my tach dosent work when the lights are on

I have my tack wired pos. to pos.battery neg. to neg side of the battey and for the light I wired it to my parking lights well I disconnected some old speaker wire from the pos. batt. and the tach pos. came off and then touched pos. again and now my tach only works when the parking lights are off and the light on tack dosent come on at all PLEASE HELP ME

Thank You
Chad

If I'm correct there should be 4 wires that run off you tach. Right? Ok if so the colors are different on all tachs. It sounds like you have the feed wire (the coil one) going to your dash lights. and the pos one to power the unit going to your coil. JUST recheck your wiring as Im writing this I know what Im saying but it dont sound right. sounds to me like ya got the wiring messed up.

yea, wireing is probably messed up, i know with my friends Autometer Tach, there are 4 wires, red=positive, black=ground, green=to dizzy, and yellow=to parking lights...... Thats how we have it and it works perfectly....... what brand is yours?

Yea I have four wires pos. neg. coil wire and light for tach which I tapped into my parking lights everything worked fine until I touched that pos wire to the battery after it came unhooked I reconnected it while still grounded. The tach works when the headlights are off but when there on I get no reading

Thanks
Chad

Oh yea its a sunpro

try disconnecting the wire that turns on the light for the tach, and if it works, you have a tach with no light! now, try follow this wire and make sure its not burnt up anywhere, cause that might have happened, if it did, replace the wire, or cut it where it got burnt and wire an extension on there, and try again...... i hope that made sense!

Thanks for all the help. I also have two autometer gauges with just the lights wired into the tach so they all ran off the same line I'm gonna go check the wire Thanks guys

Chad

no prob man, hope it all works out good, you should get a thicker gauge if you are gonna run other gauges off the same thing......

Ok I cut the wire that went to my parking lights that powered the light on my tach and now it dosent work at all

the tach doesnt work at all? like ZIP? take off the wire for your light, and see if the tach works without the light...... contact the manufactur, u might have a defective tach.... i dun know what else to tell ya!

DID YOU HOOK your light wire to the parking lights (and do it backwards) so taht when they are off the light is on and when the lights are on the tach is off? might be somthing as simple as that