i installed an autometer tach in my 93 dx hatch. I connected the green(signal) wire to the blue wire under the hood right next to the firewall on the drivers side. I read that in some how to thing. of coarse i connected power, ground, and light wires as well. The lights on the tach work fine and the needle on the tach moves when i rev on it but its not correct. ie. when i know im at well over 5k the tach only says like 3 or 2.5k. im thinking it could be from a bad ground but im not for sure that would result in my problem. any help?

 

Check the ground, maybe try re-grounding it somewhere else. Also does that blue wire lead to the coil? If so maybe try putting your signal wire closer to where it comes out of the coil to get a better output signal.

 

if its a four cylinder you got to cut the blue wire on the back of the tach. if its a six i think you cut the brown and if its a eight you got to cut both. so out of the brown and blue wire on the back of the tach cut the blue one and that shuould solve your problem.

 

i think if its a v8 you dont cut any, v6 cut brown, and 4 banger cut both. thats how mine was

 

what guague you got? i got a phantom series 5" monster tach with shift light and i had the not reading correct problem at its first install but cut the blue one and its working fine ever since.

 

there are only 4 wires. red(power) black(ground) white(illum) and green(signal). so i dont know what your talking about cutting.

 

look direcly on the back of the tach (the cup part) and you should see a blue and brown wire.

 

I had this problem. Im assuming with the wires your naming that your tach is a small one, like one i had. The signal wire (green) connects to to the blue wire like you have, but you say next to the firewall? Well it should be the same blue wire coming out of the coil on the dizzy. You want to connect that green wire as close to the blue wire on the coil as you can to get an accurate reading. That was my problem when i installed mine.

 

thanks, i think thats probibly the problem. i'll re wire it tommorow. thanks for everybodys help.