Anyone ever install a rpm shift light before ?
Tried everything, MSD rpm switch with GMR inductive pick up....no go.
Tried picking up signal from injector and coil and going direct to MSD rpm switch and still no good. The factory tach lead will not do what I need as well.

Anyone have a pin out picture of the 3 wire coil connector. It's 12v, trigger, ground but need color code as I do not have any books available.

 

This? Items R4 are the plugs with the coils attached accordingly. Hope this helps.

 

Thanks man it helps ....but it is not showing specific to voltage and ground with + / -
When I test each line there is voltage on all of them when running ???
I will try again by connecting the rpm switch directly to the coil wires like MSD told me. The guy said many times "switched" power for the red wire but that is the12v source when key is on to me, not at the coil. Shouldnt make a difference.
May have to try the Holley shift light and connect to the GMR magnetic clamp-on pick up.

 

Each coil is marked as 1a, 1b, and 15. With 15= power and 1a & 1b = coil signal output (for each plug). No separate ground.

 

Thanks I will try again. I hate wiring direct to the coil to make this work because the ECU may not approve of the difference in load. You know how "smart" these ECU's can be LOL.
If all else fails I will pick up the Holly Sniper light which has everything built in and just needs a trigger to operate. Thanks again for the info man !!

 

OK it's not going to work. This MSD rpm box will not pick up the signal so will have to try a Holley light and see.

 

I may be late to the party, but here's my $0.02...

I assume you are trying to use the MSD 8950 RPM switch. The Mercedes coils take +12v in at the center pin, and each of the two outer pins fires a plug by connecting it back to ground inside the ECU. So I would pick a cylinder and wire the MSD red wire to the center pin and the white wire to either one of the outer pins. Then use the gray or yellow wire to fire the shift light as appropriate.

On a side note, you will need to fire that shift light a good bit before you hit peak RPM. I have my PCS controller set to initiate the shift 500 RPM lower than what I want the engine to see. (shift starts at 6000 RPM, engine sees max of 6500)

 

That's what I did Joe and still did not work. Even the GMR from MSD did not work but was told it won't with the 8950 for what ever reason.
I ordered the Sniper light and will try again LOL

 

Also keep in mind that the individual coils will mean that the RPM setting or pill you use may need the be 1/8 the rpm value you want the light to turn on at, because they are usually setup for a single coil for the whole engine.

 

All is well in Gary land again. Put the Holley Sniper light in and works great. Took some time to match the rpm from engine, my tach and the Sniper but she's good.