Dbeck002

ok i am about to install my autometer tach. its pretty straightforward but there is jsut one thing i dont understand.

4 wires come out of the tach
black wire= grounded
green = MSD tach output
white = dash lighting
red = key on power


i took the underside of the dash off and looked at the key switch, like 500 wires come out of it, which do i splice into for the key on engine off power line? ahhh, too many to cut too little time.

roundman

it's easier to go to the fuse panel and use a test light to find a wire that goes hot only when the key is on and then splice into that wire.
another way is to splice into the power wire for the radio if it is accessible.
also good idea to add some wire to the black ground wire and ground it in the engine compartment directly on the block where the negative battery cable is connected to it. also don't cut or shorten any of the wires, you never know if you're going to move the tach later, so keep the excess wire length and just tuck the excess up out of the way with a twist tie or wire cable tie. don't forget to add a fuse in the power line to the tach also, 4 amps is what I think they recommend for this. you can get this at the auto store, they sell fuse holders in various gauge wires with about 6 inches of wire attached. just splice one end into the power source and connect the other end to the red wire going to the tach. install the fuse and you're in business.

Dbeck002

THANKS ROUNDMAN!!!! btw i went to radio shack today and bought a 4 amp fuse becuase the instructions said i needed one. ill go work on the tach right now. thanks again.

bobby

let us know how it goes

Dbeck002

ok i found a fuse that gets power when key is on, this may sound like a stupid question but which line do i cut into lol... there are 2 wires coming out the back of the fuse panel from this one specific fuse, which do i splice.....


<--- dumbass

4fit?

The wire doesn't HAVE to come from the fuse box. You already have the bottom of you dash off, so just turn the key on and prob a few wires with your test light. When you find one that lights up, turn the key off. If the light goes off, voila! Splice into it. I also recommend not "cutting" the wire. Get some splice connectors from a local auto parts store.

Dbeck002

ok i finally installed the tach but it wont show the correct RPM it just sits at the predetermined shift point. what the hell is going on? i connected the green wire to the MSD tach output, white wire to lighting (that works) red wire to power key on and black wire to ground. i know the ground wire and white wire works or else the backlight wont come on. it must be the green or red wire, everything is hooked up though i dont know what it could be.

roundman

check the power lead and make sure you are getting full voltage to the tach, at least 12 volts. if not, move the power wire to another source of power and see is this helps any. quick check, run a jumper wire straight to the postive battery connection at the starter solenoid and see what if anything this does for it. if it works OK directly connected, then the power source needs to be moved.
also make sure the connection to the MSD box is a good one, make sure the spade connector fully seats into the hole on the end of the box and is making good contact and that the connection you made to the supplied jumper wire is good and tight too.

Dbeck002

i am getting 12 volts to the tach. i suspect there is a malfunction with the MSD box, i dont know if its that for sure but the tach sits in 'sleep' mode as if the key on engine off even when the engine is running. its definately the green wire, i checked all the connections and they were good, i dont know what else to do but to open the MSD box and look for signs of damage.


I'm going crazy i want a working tach!!! AHHHHHHHHHH!!!!!!

P.S I bought the car with a non functional stock tach so i never knew engine rpm, this will be the first time i can monitor rpm, someone help me!!!!

Dbeck002

AAAAAAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHHHHHHHH!!!!!!! !













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