i want to make some kind of LED shift lights that fit in the gauge cluster (like the multi-colored nsx-r shift lights). i've been searching and it doesn't seem like anyone has really accomplished this without buying some kind of expensive shift light an taking it apart modifying it. i have an apexi VAFC, which has a shift light function. so i was just wondering if anyone knew of a way to splice into the VAFC, or tach signal wire, and be able to have functional sequential shift lights? i would like to have 3-4 LEDs ranging from green to red, all lighting up between 7k rpms and 8k rpms (h22 motor has rev limit @ 8k on stock tach). TIA for any input.

 

word me too i just bought a regular little LED from a auto parts store the kind that looks like and alarm light and i wanted to have that as my shift light because i didnt want a large one

 

went and measured voltage of the "tach test connector" found on the passenger side shock today and got fluctuating readings. if the tach reveives a pulsating power supply, shouldn't the voltage readings pulse too? instead i got readings that hold steady, and gradually increase as the revs climb. either way i think i have found my power source for my project.

are there any electrical engineers out there that can help me think of a way to light up 3 or 4 LEDs in sequential order as the revs climb between 7k-8k rpms? thanks! i need some kind of relay/switch that is activated at a selected voltage, then i could just rig a few of these to light up the LED at the coresponding voltage desired.

 

How about using an MSD rpm switch.

Here's what you could do:

The rpm switch uses those little pills that I would guess are resistors of some sort.
So you should be able to run wires from the two inputs on the switch itself and do the following.

I would assume the way the resistor or whatever works is that the signal goes in one side and if the voltage is high enough to pass through the selected rpm/resistor then it goes through the other side.
Kinda like the way a fuse works but almost backwards?

So what you do is link one side of the wire from the input/output where the pill would normall go to one side of the pill. Then from the other side of the pill you run a wire to one side of the led. then run the other side of the led back into where the other post on the pill would go?????????????????

Maybe that would work? Then you just run power to each of the other pills in the same way with different color leds and they should light up?????????

I am by no means an electronic engineer and have no idea if this would even work, but I guess its worth a shot right????

Hope this helps or maybe spauns other ideas.

***** Send me a PM if you would like me to draw a diagram and post it to clarify what I'm saying******

 

ok so i have some good and bad news. good news first: i found a tach signal voltage ouput on the ecu that changes with the rpms. i think i can use this wire to trigger the shift lights to come on.

and the bad news, the voltage is around 10 volts at idle, and the voltage decreases as the revs go up. this means that a simple relay-type trick wouldn't work. as the revs climb, the voltage drops, and the relays won't have power to switch over. the LEDs would be on at idle, and turn off one-by-one as the revs went up.

so now i need to re-think my plan and redesign everything because i had devised a way to pull this off assuming the voltage was going to increase with the revs. any helpful input is welcome!

 

The sequential lights that illuminate and stay on throughout the RPMs are a bit harder to make than one light that turns on at a given RPM.

I have been working on a sequential boost gauge that illuminates LEDs with increasing boost. I have yet to probe the RPM signal but you say it decreases with RPMs? I have a datalogger, when my car is up and running I will certainly log some runs and look at the RPM signal.

I dont imagine the circuitry would be too much different for the boost gauge than the RPM gauge. Have you opened up an adjustable shift light before?