thermo fans. new TFS, having issues :(

**love ke70** · 23-02-2007, 09:55 PM

hey guys, i might get flamed for this thread but im at a dead end.
so ill try and explain the situation.
i had my thermo fans wired up using OC's method in this thread
http://forums.toymods.org.au/index.p...t=0#msg_469252
now, this worked fine, however the switch i was using was one that earthed when up to temp.
but wiring it just the way that diagram showed it worked fine. so i thought nothing of it.
this switch has however been switching on at 65 or so degrees and thus the fans running full time.
so i went and got a tridon switch today, 97 on 92 off. should work wonders.
however i installed and turn the key to the "ON" position and the fans come on.
unplug the wire from the switch, fans go off. so i think hmm, something weird.
check the sensor and it is earthed when cold.
so i do some net research and find yes, it is a normally closed switch.
sooo...
how do i solve my problem?
is it an issue with relays?
or have i fudged wiring?
or...
i dont know, throw something at me

just thought id add. the 5 pin relay im using has a diagram like this :

http://www.toymods.net/forums/attach...2&d=1144121063

and the 4 pin has no diagram.

ran a multimeter over the relays.

on the 5 pin, the two 87's are connected (surprise)
and the coil pins on each relay (85 + 86 i think) have something like 81 ohms resistance.
all of that was when no power applied.

anything else you need to know?
can you help, and let me love you

cheers, andrew

**takai** · 23-02-2007, 10:51 PM

You can run a DPDT relay which will switch between 87 and 87a when power is applied.
Hence when power is applied it will switch 30 to 87 and when power isnt applied it will go back to 87a

**RA35GT** · 23-02-2007, 11:23 PM

G'Day mate,

I've drawn a diagram to show you where your wiring is a little different to OC's. Essentially your 5 pin relay is not the same as OC's 5 pin relay. The 5 pin relay you have is a SPST relay with an extra connection to the output. This is why it works with your old temp sensor.

The 5 pin relay you want is a SPDT relay, this relay will have these terminals 30, 85, 86, 87a and 87. If you wire it as per OC's diagram again it should work.

See below for the wiring diagram, the diagram on the left is your current wiring, the one on the left is what it should be. You can see the difference in the relays.

http://members.reynolds.net.au/~poul...on%20Relay.gif

---Addded---I've drawn the relays in the condition it would be in when the engine is cold (before the switch trips).---Addedd---

Rudi

**BradW** · 23-02-2007, 11:45 PM

Wire it like this.

You can use your 5 pin relay for relay 1 but you will need a change over relay for relay 2.

**takai** · 23-02-2007, 11:57 PM

But he doesnt need 2 relays. You can just use a single DPDT relay for the switch, as when it gets to temp it will open. Ill draw a picture to make more sense.

EDIT: Picture addeds.
Edit2: and fixed.

**BradW** · 24-02-2007, 12:04 AM

Relay 1 is there to power the thermo from the battery rather than ignition. If you just use relay 2 and connect the 30 terminal to the battery, the fan will turn on when the ignition is turned off. You could over come this by connecting the 30 terminal to ignition but I wouldn't want the extra load on the ignition switch just to save one relay.

**takai** · 24-02-2007, 12:07 AM

Power 85 from ignition and 30 from battery.

**BradW** · 24-02-2007, 12:10 AM

His thermo switch is normaly closed, the same as Toyota thermo time switches. Your diagram will turn the fan on when the engine is cold and off when it is hot.

Edit: I apologise, your diagram is correct, however when the ignition is turned off the fan will turn on.

**takai** · 24-02-2007, 12:23 AM

Ergh, if i specified the switch type it would make more sense. That is a DPDT switch, and will be switched to 87 when power is applied and 87a when no power is applied.
Hence when power is applied to the relay (i.e. thermoswitch closed and engine cold) it will switch to 87 which has nothing attached to it. When the engine heats up and the thermoswitch opens, the relay will turn "off" and switch to 87a thereby activating the thermofan.

**BradW** · 24-02-2007, 12:31 AM

Originally Posted by takai

Ergh, if i specified the switch type it would make more sense. That is a DPDT switch, and will be switched to 87 when power is applied and 87a when no power is applied.
Hence when power is applied to the relay (i.e. thermoswitch closed and engine cold) it will switch to 87 which has nothing attached to it. When the engine heats up and the thermoswitch opens, the relay will turn "off" and switch to 87a thereby activating the thermofan.

Correct, and when the ignition is turned off, the relay will turn "off" and switch power to 87a thereby activating the thermofan

.

**love ke70** · 24-02-2007, 05:20 PM

IT WORKS!!!

thanks to all that helped.
i went brads way as at autobarn they had "normal" relays whatever type that may be
then they had the cross over type. so i went, ahuh, he said i could use one of them.
so bought that. wired it up.
works a treat. fans strruggle a little to bring temps down, but nothing too bad, and im not sure of the accuracy of the gauge. but all things are good

thanks guys