supra rpm meter

[sylph]

hi any1 can sum1 help me out on this, i just converted my n/a supra into a single turbo, all went gud, except now my rpm meter in the gauge cluster is dead, the light works from time to time, wen i hit a bump or when am driving on a rough road otherwise my rpm remains at 0 even tho i m pushin it, my car is an auto but it still bothers me that the rpm doesnt work, any1 can give me some advice ? cheers