build your own shift light, or get ripped off by ebay misadvertisement Options

[CilverSeliST205]

http://cgi.ebay.com/ebaymotors/SILVER-BLUE...609165518QQrdZ1

Above link sends you to a product called universal 3a racing shift light, which is not so universal since it needs a aftermarket 3a racing tach to work, but the seller "forgot" to mention it...

anyways, i ended up paying $25 for a aluminium tube with 4 led in it Can not return the product so i got to make it work.. here is how i want to do it:

OEM tach gets an input voltage corresponding to the rpms(please correct me if im wrong) if i run a variable resistor from that input to the base of a transistor that would switch 9V to the LEDs, then I will start the car and set the resistance to the low end and rev the car up i will get enough current to the base of the transistor to switch on the LEDs in shiftlight somewhere in low rpm range... then with increasing resistance i will get the LEDs to go on later in rpm range, and that is how i am going to adjust.

Am i going to make the tach read unaccuratley? Does tach input wire uses voltage as the only reference to rpms? Is this going to work at all? Thanks for reading/responses!

[sugarfree]

what about this i know its a stupid name, but it looks like it has a green wire.
http://cgi.ebay.com/ebaymotors/BLACK-Alumi...1QQcmdZViewItem

[CilverSeliST205]

what about this i know its a stupid name, but it looks like it has a green wire.
http://cgi.ebay.com/ebaymotors/BLACK-Alumi...1QQcmdZViewItem

LMAO "BLACK Aluminum SHIFT LIGHT TURBO BLOW OFF VALVE" that is indeed a stupid name for a shift light, but looks like it could work so try it out and let me know if it works

Anyone wants to show me the connector pinout for gauge cluster where i can see rpm signal wire? I'll try to come up with something and if it works that means anyone can build in a shiftlight for $5 and mount it anywhere where you can fit a LED... now one in the cluster with some factory look to it would be nice...