I'm assuming you used a good temp gauge when you set it? Those probes are a terrible indication of how hot your coolant actually is.

 

I use a laser thermo thing to set the temp switch. I didnt go by the water temp guage.

ANd i bought mine at auto zone=) for about 30$ +- came with relay and fuse. adjustable.

The hard part was getting the switch set at the right temp. The switch was easy to adjust in the lower temps. Until you get to about 170. Then no matter how little you move the adjuster it would jump to from 170 to 190. then i got lucky at 184 or so=D left it there.

 

I'm using one too. It works like a champ once you get it set correctly. My probe is pushed into the fins just under the radiator inlet and the controller is mounted just behind the passengers side headlight.

The only splice I made was to switch the relay with 12V ignition power and I think I pulled that from the AAS harness connector that I am no longer using.... so it wasn't really a splice at all.

 

That diagram is about as simple and straight forward as it gets. I mean no offense, but if you can't make heads or tails of that schematic, you probably shouldn't be attempting it in the first place. Try to find someone who has done some car stereo/alarm installs who knows the basics of a bosch relay. They look confusing, but are actually very simple once you grasp the concept.

Pole 85 and 86 really just turn the relay on or off - thats it. The relay typically rests on 30/87a and when you energize the coil (poles 85/86), the relay just switches to 30/87. Pole 30 is just your feed - it an be 12+ or ground - or whatever.......

arghx - GREAT post. Thanks. Its always good to visualize the schematic before digging in. And to the others - yes, you can wire it many different ways, but this appears to be the best in my opinion. Please don't criticize the mans post or way of wiring it if it is different from yours.

Again - AWESOME post and great schematic!

 

great post! I hate heat. Do you have the pics of this set up?

 

just caught this post, thanks for clarifying.

 

Thats beautiful thank you!
Just wired it up but waiting on the new fan..

 

Just wanted to add something relevant and useful to the thread. Here's my schematic for wiring a 2-speed Taurus fan the proper way on a S4 using the OEM thermoswitch. The red relay has to be a high current one since it operates the high speed mode. The only thing I couldn't figure out was to only use the idle-up function when the hi-speed mode was active, so I left it always on.

 

for those of you who may be running a factory thermoswitch now, do you have any feedback now that the weather has been warming up?

 

THANK YOU
This is by far the best and most useful write up i have read in the 5 years on this site. Mine run on a switch with a relay and im going to swap it over asap. Even my stupid haltech can seem to get it right. nice work man

ARCHIVE

 

One thing I want to point out:

In the diagrams I label the idle up as requiring a BAC valve. But even without a BAC valve supplying extra air past the throttle plates, when the ECU receives the idle up signal it will still advance the ignition timing about 15 degrees--or at least, that's what the training manual says. I haven't verified it with a timing light, but I don't see why that wouldn't be true. The additional timing advance should help keep idle speed stable. So it really couldn't hurt to hook up the "idle up" function on cars which have had the BAC valve removed.

 

While this is a great write up and install diagram, I think this has pretty far beyond a simplistic thermo-trigger setup.

As long as you set, say your high setting to the thermostat (new, replaced), and the low to always on (or low to thermo and High to a manual toggle), there shouldn't be any issue.

 

These diagrams are about as simple (safely) as it gets. Are you not using a relay or fuses in your setup?

 

Quick question:

Why would you wire it up so that the fan can stay on after the car shuts off? It seems to me that since the water pump stops when the engine stops, all that would do is cool down the radiator and not the engine itself.

 

If I was gonna do it this way what could I tie the 12v ign wires to??

 

The +12V ignition power for the relay can come from the green diagnostic connector if you are s4. As for the fan power itself... I'm really reluctant to recommend a particular factory ignition-switched circuit for that. Electric fans pull a lot of current. I'm concerned there would be problems if you didn't use a relay and pull it right from the battery.

 

No, no, ya loon. I meant that it was always on while the engine was running, regardless of thermo trigger....


Sheesh.

 

Sorry, that was meant to be in reference to these earlier posts:

 

OH. My bad.

 

i have an s4 and to simplify things im setting it up with an s5 thermo-switch since its the same threading. Does the original engine harness plug for the thermoswitch lead back to 1O??? that way i can set up the idle up function easier?

 

S4 engine/"emissions" harness, turbo or non turbo, is pin 1E on an s4 ECU for idle up. S5 engine/"emissions" harness is pin 1O for the S5 ECU idle up. So if you are using an s5 thermoswitch in an s4 car with an s4 harness/ECU you still need pin 1E to trigger idle up.

 

sorry, read the wrong pin number. Does the original engine harness plug for the thermoswitch lead back to 1E???

 

Pin 1E is an input to the s4 ECU to tell it that the A/C has been engaged. The idle system is designed so that when the A/C is engaged the idle speed is increased and the ignition timing is advanced. When you run a wire to pin 1E (1O if you have an s5 ECU) you're "tricking" the ECU into thinking the A/C is on, even if you don't have A/C in the car. The A/C idle up helps maintain battery voltage from the additional electrical load of the electric fan.

 

thanks for the info. so im guessing from this info its not the wire leading to 1E

 

the s4 and s5 thermo sensors are the same thread pitch of m16x1.5 right? if so advance auto parts has failed me!!

i'm concerned this is the stock s4 one, let me know if its not - http://www.napaonline.com/Search/Det...6SB_0213378799