kung stew

So I go to do the voodoobox fan mod, and find out I have 12.8 volts on the wires to be spliced into/grounded. Based on the excessive wiring around the fan relays, my car has had the fan control "update" performed. I found a thread that seems to bypass the whole relay issue for fan control here:
https://www.rx7club.com/forum/showth...ND+which+wires

Will doing this version screw anything up in a car that has the "updated" wiring?

thanks,
Stew

Kento

I think if you've had the wiring update done, grounding the extra ECU wire won't do squat.

PM FDjunkie, he should have the wire coding and wiring sequence to get proper fan setup and speed. You're going to need a double pole switch in order to get medium speed.

kung stew

Thanks, Kento. Any idea if putting power on the blue wire leading to the fan will work, as described in the thread above? I'll pm FDjunkie as you suggested. Anyone else have a solution...I'm sure plenty of people have had to get around this problem!

Stew

kung stew

^^

kung stew

Bump...

C'mon, o sage rotary experts. I KNOW this has been done. I really don't want to fry something in the electrical system by just randomly trying to figure out which wires do what. I've looked at the wiring diagrams, but I can't find any for this "updated" wiring.
PLEASE HELP...car wants fan control...must fulfill car's desires.

Stew

Kento

Grounding the blue wire won't work, because the whole idea is to fool the ECU into thinking the coolant temp is hotter than it is.

If you want immediate results and only have a single pole switch, just tap into the black/green wire from either relay #2 or #4 (I believe with the wiring update, the two are already tied together, so it won't matter which). This will give you low speed. Remember that this mod runs the fans with the ignition switch on or off, so don't forget to turn it off.

For medium speed, you'll need a double pole switch, because the other relays must be energized in order for the mod to work when you ground relay #3. I'm pretty sure the wiring codes from the voodoobox site are correct here. You need to remember that this will also trigger the 10-minute shutdown sequence if you run this mod anything over 2 minutes before shutdown; but you must remember to turn it off here as well, otherwise the fans will continue running past 10 minutes and drain your battery if you're not careful.

I'm wondering if triggering medium speed on either setup (non or updated models) will affect timing and fuel curves (effectively "dialing them back"), since you're triggering the temp sensor that tells the ECU coolant temps are high.

kung stew

Hmmm...not sure about the effect on the fuel curves. However, my problem is that I have voltage on that Green/Black wire (from both relays). Electrical systems aren't my strong suit, so what would grounding a wire w/ power on it do? I would just give it a shot, but I don't want to pop a relay, etc.

Thanks,
Stew

P.S.-
Kento-"Grounding the blue wire won't work, because the whole idea is to fool the ECU into thinking the coolant temp is hotter than it is."

I think the idea was to put switched power onto this wire leading into the fan. FWIW

Kento

Whoops, yeah, you're partially right. For low speed it is, but if you look at the wiring diagrams, grounding the wire on the number 3 relay activates the water thermoswitch, which is what switches the relays to send additional power to the fan motors. It's this point which makes me wonder if running medium speed will trigger the ECU to dial back fuel/ignition curves, since it thinks the coolant temps are dangerously high.

Voltage to the black/green wire is OK, since what you're doing is completing a circuit to activate the relay. Just do a quick test; quickly ground the black/green wire, and see if the fans come on low speed.