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looking to retire my msd pill activated rpm window switch and picked up this jegs digital window switch (http://www.jegs.com/i/JEGS+Performan...40824/10002/-1)
I have a quick question with the wiring, if someone can chime in...
Jegs instructions
Installation:
• Red wire attaches to a switched +12 Volt supply source.
• Black wire attaches to chassis ground.
• Grey wire is input for the Tachometer signal. This wire will hook up to the negative side of your ignition coil, or if you
are using a high energy CD ignition, connect to the TACH output of your ignition system to the Grey wire of the
RPM switch and NOT the coil.
• Blue wire connects to the negative/ground side of the device that you want to activate at the desired RPM. This
connection is either Normally Open (Blue wire provides ground AFTER the switch reaches desired RPM) or
Normally Closed (Blue wire is grounded UNTIL switch reaches desired RPM) according to the setting in program
mode (OFF means Normally Open and will supply ground when the selected RPM is reached, ON means Normally
Closed and the switch will open when the selected RPM is reached). Factory default is Normally Open.
My wiring looks like the picture minus the FPSS. Could I wire the Jegs window switch like the MSD? But blue to ground side 85 of the relay and grey to the PCM tach wire... and set it to 4 cyclinder mode, etc,etc .. Car is a 01 c5 A4 with nitrous outlet 100 wet plate setup
mucho thanks
Hey guys sorry to bump an old thread but I am having a hell of a time getting my damn window switch to read correctly. Just like the OP I have the jegs installed on my e30 bmw and rpm bounces around like crazy (not even remotely accurate) or doesnt even show up at all. I have tried the white tach output from the PCM and that gets it to read RPM but it is not even close. Then I tried to tap in the light blue/tealish wire on the coil (See picture: The one that is pulled out to the side on left) that also gave me the crazy bouncing around rpm, and then i tried the green with white strip (one on the back right in picture) wire and the window switch just goes through is programming mode as if the car isnt started. The window switch is wired just as the instructions in the above post. It is set to 4 cylinder mode. Any help would be greatly appreciated.
The wiring of the switch itself is good to go but I can't believe you've had so much trouble getting a clean tach signal. Especially when going off the coil pack, but I've seen some crazy things happen with electronics.
I know you have probably tired this but you didn't mention it in the post....
Have you tried going off the TB itself? < For some reason I thought the switch had a TPS hookup but it looks like it doesn't >
Also when making the connections are you using T taps/ bunt connectors or are you soldering the connections?
-Chris
Last edited by NitrousExpress; Mar 9, 2015 at 08:52 AM.
Hey guys sorry to bump an old thread but I am having a hell of a time getting my damn window switch to read correctly. Just like the OP I have the jegs installed on my e30 bmw and rpm bounces around like crazy (not even remotely accurate) or doesnt even show up at all. I have tried the white tach output from the PCM and that gets it to read RPM but it is not even close. Then I tried to tap in the light blue/tealish wire on the coil (See picture: The one that is pulled out to the side on left) that also gave me the crazy bouncing around rpm, and then i tried the green with white strip (one on the back right in picture) wire and the window switch just goes through is programming mode as if the car isnt started. The window switch is wired just as the instructions in the above post. It is set to 4 cylinder mode. Any help would be greatly appreciated.
yea man that wire on coil pack wire, was no good for the tach signal. I ended up using the white wire from the pcm and it worked fine, and like nitrous express said check your connections for clean solders, don't trust the add a tap wire plastic deals. Also if I could add make sure your ground connection is good. I also tossed the jegs window switch and picked up a msd digital switch. hope this helps man.
The wiring of the switch itself is good to go but I can't believe you've had so much trouble getting a clean tach signal. Especially when going off the coil pack, but I've seen some crazy things happen with electronics.
I know you have probably tired this but you didn't mention it in the post....
Have you tried going off the TB itself? Also when making the connections are you using T taps/ bunt connectors or are you soldering the connections?
-Chris
I have not tried going off TB which wire should I try tap into for that one?
Also Ive read conflicting things on which wire from the coil I am supposed to tap into. Is it the lt blue or the green with white?
I have been using T taps which is probably part of the problem, I will soldier the next time but I want to make sure Im tapping into the correct wire.
I have not tried going off TB which wire should I try tap into for that one?
Also Ive read conflicting things on which wire from the coil I am supposed to tap into. Is it the lt blue or the green with white?
I have been using T taps which is probably part of the problem, I will soldier the next time but I want to make sure Im tapping into the correct wire.
Thanks guys
the wire from the coil was tealish with a white stripe... here is a link to another thread that shows the tach wire on a c5 corvette im going to assume its the same for all ls1 coil packs.... https://ls1tech.com/forums/nitrous-o...ed-wiring.html total stole the link from beer99 hope he doesn't mind.
good luck man....
Gotcha so I looks like the lt blue/tealish wire though mine does not have a white stripe (second from the left top side) is the correct wire. Guess I need to go in there and soldier to see if it will work
Go off the main coil pack plug female side on the passenger side. There will be two row's of wires. You will need the top row < Row closest to you > and it will be the second wire from the back < or second wire from the left >. It should be a solid green wire or a light green wire w/ a white tracer.
Also for the TB TPS wire I believe it's a blue wire. < For some reason I thought the switch had a TPS hookup but it looks like it doesn't >
-Chris
Last edited by NitrousExpress; Mar 9, 2015 at 08:51 AM.
Hey guys sorry to bump an old thread but I am having a hell of a time getting my damn window switch to read correctly. Just like the OP I have the jegs installed on my e30 bmw and rpm bounces around like crazy (not even remotely accurate) or doesnt even show up at all. I have tried the white tach output from the PCM and that gets it to read RPM but it is not even close. Then I tried to tap in the light blue/tealish wire on the coil (See picture: The one that is pulled out to the side on left) that also gave me the crazy bouncing around rpm, and then i tried the green with white strip (one on the back right in picture) wire and the window switch just goes through is programming mode as if the car isnt started. The window switch is wired just as the instructions in the above post. It is set to 4 cylinder mode. Any help would be greatly appreciated.
Definitely double check all of your connections. The wire on the coil pack connector should work on all LS vehicles.Top row of wires, 2nd wire from the left on the main coil harness plug. Have you tried tapping into an injector wire? Put it on the 8 cylinder setting if you do. The blue wire on the throttle body is for TPS. Not tach signal.
You'll need a tach adapter to make that specific window switch work on your application. You can pick one of ours up and it is actually a TPS/RPM box. (Dual function.) What Chris said about the wire color is correct.
Here is a link to ours, send me a PM if you need forum pricing on it.
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Jegs window switch ??? 
