Manual radiatior fan control

[chrisjunkie]

Hi All,

So thinking about putting in yet another switch so that I can force fans on (for a private grasskhana)

I was thinking, do I splice the wire from the ecu, add in a diode and on the other side of the diode have the manual switch? eg:

ECU --- DIODE --- Manual switch TEE --- wire to relay

The reason I ask is because if the ECU detects it has not gone low then it could cause a CEL?

ALSO, where should I be pulling power from? Currently I just pull straight off the battery but I want a switched circuit to use.

Have I confused anyone?? ;D

[Guest]

your fans will be working plenty fine without you needing to override it.

also, why would you want to force them off?

-smurff

[chrisjunkie]

 smurff said:

your fans will be working plenty fine without you needing to override it.

also, why would you want to force them off?

-smurff

Don't want to force them off, hence the reason for the tee. Only reason I'd want to force them on is I heard people turn their air con on the track but disconnect the actual aircon unit just to ensure that both fans are going for maximum air flow...

[Guest]

ahh its just you said force on/off lol, was like wtf is he thinking hahaha.

just for after track cooling, running both fans on a standard car wont do anything to ur time lol

tomorro if i remember to bring the laptop to work and no one has answerd you sence, ill see how the wiring is laid out.

-smurff

[Koom]

Fans are only really needed once you have slowed right down or become stationary (hopefully without wheels in the air).

Proper racecars don't have fans (they're just extra weight).

[Guest keltik]

On the H6, theres just a relay on the firewall above the air con pipes on the passenger side. It controls the fans and has 3stages. One fan, 2 fans low, and 2 fans on high speeds. Would be super easy to tee into it and control the fans manually

Surely the H4 has a similar setup? I dont think the fans have variable speed tho

On the track i just idle the motor for a bit then leave it stopped with the ignition on and the air con turned on. Both fans run at full tilt and that gets my underbonnet temps back down.

[chrisjunkie]

hmm thanks for the advice guys!

Prolly should have mentioned this in the first post, but I'm going to a grasskhana (sorry, already asked if clubsub could come and the answer was no ) so air flow wont really be happening

I will make a quick mock up in paint and you can let me know what you think.

Cheers

Chris

[Guest]

if its just for a one off, pop the bonnet, pull the fan relays, get a bit of wire with a switch and some blade fittings on each end and put that in there for the power to the fans between the contacts were the relay used lived, they will always run, did it for someone at a dragday, as the signal to there fan relay was stuffed. enough for them to carry on and get home.

-smurff

[Koom]

Ahh grasskana is a bit different. I was assuming it was for megameat.

I can see how fans on full blast would provide some piece of mind.

[chrisjunkie]

Yeah dont really want to blow up my new v7 sti engine

attached below is diagram as I was picturing it im my head:

[Guest boostin]

And check they're switched 12V, not switched to earth too.

[chrisjunkie]

yeah they are switched 12v i checked that. Might have to add in some pull down resistors too about 10 or 100k

[Guest boostin]

I would just run a wire from the fan control pin on the ECU up to a switch on the dash and then back to the fag lighter. None of this diode crap.

[chrisjunkie]

ecu wont mind the line being high when it shouldnt be?

[Guest]

The ECU switching is an earth. Ie the ECU provides an earth for the relay. So if you T in to the wiring for the fan relay. then earth the other side of the switch then that should work.

the power will be a switched 12volts as most ecus earth out the earth siginals for relays etc when the ECU is turned off. Link G4s etc do this.

[Guest]

 GETLOW said:

The ECU switching is an earth. Ie the ECU provides an earth for the relay. So if you T in to the wiring for the fan relay. then earth the other side of the switch then that should work.

the power will be a switched 12volts as most ecus earth out the earth siginals for relays etc when the ECU is turned off. Link G4s etc do this.

easy way

-smurff

[Guest boostin]

 chrisjunkie said:

ecu wont mind the line being high when it shouldnt be?

You'll find out soon enough. Its not my car. Lol.

[Guest keltik]

I had to move my car with the fan relay unplugged one day. It ran fine. Cant tell you if it tripped a check engine light tho as ive always got one.

[Guest boostin]

 keltik said:

I had to move my car with the fan relay unplugged one day. It ran fine. Cant tell you if it tripped a check engine light tho as ive always got one.

Or do you mean it never has one?

[Guest keltik]

Ah yes thats what i mean. It doesnt have one.....because the one it DID have refused to go out.