Using the stock fan wiring with a standalone

[DaveSmed]

Had a bit of an obstacle when I went to wire in my DTA to my stock fan wiring, the DTA provides a ground to turn on a relay, and the factory setup uses a positive trigger.



Looking at terminal 85 of K1 and K6, there is a ground through the fuse box circuit board of K1 only. K6 has a wire jumping it to pin 3 of C114 for a ground.

I was able to cut the jumper, and wire that into the lead from C101 that I used for my fan trigger. I then just cut the black/brown wire from terminal 86 and connected that to C100 with a ring terminal.

Now the DTA can control whatever is wired to the high speed relay, and the radiator mounted switch can control what is wired to the normal speed relay as kind of a fail safe.



Thought it might help somebody.....

[LowR3V'in]

Thanks for the post. I'll be doing this next.

[e30leigh]

so in other words you have fully removed your a/c system from the car?
if you still run a/c this will not work for people.

and other means will need to be used if you want to run an electronic cooling fan, such as temp control swithes or ecu controlled systems to switch the fan on or off.

[Jaxx_]

i bypassed my temp switch all together because they had failed, and then just have megasquirt control a low output for the aux fan on the K6 relay pin 85, and bend the relay pin and wire up a female spade connector. You don't have to modify the existing vehicle wiring except to jumper the thermo switch wire.

I wasn't totally sure how you explained how you did yours, mainly with the c100...?

[DaveSmed]

so in other words you have fully removed your a/c system from the car?
if you still run a/c this will not work for people.

and other means will need to be used if you want to run an electronic cooling fan, such as temp control swithes or ecu controlled systems to switch the fan on or off.

No I have not. The A/C still feeds K1 through the diode and works as factory.

Rereading what I wrote, I should have been a bit clearer in my post that i'm using the standalone output to control the fan, not some accessory.

i bypassed my temp switch all together because they had failed, and then just have megasquirt control a low output for the aux fan on the K6 relay pin 85, and bend the relay pin and wire up a female spade connector. You don't have to modify the existing vehicle wiring except to jumper the thermo switch wire.

I wasn't totally sure how you explained how you did yours, mainly with the c100...?

You basically did the same thing. Instead of feeding the relay power through the whole thermo switch circuit that is not used by jumping it at the switch, I stole power from the underside of the fusebox. C100 is that allen bolt between K3 K4 K7 and K8. It is where the main connection to the battery is made to the fusebox, and a handy source of power for this project and the yellow wire coming out of K4 that goes into K5 for keeping your high beams on with your lows.

Instead of bending the relay pin up and having a wire coming out of the fusebox, I nabbed it using the factory fusebox terminals and connected to it underneath. Very clean, factory look.

[Jaxx_]

You basically did the same thing. Instead of feeding the relay power through the whole thermo switch circuit that is not used by jumping it at the switch, I stole power from the underside of the fusebox. C100 is that allen bolt between K3 K4 K7 and K8. It is where the main connection to the battery is made to the fusebox, and a handy source of power for this project and the yellow wire coming out of K4 that goes into K5 for keeping your high beams on with your lows.

Instead of bending the relay pin up and having a wire coming out of the fusebox, I nabbed it using the factory fusebox terminals and connected to it underneath. Very clean, factory look.

ah, okay. That sounds good. I didn't mess with it because it's simply a race car and i didn't care how it looked. :up:

[nando]

you could also use a transistor to invert the signal, and leave the wiring stock.. :)