S14 SR20 ECU Fan control

[Crazyced]

I will be wiring some Altima fans and was looking into getting the ECU (69F00) to control them using the feature pack.

I have a couple of questions though. Those ECU pins pull ground right? If so, is it safe to have them drive a 30A Nissan relay that is connected directly to 12v power on the other side? Or should additional resistances be used? I don't want to damage it.

Second question, how do those HI/LOW (LHD/RHD) pinouts work. Is only LHD grounded for LOW then both LHD/RHD grounded for HIGH (or vise versa)? Or is only one pin ever grounded at a time? I hope it's the former.

[Matt]

Each fan lo/high has an output driver to drive a relay. It should not matter what the relay itself is rated to (since that just specifies the width of the contacts used in the relay, rather than the coils which make the relay work) so it will not over drive the transistors switching it on

Both lo/high are driven to ground (other side of relay is 12V+ from ECCS relay power supply)

69F00 ECU will use the 74F0F feature pack (compatible firmware)

[Crazyced]

Each fan lo/high has an output driver to drive a relay.

So does that mean that the low and hi relays are not triggered ON simultaneously? The reason I ask is because the Altima dual fans have 2 circuits going to each ones and the way it works is that if one circuit is powered on each, they will run in low. If both circuit is powered on each, they will run in high.

Am I correct in thinking that with this setup I would have to connect 1 DPST relay to the ECU's low output, then connect another 2 DPST relays to the ECU's high output, so that it can trigger both fan's high speed (4 circuits total)?

[Matt]

First low fan will turn on, and then both low and high fans

You would connect one DPST to each ECU output, resulting in two outputs (for low) and two outputs (for high)