How To: Install Engine Lid Fan

For those of you thinking about installing engine lid fans or those of you who have them and just aren’t sure how you want to go about wiring them this may be helpful. There are more than way wire you fan setup. The following way is how I chose to do it.

There are many fancy fan shrouds out there made of carbon fiber, polished aluminum etc. For my setup i used a simple 7.5 pusher spal fan. I tucked it up between the shroud and engine lid and used a heavy duty construction glue, drys clear and holds strong. You can pick the engine lid up by the fan and it holds fine. Looks very discrete and clean, the cheapest way to go. Very nice if your on a budget like myself.

How It Works: I chose to wire my fan directly to the Intercooler power wire, rather than to the relay. This way the engine lid fan will only come on when the engine temp sensor is tripped. Then I wired the IC fan (also a 7.5 spal fan) to the relay. Now when you turn the car on, the IC fan and engine lid fan both run once the engine heats up and trips the sensor.


  • 4 or 5 pin auto relay
  • inline fuse
  • wire connectors
  • 12-16ga wire
  • spal fan

Wiring: Now we are ready to begin setting up the relay. We will be using a simple 4 or 5 pin auto relay(with the 5pin you will not use the center pin). You can get them at radio shack for around $3. You will also need an inline fuse, some wire connectors, and a roll of 12-16ga wire. Everything should be purchased for under $15 minus the cost of the fan. I chose to remove the engine lid (5min) to mount the fan easier and hide the wire. You’ll need to extend the wires on the spal fan so that it can reach the ic fan wire plug and ground.

Using the following diagram you will set the relay up as followed:
1. TOP HORIZONAL – Attach wire from pin #1 to the ic fan
2. LEFT VERTICAL – Attach wire from pin #2 to a switched ignition wire. Easiest place is inside the fuse box located on the drivers side rear corner of the engine bay. Use a test light you’ll need to find a wire that is only hot when the ignition is on.
3. RIGHT VERTICAL – Attach wire from pin#3 to a ground.
4. BOTTOM VERTICAL – Attach wire from pin#4 to a wire that has constant power. Easiest place is in the same fuse box listed above. I also recommend you use and inline fue for this wire.

Now your relay is all connected and ready to go. The last thing you will need to do is ground the ic fans other wire. The one fan wire goes to the relay, stated above, and the other wire is the ground. To test the fan you can simply unplug the engine temp sensor located on the engine lid. Turn the ignition on and both fans, engine lid and ic, should kick on. Make sure they are both blowing air the right direction. If one or both fans are blowing the wrong way you just have the fan power and ground wires crossed.

This documentation in no way replaces the Toyota MR2 Repair Manuals. The purpose of this content is only to provide supplementary information to fellow MR2 enthusiasts. Midship Runabout and its contributing authors will not be held responsible for any injury or damages that may occur as the result of practicing any of the methods or procedures described within this website. Article and photo submissions are property of the contributing author.

You may also like...

Leave a Reply