need to buy a separate relay harness to install it properly. The wiring diagram is given below to help you wire it properly. This wiring method is fully compatible with any 4 pin Denso relay starting with the serial number 156700 or look like the sample Denso relays below. We haven’t checked its compatibility with 5 pin Denso relays.

Wiring Diagram & Explanation:

1- Signal/Input: Connect positive wire coming from switch or button.
2- Supply ground to relay from body or negative (-) battery post.
3- Supply current from positive (+) battery post.
4- Output: Connect it with accessory or electrical component. This will supply current directly from battery.

> Make sure you have connected ground (-) of accessory or electrical component with body as well to complete the circuit.
> Relay will only function when you turn on the ignition or start the car and it receives the current from (1).

Safety: Wrong connection can cause short circuit or damage the relay. Avoid using very old relays removed from old fuse boxes as these can fail and cause trouble on the road. You can also purchase new Denso relays from auto parts store or online from Amazon, eBay or any other marketplace.