HOW TO: Do it Yourself: Fan override switch

[jazzman]

Ok, since the caspers system won't work on my car i went out searching for different ideas, my number one concern was to not throw a code of somesort, and overall reliability, so while surfing jbody.org one day i found this handy little segment on how to do this mod, Its cheap and works, great, again, If I could use the caspers setup I would, but it won't work for my year.

So if your short on cash and want this mod, here are directions for you.

Fan override switch directions (http://www.j-body.org/library/howto.php?1)

Derek

[Scooter]

The only change I'd make to these instructions is to tap into an Ignition switched 12v wire (Pink 12ga in ignition harness) and not the B+ constant. If you have it tapped into the constant and forget to turn the fans off I hope you have jumper cables handy.

[AaronGAGT]

hey derek.. you got any pics?

[jazzman]

not yet, i'm doin it tomorrow

Derek

[GAGT7386]

Will this work on my 2001 GAGT? Sounds like a nice cheap way to have mod my fans in my car.


Trason

[coupe]

Trason trust me its worth it to buy it from caspers. VERY VERY VERY easy install.

[bsorensen]

newbie question.....but what exactly is a casper system?
does it allow you to use your fans without having the ignition turned on?

[PACE]

^ Yes. Fans on anytime at the flip of a switch.

[jazzman]

trust me it was really easy , i'll hopefully have pictures this weekend works great and it cost me a total of about 10 dollars.

Derek

[magyver]

this is scary, i was just thinking of doing this myself... personaly, i think caspers switch is way to damn expensive, i can do this w/ what i have laying around in my tool box, the only thing id do differnt than jazzman is id use a 3 way switch, use the center pin going to the fan, the top pin going to +12 and the other pin going to the original power wire to the fan.. w/ the use of a relay of course, but still, when toggle up, runs when you want too, when down, runs when the comp wants too... i bet i could install that in = to or less than caspers switch... but, thats me being cheap....

nice job jazzman, and stop thinkin like me.. its scary..

[GAGTSCTGuy]

Did anyone ever do this? How did it work out?

[abusedgt97]

Are they talking about using the factory relay?

If not why would you not just add an extra relay and tap into the fan wire?

[GAGTSCTGuy]

Thats what the directions say to do, but since they are for a j-body, I wasn't sure they wiring was the same.

[jazzman]

I did it and it works great

Derek

[Pvt_Murphy]

I've done a similar mod to my friend Focus and will prolly do the same on my car.
Because I first did this when his temp sensor was borked there are a few versions:
here's a few of the configurations I did:

easiest to use crimp on spade connectors.

1) To just them always on when the car is on, I pulled the relay, and ran a wire from the + 12v terminal of the to Vout terminal going to the fans. (quick fix w/ 6" of wire if you ever need a temporary solution)

2) To have manual only control: ran wire from +12v from relay terminal to switch mounted inside the car to Vout terminal going to the fans back to the relay socket.

3) To have manual or PCM control: same set up as # 2 w/ the relay plugged in. Bit tricky jamming it in place but it works fine.

These three each use power going through the stock fuse to supply the voltage to the fans so there is no need use inline fuses. #3 is effectively as good as the casper switch and the way to do it that Jazzman put up. #4 is the best solution so far and is pretty much what jazzman put up.

Due to the good amount of Electrical mods we did to my freinds car (strobes, fan override, ralley lights..ect) and is you have a lot of mods consider this:

#4) we ran a heavy gauge line (8ga) drirectly from his battery to inside the cabin (where all the relays and switches are) so all the mods can just draw power from that wire, one +12v terminal and there is a nearby ground they can all use, a common GND terminal. Avoids too many wires running around and straining existing lines that are already in the cabin.
From the +12v line connected an inline fuse that feeds a relay that will power the fans, pretty much the same setup as jazzman put up just I drew power from the battery, not the line going to the fans.

as for the wires I used 8 gauge wires for the ones that give power to the fans, I think 10 gauge may be enough for a GA depening on how much current the fans draw. (around 35amps on the Focus)

In my opinion if you know basic Electrical you can do this dirt cheap.
The only excuse for buying Casper's set up is if you really dont know electrical or anyone who does.

if anyone needs some help pm me, I'll be glad to help.

[Pvt_Murphy]

I've done a similar mod to my friend's Focus and will prolly do the same on my car.
Because I first did this when his temp sensor was borked there are a few versions:
here's a few of the configurations I did:

easiest to use crimp on spade connectors.

1) To just have them always on when the car is on, I pulled the relay, and ran a wire from the + 12v terminal of the realy socket (only gets power when key is 'on') to the terminal going to the fans. (quick fix w/ 6" of wire if you ever need a temporary solution)

I'm not sure if it is the same in a GA, so if that terminal gets power when the car is off to, take a multimeter and find a fuse terminal of suffiencient amperage (40+, maybe 30+) that only gets power when the car is 'on' and stick your wire in the terminal that goes out of the fuse and jam the fuse in there, that way the line you are using to power your fan has a fuse on it.

2) To have manual only control: run wire from +12v from relay terminal to switch mounted inside the car to the terminal going to the fans back to the relay socket.

3) To have manual or PCM control: same set up as # 2 w/ the relay plugged in. Bit tricky jamming it in place but it works fine.

These three each use power going through the stock fuse to supply the voltage to the fans so there is no need use inline fuses. #3 is effectively as good as the casper switch and the way to do it that Jazzman put up. #4 is the best solution is pretty much what jazzman put up.

Due to the good amount of Electrical mods we did to my freinds car (strobes, fan override, ralley lights..ect) and if you have a lot of mods consider this:

#4) we ran a heavy gauge line (8ga) drirectly from his battery to inside the cabin (where all the relays and switches we put in are) so all the mods can just draw power from that wire, one +12v terminal and there is a nearby ground they can all use, a common GND terminal. Avoids too many wires running around and straining existing lines that are already in the cabin.
From the +12v line connected an inline fuse that feeds a relay that will power the fans, pretty much the same setup as jazzman put up just I drew power from the battery, not the line going to the fans.

as for the wires I used 8 gauge wires for the ones that give power to the fans, I think 10 gauge may be enough for a GA depening on how much current the fans draw. (around 35amps on the Focus) Just look at what gauge wire is feeding the fans in the wiring harness and use that.

In my opinion if you know basic Electrical you can do this dirt cheap.
The only excuse for buying Casper's set up is if you really dont know electrical or anyone who does.

if anyone needs some help pm/im/email me, I'll be glad to help.

If I ever get around to doing it on my car I'll put up the how to.

[95-GT]

The only change I'd make to these instructions is to tap into an Ignition switched 12v wire (Pink 12ga in ignition harness) and not the B+ constant. If you have it tapped into the constant and forget to turn the fans off I hope you have jumper cables handy.


The big time advantage of having it on a constant is that when you in the staging lines, your motor is being cooled.

[magyver]

The big time advantage of having it on a constant is that when you in the staging lines, your motor is being cooled.

plus, unless your deaf, you should hear your fans running when you stop your car, plus it would be so easy to put a light on it... so you get blinded...

wow, this is so easy and so cheap to do its not even funny guys..

find fan relay, cut the signal wire, wire that goes to the fan put that in the middle of a 3way toggle, the other end of the wire run that to the bottom of the 3 way switch, then from the fuse box run a fused wire to the top of the switch... DONE! shouldnt take ya more than 15 min to wire it up, it will take longer to get through the firewall.. no extra relay needed, only a 3 way toggle and some chunks of 16ga wire... and an inline fuse

[boost21]

im goin to attempt this this weekend, magyver can you elaborate youre setup with a pic or something, if not ill try the way with the relay...thanks...also this seems too good to be true cost wise...one question tho is the stock setup still active like the caspers switch?

[magyver]

try this

[sc02grandam]

try this

which bcm wire are you using? i think you meant to use the pcm?

[magyver]

the one that is feeding the relay... dont know what it is, all ya gotta do is find the relay itself and it should be easy

[boost21]

no need 2 do this 4 me nemore cuz with my WAI and SD hood setup i rarly see temps over 205 degrees....great idea tho and props to who ever dose this DIY mod

[tejohnson]

The way I did it was by grounding the pins off the PCM, the way the PCM operates. If you go about this, you will need to delete two DTC's for faulty fan relays using Powertuner...

Here are some pics:

http://groomlakelabs.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=2327&g2_serialNumber=5

http://groomlakelabs.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=2330&g2_serialNumber=5

http://groomlakelabs.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=2333&g2_serialNumber=5

[badboy2451]

hmm...it sounded a lot more easy before you chimed in todd lol

[tejohnson]

It may not set an SES, but codes P1651 & P1652 were set. As you can see by the schematic above, I have 2 switches for high and low fans that can be turned on, even when the car is off (the third switch is for performance shift mode). The way I went about it may be totally different than what is suggested, or the DTC's don't illuminate the SES light.

[j_yewchin]

i hate wiring diagrams, ;crap hahahah. so thats where our pcm is...
so todd, this will set codes, but not the light you say?
thats fine with me... i dont have access to a powertuner to delete the codes, but if there isn't a light on, its all good.
i definately like the way you did it... thats a very nice setup with those 3 switches...
so if i wanted to activate the high speed fan only, all i'd need is one switch and some wire?

also, off topic, but performance shift mode eh? thats intruiging... how much of a difference does it make? slightly firmer shifts are actually not bad for the transmission right? or is it the other way around? i know to make a smooth shift the tranny purposely slips slightly, doesn't it...?
yeah i dunno, but i'm sure this thread will come in handy

[tejohnson]

For P/S mode, you will need Powrtuner to modify the PCM, then the switch to ground pin #21.

If you look at the schematic, you will see I included relays on those switches, mainly since the switch has a backlight, and the load is +12 vdc. So the switch activates the relay, and ground the PCM pins. You could do one switch, and ground both fan relays to activate high speed mode. I just wanted low & high.

[iceman]

I remember doing this way back when, and IIRC it did turn on my SES... was quite a while ago and I was doing other things at the same time so who knows.

[j_yewchin]

hmm... hopefully i wont use it enough to turn on the ses. thanks iceman

where do i go from here? :D is the area i marked with the arrow the right area to start tapping wires?
lol this is as far as i've gotten. i can get the pcm out, but not until i know what im doin...

[Sprucegagt]

The DTC's are (obviously) being caused from the PCM noticing when the fan relay pins are being grounded when they shouldn't be. There is a simple way to correct this. Run each fan relay lead from the PCM to the normally closed side of each respective relay. That way you will still have normal fan operation yet still have override control whenever you want.

[iceman]

Yeeeup... this is basically what the casper's harness does. NC pin of each relay is 87A, j_yewchin... or you can diode isolate it. either way

[tejohnson]

You do this way, but you just get the DTC. I opted for this due to accessability, and working with grounds, not hot lines and worries with fuses... Plus, it is cake to delete the DTC's with Powrtuner.

The wires are on pins 6 & 7 of the C1 (blue) connector (on the left side). Quite a few different ways to approach it....

[Sprucegagt]

Agreed. I was putting that out there. I knew you wouldn't need it Todd. ;)

[j_yewchin]

many ways to approach?
i want the easiest way to approach it. hahahah... sorry guys, lots of great information, i just dont know how to apply it. kind of embarrasing. i'm rather new to the whole electrical mods idea...
basically all i have is a simple switch, and i'll need to find some spare wire.
do i need to buy a relay? i can go to circuit city... if i know what i'm doing/going for.

and todd, do you mean the blue connector on the picture i posted? or yours? if mine, then that looks pretty easy.

:banghead i'll get this done eventually

[tejohnson]

many ways to approach?
i want the easiest way to approach it. hahahah... sorry guys, lots of great information, i just dont know how to apply it. kind of embarrasing. i'm rather new to the whole electrical mods idea...
basically all i have is a simple switch, and i'll need to find some spare wire.
do i need to buy a relay? i can go to circuit city... if i know what i'm doing/going for.

and todd, do you mean the blue connector on the picture i posted? or yours? if mine, then that looks pretty easy.

:banghead i'll get this done eventually


I would approach it on the other side of the fan relay as suggested above. I have no real diagram to demonstrate, but it would be your best choice since you have no way to edit the PCM.

[j_yewchin]

ok so whats the minumum amount of items to be on ones shopping list to do this?
i've got a switch so far, thats it.
and can anyone edit my picture that i posted and show me the next step..?
i'm too new to this.... :duh:

[cmtapanes]

Hi tejohnson, when I got my PCM on the instructions I received with my new pcm they say how to get my performance shift mode by connectin pin #21. Do you see any kind of improvements? When do you use the performance shift mode?

It may not set an SES, but codes P1651 & P1652 were set. As you can see by the schematic above, I have 2 switches for high and low fans that can be turned on, even when the car is off (the third switch is for performance shift mode). The way I went about it may be totally different than what is suggested, or the DTC's don't illuminate the SES light.

[tejohnson]

Hi tejohnson, when I got my PCM on the instructions I received with my new pcm they say how to get my performance shift mode by connectin pin #21. Do you see any kind of improvements? When do you use the performance shift mode?


Well, not to pollute this fan switch howto, but I see no difference. Why you ask? Because my perfromance mode tables are currently identicle to the reqular values. Meaning more of a permanent performance mode at the moment. This will be channging soon...

[j_yewchin]

oh yeah forgot to post back. i did find a easy way to do this for anyone interested.
it WILL turn on a check engine light if you use it for more than a minute or two.
however the ses light will turn off after a day or two.
i usually use it to cool down the car at the gas station or after a lot of idling.
i experimented with 2 modes... 2 fans low speed and 1 fan high speed.
i ran a switch to the inside of the car with high speed mode.
on my picture i marked x's on the relays. (my finished result looks a LITTLE better than the picture shows, lol)
check before you do this with a multimeter. the one your grounding should be around 0v. if its 12v, gounding it is a bad idea :D just make sure your fuse box is wired the same was mine is... you'll notice most of those say made in canada on them. so perhaps something is different than the american model.
you have to ground that pin/prong? whatever it is, of the relay. which turns on the fan.
if the bottom one is grounded, thats low speed mode.
if the top AND bottom are grounded, thats high speed mode (same as having a/c on, but you can use this when the car is off)

i only needed about 8 feet of wire, and a 2 position switch that i had sitting around anyways.

GOOD LUCK