How to Wire a 5 Pin Automotive Relay. Pins 87/30/85/86/87a . Bosch Style. Fans / Fuel Pump / Lights

This is a how-to video for wiring a 5 pin Bosch-style Automotive relay. I’ve created an actual circuit for you to follow along with, and I explain how they work. Relays are important to have for Fuel Pumps, Electric Fans, Horns, Aftermarket Lights, etc. They protect the switch from damage by passing the higher amperage through the relay instead of the switch. In this specific diagram, it is wired as a "positive trigger" relay. That means that you are controlling the positive side of the circuit with a switch, rather than the negative side.

0:00 How to Wire a Relay
0:52 Pin 30 - Power goes into this from the battery.
1:05 Pin 87 - Power comes out of this and goes to your accessory with the switch ON.
1:23 Pin 86 - Power goes into this from the switch.
2:01 Pin 85 - Goes to ground.
2:15 Pin 87A - Power comes out of this with the switch OFF. It doesn't need to be used.
2:36 Relay Diagram Recap

How to Wire a Relay:

Pin 87 – Power will come OUT of this pin. This pin needs to be connected to the power side of your accessory (LED light, fuel pump, radio, etc.)

Pin 85 – This connects to ground. The chassis, body, negative terminal on battery should all work if they are already grounded properly.

Pin 87a – Power will come OUT of this pin when the toggle switch is turned OFF. This pin is not always needed and can be ignored if so.

Relays from the video:
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#RattyMuscleCar
#wiring
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#Automotivewiring

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[WiringRescue]

Thank You for Watching the Relay wiring video! 

[oritrond]

This is the BEST explanation on how to wire a relay that I have seen...I've watched a BUNCH of videos on how to do this. Thank you for putting this up. Well done!

[davidyoung]

Excellent video. Clear and concise with no annoying splash openings or music.

[maneateroftsavo]

You can tell how well someone understands a subject by how well they can simplify it... you sir have made relays (an intimidating subject) easy to understand to an average joe. Thank you!

[DavidSmith-swkg]

All I have is a relay in hand with no packaging.
It was given to me by a mechanic because I was burning up switches to the electric fan in my Jeep.
Laid out like a elementary school project makes all the difference in understanding.
Labeling the colors functions and placements is a blessing.
Thank you so much for your video.👍

[Sr_iRL]

Your way of showing us is as the older folks at the car shows would say: KiSS, Keep it stupid simple!
Subbed!

[jimmyflint]

Definitely the best explanation of a 5 pin relay . I’m tryna wire my DRL on my car like the Kia tellurides’ DRL.

[charlesterwilliams]

This by far is the best relay instructional on the internet. You are clear and to the point. Love the presentation. Your diagram or char was superb. For the first time I can say I now understand relays all thanks to your efforts.

[albertmichau]

The Best video, not 20 min long talking about birds and what... Great video and explanation THANKS

[TheFixerHomeRepair]

This is a fantastic explanation! And a very cool little display, so much easier to understand. Please keep this setup and put it in a shadow box in your garage!

[dennislecompte]

This is by far the best example I’ve seen. Thanks for making this so simple!!

[waynep]

I love it. I wire relays in as kill switches. Looking at the wiring diagrams for that car. Cutting into the power to the fuel pump from the fuel pump relay to pins 30 and 86. Pin 87 continues the circuit to the pump. Pin 85 goes to the hidden switch, the other side of the switch is hooked to ground.
On some I use 87A to power a horn under the drivers seat so if the ignition is turned on with the kill switch off the horn under the drivers seat goes off. I normally try to get the 130db horns from the cheap tool store.

[MKlukowski]

Jawdroppingly simple yet informative. A 4 minute video on something that would be extended to 1, 5 hours in school (if even taught)

[dallas]

I can’t believe I actually kind of understood this. I’ve been having such a hard time. Thanks

[Samualninja]

After watching a few boomers try to say it's 2 circuits that require 2 power sources, I'm glad to have stumbled across your video which confirms my suspicion that it can SIMPLY from the same power source.
The video is SO simplified compared to others and well laid out. Can't wait to put it to practice.
Cheers mate!

[oterwill]

Incredibly helpful for applying to exactly the application I was looking for! And echo those who have said it's one of the best and clearer explanations out there!

[gowithem]

If you can’t explain relay like this guy, it means you don’t understand what a relay is

[EndoftheRd]

so far the best explanation hands down all over the youtube .
thank you soo much VERY detailed video friend, you must be someone off the chain being so committed for your viewers

[testorossa]

I virtually never leave reviews but I logged in and everything because this video is that great. Amazing explanation thank you so much for explaining the missing pieces that everyone leaves out.

[lionridds]

Best video I've seen by far! Simple, concise and clear!