Thread: Double check solenoid polarity

Next weekend I wanna wire up my Greddy MSS.
Just to double check and to make sure nothing goes wrong, kaboom, or goes up in smoke I'd like to know if it matters if we connect the + or - to the MSS?

Bumpitty

Subscribing for the same information as I am upgrading from twin MSD 8969's to the MSS in the Classic before she goes back on the road.

If you using a factory loom then you cut the wire that goes to the ECU from the solenoids, and hook it up to the MSS.

You MUST connect the ground ( - ) side to the MSS. The MSS (like the factory ECU) switches GROUND.

I remove the intake and exhaust wire from the ECU loom/ECU side.
Those wires I connect to the MSS then??

How do I know which one is ground and which one isn't?

I'm not cutting wires directly at the solenoids (at least not intending to do so).

AH I see. I connect the wires from ECU side to the MSS, and run wires from the + side to the according wires of the MSS.

If wires from ECU are ground aswell, that can not go wrong.

^^ NO NO NO ... Please read this very carefully so you don't end up releasing the mystical smoke from your MSS or your ECU. (not wanting to make it sound stupid, but eletrical work must be followed carefully as i don't want you to blow stuff up).

The Solenoids are provided a CONSTANT +12v supply from the battery when you are using the factory SR16/SR20VE loom on your motor.

The second wire at each solenoid then goes into the ECCS loom to the ECU.

CUT the wire (leaving a bit before it goes into the ECU Plug) and leave the wires coming out of the ECU plug, DISCONNECTED.

The wires in the loom that come from the solenoids are connected to the green and yellow wires from the MSS. That's it. The MSS does the switching and provides the ground internally. (obviously the MSS still needs RPM, power and ground connected, but that's it for the solenoid connections).

DO NOT connect ANYTHING back to the wires that are left floating on the ECU plug, tape them up or tuck them away, but do not connect anything to them, they are not used anymore.

I saw your message just a few seconds ago, the MSS is already installed a couple of hours ago and we realised all of the above while doing the work so everything went OK, it's configured OK and it works like a charm.

Much smoother to drive. Good investment, now continue on working on the mapping.