Now for the IC coolant pump wiring and mounting.

There are quite a few ways to wire the pump up, obviously you only want it on when you’d normally have the engine running (or when the key is turned to the “ON” position.) You could do this by using a fuse tap, but I’m not confident in the factory wiring to handle the added load of piggybacking off some other circuit. So I started studying the Toyota wiring manual and schematics and came up with the following.

61. In the main fuse box in the frunk, there is one large gauge wire that brings power directly from the battery. It is black with a thin green stripe. Like all the other fuse boxes, the power source is distributed to all the various fuses and relays on a metal strip or bar. I simply found a spot on the top side of the fuse box where I could solder a spade terminal to this bar. I also placed an inline fuse directly after this. This red wire will provide my constant on 12v for the pump. It runs out of the bottom of the fuse box just like the factory wires.

62. Now that I have a constant source of 12v, I need a conditioned signal wire to flip the relay. More studying of the wiring diagrams, and a lot of trial and error with a multimeter led me to the right wire. There is a signal wire leading from the box that turns on the power steering pump. This is a black wire with a red stripe. This wire produces 12v when the key is in the “ON” position. In the photo I have the bottom of the fuse box exposed, with the cover removed. You can see the wire tap I used to get the signal, which I sent to the relay using a yellow wire. You can also clearly see the heavy gauge black wire with green stripe I talked about earlier.

63. And here’s where those two wires run to. A simple single pole relay, which you can pick up at any auto store. The relay grounds out to the stock frunk grounding location (follow the black wire from the relay up and to the left.) The power (red) wire then runs down to the small cross-member and over to the pump. The additional wiring you see is for a set of Hella Supertones, more on that later.

64. This is the Bosch coolant pump mounted to the lower front cross-member. I used another T-bolt mount to hold it secure, bolted into the frame using some more rivet-nuts. The power wire is covered with sheathing, and the blue ground wire can be seen. You can also see how the hoses travel rearward tied off to the OE coolant hoses. Everything is tucked up above Corky’s MSMB as well.

more to follow….


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