Honda / Acura K20a K24a Engine Forum banner

Eliminate Fan switch.

16K views 19 replies 13 participants last post by  Alswizzo  
#1 ·
For those of you who want to save a few bux. you dont need to put in a Fan switch. Could be this was added to jack up the price on the harnesses. whatever... This is assuming u have kpro. just hook up c101 slot 7 directly to directly to the fan relay Negative side. I seen so many people on here assuming that these wires are automatically Positive power wires.

If your in doubt check for yourself but beware, even the infamous hondata wiring diagram is wrong, and that thing is passed around like crazy. it says the c101 slot 7 is from b8, Hondata really needs to fix this. makes me kind of wary on some of their electronics.

Also the guy mat there is a real dick. he talks like we need to fight in order to understand each other and then suddenly appear on this clear line of communication.

You dont need a fan switch if your programmable ecu tells the fan when to turn on and off.
 
#2 ·
chieF rocka said:
Also the guy mat there is a real dick.

you are the tenth person to say that.... but at the end of the day, I can understand the hostility. I bet hondata gets a million phone calls from people on less reputable forums asking if they (hondata) can make their fater's dx into a type s and the like.... if only there were some way to screen retards and telemarketers over the phone, the world would be a better place, but alas, anti-gun laws in the US are such that many people are assholes over the phone when they are unsure who is on the other line. I am very guilty of this. And as much as I wish to agree with you regarding that particular hondata employee, it makes perfect sense to me. What doesn;t make sense, is why on earth doug and derek are so nice over the phone :confused:
 
#3 ·
So that totally eliminates the need for the temp sensor and fan switch on the rad. hose for us swapped cars? At least those of us using K-Pro.
 
#6 ·
Yea, i'll see if i can get some pics. Ur probably going to need the b series temp sensor, unless u can find out if your cluster can work off of the exsisting head ect. but i would use 2 temp sensors anyways to be safe.


Its just the Thermo fan switch thats not needed. the one that goes into the RSX radiator. Think of a light bulb and a battery, u need positive and negative for the light to turn on same thing with the fan. The relay is added so you dont have to have a full 14 volts to turn on the light bulb or fan. you can wire up the heavy electrics to the relay and use small electrics to turn the relay (switch) on. When the relay clicks it connects the positive and negative terminals turning the fan or bulb on. The Relay is another Light bulb itself, except instead of having alot of power to create Light or Rotation ur just connecting a circuit so you can have very minimal power to the relay. The relay is wired so the positive has a constant LIVE wire. that way when the ecu wants to power something it just connects the negitive to an exisiting ground, so not that much flows through the ecu. This is on the B connector at slot number 6. If you notice on the k20 engine harness the theres no relay wires on the motor so this wire has to go through the c101 plug, which is slot number 7. then slot number seven is supposeed to run into your cars loom and to the negative fan relay terminal. Base harnesses dont work at least the one i have dosnt.

i noticed on my crx that when the fan relay switched another relay switched, i think this was the ac condensor relay, as it was connected somewhere on the engine loom to the same negative wire. so i just pulled an tossed this relay. i left the thermo fan switch disconnected. (i never bought one). at first i was thinking this needed a jumper wire to complete the loom so the ecu will work. but on my harness this wasnt the case.

the thermo fan switch is also a negative connector. it has a negative ground wire on the back of it and a dead wire. when the fan switch triggers it connects the two wires and completes the circuit. Some people think one pos one neg on the back of this. Nope! it just completes the negative loom, turning the relay on. i figured if the kpro has option for custom fan setting what the hell is this switch for? Plus i didnt want a dum inline hose adapter lol. anyways the ecu triggered the FANC when temp hit desired temp anyways.
 
#8 ·
matt is a jack ass. Next time I will sucker punch his ass. After that I will steal his car. then sell it on ebay.
 
#9 ·
well on my dc2 its controlled by the ecu or whatever triggers it.

just used the stock plug with the hasport thing. didn't have to do anything with the wiring. you either need that shit or rsx radiator. how about the temp indicator?? do u have that wired.
 
#10 ·
The point of having the fan triggered by a temp sensor in the radiator is to turn the fan on as soon as the coolant that has just passed through the radiator did not get cool enouigh. Without this, you have to wait until the too hot coolant gets to the sensor on the engine, and there will be a whole hose of hot coolant behind it. Certainly not the end of the world, just not as good as the stock setup.
 
#12 ·
I'm going to update this thread with some useful information:

ECU Position B6 will Ground-out when it reaches the temperature specified in the Engine Protection screen on Hondata's K-Pro software.

It does not carry enough amperage to turn on a fan. A Relay must be used.

These are the Relay positions:
30 - Ground (activates fan when switch moves to 87)
85 - B6 (when temp reaches "force fan on" setting, this wire is -12v ground)
86 - 12v+ (this provides 12v+ to the coil - is grounded by 85)
87 - Fan Ground Wire
87a - nothing

Wiring Diagram
Image


Off
Image


On
Image


To understand how a relay works, see this link:
http://www.the12volt.com/relays/relays.asp


Rywire.com =)