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Discussion Starter #1
I want to install a diode to run power one-way from the GoTech output to the fan-relay (to prevent power/signal feed-back in to the GoTech from that line, when I throw an over-ride fan-on switch...)

Sort of like an electrical "check-valve"...

Any suggestions? Brand? rating/ohms/watts? Whats evers... :D Standard 15 AMP circuit (fan relay...)
 

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I tend to use the 1N540x range when I do stuff like this, simply because they are physically bigger and stronger than the 1N400x family, and thus better suited to living in a loom somewhere. Nowt wrong with the 1N4005 though.

...actually, you've got me thinking....I don't know the GoTech system at all, but typically, ECU outputs are active low, so if the same is true for your ECU, all you need to do is ground the relay coil low side with the override switch and not fret about the ECU.
 

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Discussion Starter #5 (Edited)
Maybe, but it may still feed-back in to the ECU! (Don't want to take a chance! May not work and then bye-bye ECU!)

Also, the GoTech completes grounds internally via its own ground, so the switch still needs the GoTech to kick on the signal.

The GoTech itself needs a very solid ground and lots of juice BTW (since it powers the internal drivers and processor, the multi coil-packs etc and provides outputs to many other components such as the fan relay, the fuel-pump relay, tach signal, shift-light, VANOS etc etc.)

Yeah, I have decided not to go that route - just going to let the GoTech take care of the fan relay and that will be that.

You can set the ranges within GoTech and my first fire and run-up to temp confirmed that it works well - kicks on at 180-185-190. (I may bring it down a bit, but I will wait for track testing to do it.) If it is ever an issue, I can always just jump it track-side for the day and then I'll install an over-ride switch! (Nice part about building it yourself, is that YOU know where everything is!) ;) :cool:
 

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That is what I did. I put in a 2nd relay where the thermo switch was wired. I did not want the A/C to feed back and burn out the driver on the ECU. as the A/C can also turn on the FAN.

I also put on all new connectors on the alfa side and new shells. the parts are at digikey.
just like the OEM not the crap smash conectors you get at a auto store.

.250' Connectors and housings
 

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