jeffrored92

Guys,

Been reading the fan mod stuff quite extensively. Got a copy of the wiring diagram and it all looks pretty self explanatory. Grounding out particular wires will energize the relays and turn on the fan motors.

My one question is this - grounding the necessary wires on relays 2 & 4 (both green/black according to the wiring diagram) will be grounding the ECU pin that partially controls the fan operation. Can someone please reassure me that this will not fry my ECU (ie: tell me you've done it and it didn't cause any problems)

I don't think it would but just seeking reassurance before I go and get my fan mod happening. I'm liking the idea of the rotary switch someone posted recently - it sounds good and I might have to rip it off

adam c

iTrader: (2)

For this fan mod, you don't want to ground the wire without a switch. It will drain, and kill your battery.

http://www.scuderiaciriani.com/rx7/fan_mod.html

Kento

You are not grounding the "ECU pin"; you are basically activating the thermoswitch that is one of the components responsible for fan operation (however, activating the thermoswitch also tells the ECU that the coolant temps are high). As long as you check out the wires carefully and ground the correct ones, you won't have any problems. (NOTE: if your FD has had the fan wiring update done, the wire coloring may not match the descriptions given for the fan mod, and you may not be able to run your fans on medium or high unless you ground the relays in the correct sequence. Be sure to use a voltmeter to check).

Section8

iTrader: (6)

I did this mod as soon as i got my car, using a small toggle switch in the center console, and I've had no problems at all since May using it. I also noticed after I did this that my car started running the fans for 10 minutes on its own after I shut it off. Nice side effect.

Kento

That is the "10-minute shutdown sequence" portion of the fan wiring update. Once the temps reach a certain level (triggered by the thermoswitch--which the fan mod activates--which tells the ECU that coolant temps are high), the ECU automatically goes into that mode after engine shutdown.

KevinK2

doing the "voodoo" mod at the relays, vs the usual switched test wire near the ecu, will gnd an ecu pin that normally supplies the ground based on thermosensor resistance. I also tilted my head on this one, but apparently it works ok. I think there is a test ground for this pin in the test plug, under the hood ... TAB ?, which would be reassuring.

leaving the car parked with the relays grounded for a week or two, can kill a battery, even with fans not running.

jeffrored92

I'm starting to wonder how many of you guys consulted the wiring diagrams or just jumped in and started playing with the wires!

KevinK - I think your right, the wire to the ECU pin is physically connected to the diagnosis connector elsewhere in the enginebay. My guess is that for diagnosis you ground the tab, which forces the ECU pin to ground, and activates relays 2 & 4. If this is the case then it should be safe, I guess.

It's just I was reading the wiring diagram and couldn't figure out exactly what that ECU pin was doing. There was some section that specified the voltage on that ECU pin when the fans were running to be Vx (x coz I cant read the small symbol) and the voltage when the fans were off to be <1V. That seemed backwards. Then there was a section beneath it that used the terms "OFF" and "ON" rather than voltages, and that described the pin as being "OFF" when the fans are running, and "ON" when their not. That seemed more like what I expected.

For everyone else, what I want to do (with maybe a rotary switch) is to have the ability to manually override the fan system to any fan speed I desire. Switch will do this by grounding the wires as necessary. Or if I leave the switch in the off position, then all wires I patched into will be floating and hence the fan system will run as per normal. I will also do the miata thermoswitch mod. Most times I will be just running off the miata thermoswitch but I also want to ability to manually override the fan system to a desired speed.

Kento

If you don't have the wiring update done, then the voodoobox/Disney mod does ground the ECU pin (sorry, my bad). If you do have the update, however, the wiring is switched around (mine had different coloring as well as sizing; several others reported this same thing), and the Disney mod as pictured won't work. You'll only be able to trigger low speed on the fans by grounding one of the leads (on mine it was black/green) to relay 3 via a pole switch, which is basically activating the water thermoswitch on the wiring diagram (yes, I checked, because I couldn't figure out why my wiring was different and the mod wouldn't work). Any other relay trigger combinations will only result in the 10-minute sequence starting after shutdown. This is all a moot point if your wiring is the same as described in the voodoobox/Disney mod.