gpracing

Alright, so I think I've read all of the different threads and how-to's on performing a "fan switch mod". However, none of them create the solution that I am looking for. I have a race-only CYM and I want the fans to be hard wired to a switch on the console. I want them to run on high as soon as I turn the switch on, and keep running on high until I turn the switch off or disconnect the battery cutoff switch. Has anyone performed this mod? Is it possible? I have the workshop manual, and after going over the wiring diagrams I'm not quite sure where I would wire it in wiithout upsetting the ECU.

Mahjik

iTrader: (1)

Just wire the fans to a switch and to power. Bypass the relays and anything else.

DaleClark

iTrader: (55)

Actually, just wire a switch to ground and to whatever relays you want to trip. The relays get a ground signal to switch on. Might want more than one switch so you can pick what relays you want on - if you're running the fans at high, you may actually over-cool the car, which hurts performance.

Dale

Gadd

go to page z-42 Diagram b2. At the fan relay connectors b2-01, b2-02 and b2-04 ground the wires V on relay one, G/B on relay two, and L/G on relay Three. Now your fans Are on high any time the ignition switch is on. If you want them to run with the ignition off, you need to suppy 12V to any of the B/Y wires at any of the relay connectors.

mad_7tist

no actually if you ground the relays ( i forget the color) they will run with the car off also. hell if its a race car run a fused wire to the positive wires on the fans and run a switch in the ground side in the car (like mahjik said). make sure the wiring is correct or the fans may turn the wrong way

Gadd

If you bypass the relays make sure you run wires of the proper size and a switch that can handle the amps that the fan motors draw.

Gadd

Upon further contemplation. if you suppy power to the 12v to the B/Y wire you'll be powering a bunch of other things on that circuit. You'll need to isolate the B/Y from the wiring harness.

Kento

If the car has had the fan wiring update installed, the wiring diagrams in both the FSM and the various fan mod sites will not work if you want to set up the fan mod using the stock fan relays. In your case (a race-only car), you will probably be better off just hard-wiring the fans with your own relay setup to run the fans on high (using the FSM to see how to hot-wire the fan motors to run at that speed). The fans pull a lot of amps, and the relay will help you avoid welding your switch shut after repeated use.

Gadd

Yup... I didn’t consider the fan update.... Kento has the best idea yet.

gpracing

Right! This is what I thought initially. But will bypassing the relays entirely produce "high" rotation on the fans? I stands to reason that it would, but I wanted to hear a few opinions first.

jeremyb

Isn't that what you want?

What Mahjik explained is exactly what you are asking for am I correct? All those relays are there for a/c, temp switch, etc. Since you have a race-only FD, I'm assuming all of that is removed. Just do what Mahjik said, that's exactly what you asked for, hard-wiring.

Jeremy

gpracing

I'm not really clear on your suggestion. Are you saying that I should hard wire the relays, with the correct high relay setting? So this suggestion would basically be the same as GADD's and DALECLARK's, right?

gpracing

Yes, I want the fans to run on high at all times. This is exactly what I want. But, my reply question was, does hardwiring the fans at the motors produce HIGH rotation?

CANRX7GX

iTrader: (1)

Yes sir it does. I have the fan switch done to my car and it's either high or none. There should be a thread on the wires to splice and merge. It works

Gadd

The fan have four wires going to them. one is the ground (the black one) If you power the other three you have high. I'd use the stock relay myself but. one big aftermarket relay would work too.

gpracing

Great. Do I need to add a relay though like GADD suggests?

Gadd

My suggestion is to use the stock relays and modify the wiring harness so that the fan system is divorced from the rest of the car and is controlled by a switch in the cockpit. The stock relays are the right size for the fans and are reliable, but the best part is there free.

Kento

I would recommend it, because the fan motors pull a lot of amps (especially if you're going to run them on high speed), and immediately transferring that much current through just a switch will create a pretty good arc, eventually causing the switch to weld itself together.

FNQuick

I have a 94 and wired the two relays together as the fan mod suggests. Later, after installing the miata switch the fans would turn on about 5 minutes after shutdown and run for 15-20 min eventually killing the battery. Disconnecting the wire between the two relays solved this problem (islolating the fan mod as the culprit). Then I noticed simply grounding the ECU fan wire would run the fans at anytime (engine on or off). So I just used this with a ground switch for anyime fans, and make sure I turn them off at shutdown so they don't run till the battery dies. This would be a quick easy solution for you to try.

gpracing

I don't understand how the relays act as a buffer when the switch is flipped. Wouldn't the same amount of current be drawn at the switch regardless of whether the current passed through the relays? Or will/do the relays dampen the amps to the switch? I'm probably wrong (no electrical genius), but aren't the relays just switch/sensors that actuate when a particular signal is sent by the ECU, and depending on which relays the ECU activates, the fan moves at low/medium/high speed?

Gadd

The fan relays are switches with high amp contacts that use a small electromagnet to "flip" the switch, the electromagent can be powered by any low amp switch

Mahjik

iTrader: (1)

You can just do this one:
http://rx7.voodoobox.net/howto/fanswitch/fanswitch.html

It's basically what you want.

KevinK2

I'd use a 30 amp relay for ea fan. Here is circuit link

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

gpracing

I had already seen this.....not what I want. He has a switch that turns the fans on, but still relies on the ECU to manage the need for speed. And since my car has the AC removed I'm afraid this trick will only yield medium speed at best.

Mahjik

iTrader: (1)

Take a read at the link:

So, with that information, you can have a switch activate all four relays at the same time to give you HIGH fan speed.