MSD Digital Window Switch/Nitrous wiring setup
 

I am trying to install my MSD dig. window switch but the instructions are not specific to our cars. I've mounted it in the glove box but that is all I've accomplished. I believe the white wire goes to the ECU Pin # 26. Black goes to ground, red goes to 12v source, grey is not used, yellow goes to nitrous solenoid? I have a warmer and my NMU ran through 1 relay that is powered by the battery. Can I just add the window switch to that relay? Sorry but MSD's tech support is teh suc! Thanks, Matt

Re: Installing MSD Digital Window Switch
 

I use one relay for the NMU and WS.

NMU: Blk wire to gnd/ Red wire to Relay #87/ Wht to TPS

WS: Blk to Gnd/ Red to 12V switched/ Wht to pin #26/ Yellow to FPSS and from there to Relay #85.

Relay: Red to Batt/ #86 to N2O switch

Re: Installing MSD Digital Window Switch
 

Yelow to nitrous\fuel solenoid relay ground. The window switch can't handle enough amp's to be hooked to the solenoid.

Re: Installing MSD Digital Window Switch
 

Thanks everyone! So where does the yellow wire go? To the fuel pressure safety switch? or to #85? or fuel&N20 solenoid ground on relay?

Re: Installing MSD Digital Window Switch
 

However you grounded the low amp side of the nitrous solenoid relay, you need connect that wire to the yellow wire on the window switch.

All the yellow wire does is allow a ground path to the wire/device connected to it when the rpms on the window switch are within what you defined.

Tony

Re: Installing MSD Digital Window Switch
 

I see. So the yellow wire is what actually enables and disables the n20. So can I ground the switch by the ecu (the ecu's ground), get 12 volt source from relay, white to #26 pin and yellow to ground of n20 solenoid?

Re: Installing MSD Digital Window Switch
 

Not the solenoid, but the low amp side of the relay which controls the power to the solenoid.

If you ground the solenoid through the yellow wire you will blow up the window switch.

Tony

Re: Installing MSD Digital Window Switch
 

Good thing I ask. I think I got it now. Thanks for all the help.

wiring diagram for nitrous setup
 

Here's a jpg of the wiring diagram i plan to use for my nx efi nitrous system install. If anybody sees anything that seems wrong please let me know. I plan on beginning install tomorrow and will post some pics tomorrow.

Re: Installing MSD Digital Window Switch
 

OK Bill which one is it no or yes? The warmer does have a thermostat to turn off automatically.

Re: wiring diagram for nitrous setup
 

Here's some pics of what i got done tonight...i'm just trying to mock up everything. Both of the 'noids are going to be mounted near the firewall (one using the shaker mount, and the other using that little tab on the top of the passenger side firewall.) Nozzle placement was a PITA because I just have the stock air intake tube right now. I will probably go to a different air intake setup later, but for now I'm making do with what I have. I'm not using the nozzle adapter because it was too short to screw into the sharp radius of the stock air intake tube. Instead I just tapped the tube and am screwing the nozzle in directly and will use RTV sealant around it. It feels pretty sturdy but we will see. The wiring begins tomorrow so if anybody sees anything odd about my wiring diagram in the first post please let me know.

Re: wiring diagram for nitrous setup
 

Thanks alot man. I hope I have the relays figured out so I don't blow something up....:eek:

Re: Installing MSD Digital Window Switch
 

So you guys are wiring the window switch into the ECU? The directions say splice into the coil wire and setup for 1 cylinder for our cars. If you do it your way do you set it up for 8 cylinder?

Re: Installing MSD Digital Window Switch
 

All of the coil wires lead directly to the ECU. I did this and appears he did too, but we tapped one of these wires on the negative side then configured the Window switch for 1 cylinder mode.

Tony

Re: Installing MSD Digital Window Switch
 

That makes sense. Thanks.

Re: wiring diagram for nitrous setup
 

Thank you for the wiring diagram. Saved me a lot of trouble. Hope you don't mind if I steal it :ANGEL:

Re: wiring diagram for nitrous setup
 

The only thing I see that worries me a little are the 40 amp fuses. Unless you are running everything through 10 ga wire, you might get a fire before the fuse blows if something shorts to ground.

When we did Mike's we used a 30A for the bottle heater ckt and a 20A for the rest.

Re: Installing MSD Digital Window Switch
 

OK I've got everything hooked up except the yellow wire. I'm confused about where the "low amp" ground is you are referring too. Doesn't the yellow wire basically make a ground for whatever it is you are windowing? Can I just hook the ground for the NMU directly to the yellow wire? It seems that this would complete the ground for the NMU and activate it between the programmed window.

Re: Installing MSD Digital Window Switch
 

I merged SheaSanford's nitrous wiring thread with this one, since the same issues are being addressed in both. Hopefully this merger will help everyone.

Re: Installing MSD Digital Window Switch
 

The "low amp" ground refers to the ground for the relay coil. The coil of the relay uses very little current, so you can connect that directly to the yellow of the window switch. The "high amp" or switch side of the relay can support loads like solenoids, bottle heater, etc.

When the window switch activates (RPM is between low and high RPM setpoints) the yellow wire supplies a ground to the relay coil. The other side of the relay coil is going to be hooked to +12v power, possibly through an "arm" switch and a WOT switch, and maybe a fuel pressure switch, depending on how you wire it. Alternatively, you could put the WOT and the FPS in series with the ground side of the relay, it will achieve the same thing.

The basic thing is, you want the coil of the relay for the solenoids to be in series with the window switch, the fuel pressure switch and the WOT switch, and the ends of that chain connected to switched 12v and ground.

SheaSanfords diagram shows this pretty well.

Re: wiring diagram for nitrous setup
 

If your FPSS is not hooked up as a ground for your N20 solenoid how is it going to be effective in shutting down the N20 when the fuel pressure drops? Or is it going to be working through the window switch? Man this shiate is confusing. I think I'm more confused now than I was when I started.

Re: wiring diagram for nitrous setup
 

So I can run the yellow wire to the FPSS and run the ground that comes from the NMU to a regular ground instead of to the FPSS?

Re: wiring diagram for nitrous setup
 

The way I see it is..a relay works the way you want it to. It takes two low current sources to "energize" the relay which then flips the switch so the high current lines are activated. In my case...there are three parameters that must return "true" for the low current sources to energize and flip the high current. Those parameters are the WOT switch which is directly connected to the relay. Then there is the window switch which is in series with the FPSS. You must be in the desired rpm range for current to flow through the yellow wire, then fuel pressure must be adequate to keep the current running all the way back to the relay. Thus, you have all your parameters satisfied, and the relay is energized and 12 volts supplied to both solenoids and hopefully you go really really fast!:gears:

I haven't gotten to making the connections yet (still trying to get the fitting out of my fuel rail test port that was evidently already broken off when I bought the car). But I'll let you know if anything goes wrong with my setup.

Thanks hawkpilot for the merge and the fuse selection. I will be taking your advice and using 30A for the heater and either 20 or 30 for the main stuff.

Re: wiring diagram for nitrous setup
 

Here's how my nitrous system is hooked up:

http://www.mach1registry.org/forums/...4&d=1138055862

See how the yellow wire on the window switch completes the ground from the low-amp side of the relay? The way it works is, the solenoids never get their 12V of power until the low-amp side of the relay has a complete circuit.

Tony