Soon I will be installing some lights that will light up when my Vtec kicks in. I do lots of racing on friday nights in my city and I want something cool that makes my car stand out. I am going to put white lights in my grill area and under the bumper. When I launch from a stop light and hit 3500 rpm the front of my car will light up when you can hear that cold air intake get throaty. I love hearing the sound of my Vtec kick in and the feel of the boost in horsepower. Now i want a visual notification of its presence.

First off I have a relay that I will have hooked to the positive wire on the Vtec solenoid. When the relay switches it will energize my circuit with my LED light strips I bought on Ebay at 24 48 96 120cm LED Strip Car Motorcycle Flexible Grill Light Lamp PVC Waterproof | eBay.

I have not installed any circutry yet but i have a potentiometer to adjust brightness and to limit current to my lights. I have an inline fuse holder and a 3way switch to turn them off completely, have them work with the vtec, or enable them so i can make sure they work lol. This project shouldnt take long but its going to be awesome

 

cool idea. you want to make sure the additional current for the relay coil doesn't affect the ECM that controls the VTEC solenoid. using a NPN transistor to further isolate the relay coil from the ECM would have been my approach.

like this

 

Ya I realized that there is a blowback voltage from the coil as it deenergizes and that I would very much not like that in my Solenoid circuit. I bought a transistor and resistor to make the circuit kind of like the one you showed. I also realized I will need the DIODE you showed. Im guessing this kind of wipes out this current from the coil. Do you have any idea what kind of diode I shoud use

 

the diode gives a path for the coil current to go when de-energizing.

a 1N4002 is sufficient and a pack is a dollar.