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Hey Guys,

im installing my Apexi RSM today and want to get the Apexi shift light setup also. there isnt a direct plug for it so i gotta splice it into the white RPM wire. therefore im thinking i need to use a relay or somthing?

any ideas guy? someone else has asked the same question a while ago but didnt get an answer.

the shift light has a plug on it but im guessing its for a gauge not an RSM.

The rsm has one triggered output. Use that output to trigger a relay, and the relay to power the shift light. I can't remember if the rsm output is -ve or +ve triggered, so you'll have to work that out yourself. I did this for a mate, in his 33.

Not sure why you need to splice it in the rpm wire, as the rsm has a output wire. You then program the rsm to trigger that output at a certain rpm.

hey "AL" yeah i figured it out thanks mate. And its -ve triggered.

easy job but would have been easier if i have the english instructions.

lots of fun with the multimeter anyway

  • 3 years later...
  • 2 months later...

Sorry to dig up an old thread, but saves me from making a new thread on the same topic lol

I've got the Apexi shift light and was wondering what relay people have used for the shift light and what do they reccomend? I typed "12v relay" into Jaycar and it came up with 20 pages worth of different types of relays so I'm a bit lost to be honest. Also, WTF is a relay anyway?

2 choices.

1. Go to Supercrap Auto..... Buy normal Hella or otherwise typical blue relay with or without fuse. Live with it clicking every time it activates.

2. Go to Jaycar. Talk to counter geek. Buy suitable solid state relay. Won't need to be a big expensive one, as shift light current won't be very much.

Thanks for the reply fellas.

Clicking won't bother me that much as the car would be on full noise anyway by the time the light activates.

Sorry for the noob question but is a relay kinda like a switch? If so, how come the one that you've linked Titan has 4 legs/connections?

TiTAN showed you a link to a solid state relay. It is a cross between a relay and a transistor. Works like a relay (one circuit that flows the triggering current, second circuit, the switched circuit, that carries your load'd current), but is built more like a transistor - out of silicon. Normal relays have a coil that your activation power runs through. Coil makes electromagnet move the switch. The switch carries the heavy current for your load. Solid state relay has no moving parts.

Hmm I see. If that's the case, why didn't Apexi just use the white wire (the one that is supposed to be connected to the relay) just fire a +ve current when the RPM is reached, and simply having the shift light earthed on one end so when the +ve is activated, it just lights up?

Because the relay system is a bit "blurry" to me at the moment lol

It's because you could get some dildo hook up a 50W shift light and cook the output transistor in the RSM. The relay decouples the two devices, so only a little current flows through the RSM's output, and you can have an arbitrarily large current switched by the relay.

Any relay able to switch the current drawn by your shift light will do.

The fuse is there to protect the cable. Whatever the wire size you have in the path (including whatever little rat tail of wiring hangs directly out of the shift light) will have a maximum current that it can carry before it gets too hot and melts/burns. The fuse is supposed to be sufficiently lower rated than that so that the fuse will blow before you destroy the wire and set fire to the car.

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