redbird8628

iTrader: (1)

i wanted to know before i go on the 3.4 cyl. head plug adventure, will this adjustable fan switch work? the probe inserts in between the rad. fins I figured, this seems cheaper than a hypertech fan switch, its adjustable from 180-240 degrees, and it will take as long to wire as it would to remove the cylinder head plug on the 3.4 im getting this this thursday. has anybody used this product before? Its Summit part# FLX-31147

Thunderfest

Yes it will. It is designed for just that.

The problem with that type of adjustable thermostat is it is set for one on/off temp and there is no dwell time. What I mean by this is if you set it for 172*, it will come on at 172 and go off at 171*. You want a relay that has dwell that will turn the fan off at least about 10* lower than the turn on point so that it does not just keep cycling on and off- even after you shut the car off.

redbird8628

iTrader: (1)

im not sure how i would wire a realy like that or where to find one for that matter

daves12secV6

iTrader: (3)

why not just run a manual fans switch
its easy as hell to do and gives u full control over the fan
my temp sensor that controlled the fan went bad my fan wouldnt turn on the fan till 250 degrees. alls u need is a togle or rocker switch 1 ring terminal, and 1 female blade terminal, and 1splice conector and about 4-6 ft of wire depending how u run the wire to the relay

Gumby

don't buy that switch. I'll sell you mine for half price if you really want one. They are unreliable. Sometimes they stick on for hrs killing your battery and sometimes they don't come on at all. Garbage.

Buy a set range one, the adjustable ones suck.
Manual switches are fine if you can remember all the time.
I would forget as it didn't need it all the time and its sucked juice the AMPs could be using.

With enough cold air mods you don't even need a fan unless you sit still for 3-4 mins. But the main part is removing the AC rad. My fan is used maybe 1hr or 2 a year. Only when I goto the bank do I sit long enough where I need to kick it on.

daves12secV6

iTrader: (3)

thats liek me if im doing over 10 mph i dont need my fan, if im stuck in traffic for more then 10 mins at a stand still i kick the fan on for a few mins, if im on the highway my car wont go over 160

xplane

on the manual switch all you have to do is use the ignition supply like ya do for a radio to supply power to the input on the switch and then from the switch to the relay. that will prevent you from forgetting and running the battery down on accident. also i put a temp gauge in the car and put the sensor where the idiot light switch was but now if i plug in the AC fan switch it wont turn on at all did that also control the fan turn on? i thought that the 2.8l had the computer control it exclusively.

daves12secV6

iTrader: (3)

that pretty much what i did i ran a wire up from the fuse box to my switch then from there to the fan relay, the trick is though the turn on wire to the relay is always hot,( uses the ground wire to control fan on and off)so what u have to do is find the wire that grounds the realy, weather its controled by the sensor or computer im not sure, but u cut that wire and put the ground to a body ground so its always grounded, then u take the wire u ran from the switch to the turn on lead of the relay.

dcm01003

could someone draw a schematic for that "simple" wiring of the manual fan switch. I had one in my car, but dealership removed it when they removed aftermarket alarm system. They said it was wired to the alarm system, so they had to cut it, i think they did it on accident and didnt want to fess up to it. Anyhow, would appreciate some type of detailed diagram

Thanks,

Dave

Gumby

And just so you or anyone else seeing this knows.

That temp probe for the adjustable one your posted, that I got.

It goes inside the radiator top hose.

Sounds strange but it still works and seals some how. you just bend the probe wire back over the rad inlet, stick that piece of rubber between it and rad inlet. Then just jam the rad hose back over and some how it still seals up and works fine with that wire fishin through like that.

daves12secV6

iTrader: (3)

dcm i can do one better then a schmatic, i can get ya pics to, u just have to wait till tom since i dont have my digital camera

dcm01003

sweet!

daves12secV6

iTrader: (3)

dcm i forgot the camera while i was home and i wont be home tonight till prolly 3 am.So ill get the pics for u first thing tommorow morning.(well as long a si dont get stuck in the snow storm were supposed to get tonght.(whish i had something other then 3rdgens to drive in the snow)lol

The_Raven

I would rather replace the switch in the head (swap out the plug).

Now I have one question, as I'm not 100% familiar with the 2.8 F-body wiring/sensors.

Does the ECM control the fan? I figure it would.

Now, on other 660s that I deal with the sensor in the head is for the gauge, while the one in the intake is for the ECM.

What I'm thinking here is this:

If the I am correct, in that the ECM controls the fan, and the head mounted sensor is actually for the gauge, and not just a simple temp switch, you can simply use a 3 wire CTS. The same one that comes with the 3.4, swap it into the 2.8L intake and change a connector, so that now the Gauge and ECM pick up the readings from the same point.
This is what is done for the 3100/3400 swaps into the 2nd gen Cavaliers and also what I will be using in my Jimmy.
Also GM would use or most commonly use a temp switch in the intake for fan control, not the head, if there was just a switch.

Also, not a way I recommend, due to impedance changes, but I have known a few people to tap the gauge wire into the yellow CTS wire for the ECM, and had good results.

One last question, 1986 was the first year of EFI in the F-body, correct?

daves12secV6

iTrader: (3)

im not possitive but i belive on sensor is for gauge/ecm ,and the other controlls the fan directly,

Toehead

I have a 1985 Berli with 2.8MPFI
Also, I have examined the ROM for my car with tunerpro and the ECM does indeed hae a value for fan on

daves12secV6

iTrader: (3)

pictures of wiring in manual switch

first here is the fan relay

here is a shot of the botom of the relay conector

and another

and the switch

daves12secV6

iTrader: (3)

the green a white wire needs to be cut and grounded to the car chassi, the tan and white wire gets cut and spliced into a switch of ur choice i.e rocker/toggle, and then the switch gets wired into ur fuse box on an accessory circut, if ya need anything more detailed let me know

xplane

Radio shack makes some really cool rocker switches that are black and would fit right into the car interior like they were supposed to be there. heres the one im gonna use http://www.radioshack.com/product/in...entPage=family

xplane

heres one photoshoped onto daves98RS's console pic not to shure about scale but it gives you an idea.

The_Raven

Why are you guys cutting that trigger wire to the relay?

It would be better to just tap into that wire, so that the fan will still turn on at the predetermined temps, incase you forget to turn it on.

This "mod" has been done by the J-body crowd for years now, probably before I got into that scene back in the mid '90s, and not once has anyone cut the wire and disabled the factory fuction.

xplane

I was gonna ask if that was possible i just didnt want to risk it Frying the ECM on me. so you just saying T off from the ECM ground to the switch? thats kinda what i was thinking

dcm01003

ok i see how it should be connected to the turn on lead, but...if i didnt want to disconnect the factory function how would I wire it up underneath the dash and to the relay.

dcm01003

ok nm...im just an idiot and didnt see the post beneath the pics, however, will cutting the green wire and grounding it to the car chassis disable the factory function?

Also, is that a performance or factory replacement rats nest you have installed near your fan relay. Looks hot!

Dave

The_Raven

Yes, cutting the wire will disable the factory functionability.

Just T into the green/white trigger wire to add the ability to turn it on/off at lower temps.

dcm01003

Ok i pretty much have everything in order, just one more thing.
I know you connect to an Acc circ in the fuse panel from the switch, as well as the turn on(tan/white) lead on the fan relay, but what wire am i splicing into the ground wire of the fan relay?
Is it the ground wire on a 3-prong switch?

xplane

no i think he is saying that all you have to do is T off of the ground wire, Run it to any two pole switch that will just break the connection and the other pole to a ground and that will alow you to manually turn the fan on cause the only thing that the ECU does is create a ground to turn on the fan relay on or off. This should also work with a fan switch in the head of the engine to right? so i should have it abe to be turned on by the ECU, Temp switch, or the manual switch cause all i have to do is provide a ground from any of those points.

The_Raven

Your first part was correct, all you need to do is provide a ground signal to the green/white wire.

You can NOT use one of those illuminated switches, to do this, well you can, but requires another replay to invert the positive signal to a ground again.

The second part of this post is incorrect, the yellow wire to the ECM is not a simple switch on and off, it is variable resitance based on tempurature, so that the ECM knows what temp teh engine is running at.

xplane

i know that the yellow wire goes to the ECU im not talking about that im talking about substituting a Temp switch installed in the pass side head for a manual switch. i am kinda wanting to run all 3 ECU control, temp switch, and the manual switch.

dcm01003

so I dont need to T off the tan/white wire and connect it to an accessory circuit? Now I am just a little confused, because there was a fan switch in my car until a dealership removed it and I have no idea how it was hooked up, other than it was connected to the acc slot on the fuse panel. However, when it was connected,the factory function still worked when the switch was off.

So am i just t-ing off the green/white wire to a switch and then putting another wire to a ground source and that should allow me to turn the fan on and off? That doesnt sound like enough if the tan/white wire is the "turn on" lead.

Ok, please forgive my stupidity, but i have been drugged up for the past two weeks because of back surgery and just want to get this right. The_Raven, could you please explain in detail what I would need to do to create a fan switch that would allow for factory operation.

Dave

redbird8628

iTrader: (1)

thanks for all the help, but i just drilled a 9/16" hole in the intake manifold and ran a 3/8" pipe thread tap, worked out real nice and clean

The_Raven

Uggg....

That's not a switch, it's also variable and if memory serves is for the gauge cluster, unless the gauge cluster onl has a light instead of a gauge, then all you'll be doing is turning the light on with the switch.

The Fan is controlled by the ECM, that takes it's reading from the ECT in the intake, which then takes the varied resistance and once a threshold is passed sends a signal to the fan relay to turn it on.

The_Raven

The Tan/white (sometimes refered to as brown/white) is not the turn on lead, this will be ignition switched.

THE GREEN/WHITE WIRE IS THE GROUND TRIGGER TO TURN THE FAN ON AT THE RELAY!!!!

IT'S THAT SIMPLE!, Ground that wire through a switch and you will have both factory operation and be able to turn it on/off at a lower temp.

xplane

I just did it 5 mins ago think of it as just taking a wire from the green one to the chassis to make a ground. Fan would run nonstop as long as the wire is grounded right? well ya just put a switch in the line to control when it gets ground. thats all you need to do.
Edit: i was not talking about the Light switch or the CTS i was talking about getting an aftermarket Fan Switch from oreillys or some where else and doing with it the same thing i did with the manual switch.

The_Raven

There you go.

The_Raven

This is for 2nd gen J-bodies, but it's essentially the same, at least as far as wiring goes, component location will be a bit different.

http://www.v6z24.com/howto/fan

dcm01003

ok cool, was just confused by the above pictures and such and having to splice etc...

Thanks

xplane

well im thankfull for your help on how to wire this but i still cant figure out why it wont come on even at 240* on its own.

The_Raven

Sensor in the intake possibly bad? Wiring between it and the ECM broken, relay not working? Wire between ECM and relay broken?
Many reasons.

xplane

none of the above. New ECU, have checked the wiring from the CTS to ECU, checked the CTS it works. Does any one know what Voltages translate to what temps? what should it read maxed out, what should the temp be equal to at 0 volts? If i know that i could check and see if its not reading to cool or something. Fan relay is good so is all the wiring assosiated with it cause the ECU will turn it on if i unplug the AC pressure switch but it will run non stop.

The_Raven

Next question, what are you suing to get this temp of 240*?

xplane

IM not im TRYING to get the fan to come on like its supposed to BEFORE it gets to that. that is the highest i have let the car go to before i let it cool off to see if the fan would work on its own. This fan is about shot you can hear the thing rattleing and scraping on its worn out bearings and before i have to get a new one i would like to figure out how to get the fan to come on only when its needed without having to flip a switch. I am not the only person who drives my car. i would like it to come on at say 220* or mabe even a bit lower but stock turn on temp would be ok with me if it keeps my car from over heating.

The_Raven

uhg...

What are you using to determine that teh engine was at 240*, before you shut it down?

RSFreak

My '91 RS had that very unit on it when I got it. I t worked very well and I never had a cooling problem with that car. I wish I had kept that switch when I parted the car.

xplane

the gauge i installed. it might be off but i really dont think it is off by 20* i have a 192* Tstat and sitting at idle with the fan on it sits right on 190* mark and crusing down the road it reads about 185*.

The_Raven

Ok, and by the rest of your descriptions sounds to be pretty close.

Without actually checking those things myself, it's hard to say.

xplane

so if i bought a aftermarket Fan switch and installed it in the pass side head in the port where there is just a plug and wired it to create a ground like my manual switch does that should work correct? get like a 200* fan switch.

CamarosRUS

TTT for a question. I bought a adj fan switch and need to run a switched wire. Is there one located anywhere in the engine bay?