AutoMeter Tach/Issue
 

I have a 5" AutoMeter tach (Sport Comp) all wired to a MSD6AL correctly. I turn on the key, it RPM needle goes backwards & stays there. I have re-wired it, checked everything, etc... anyone ever have this???

Sounds like the tach is fried.

Send it to autometer, they'll fix it, usually free.

Cp

be careful--mine shorted out & fried my wire harness,autometer has a program to refurbish your guage if you send it to them. alot of folks don't know it.

:o I DIDN'T KNOW THAT!!!!!!!!!!!!! :x :x I usually throw stuff like that away and get a new one....

Good to know Jeff. Thanks!! I am going to do that. Scooter

Reply
 

Some things many guys don't know about these newer tachs is,
1. when they install them in there street car with stock wiring and a radio.
2. use an MSD ignition box.
3. Use a crank trigger

This info may pertain to some, most, or all of the MSD ignition boxes out there.
Some MSD boxes if not all of them provide a square wave 12 volt, 20% duty cycle signal for a tachometer. If the tach does not operate properly and reads erratic, a tach adapter may be required.

If you are using the White wire to trigger(points input)you will need adapter PN 8910 If you are using the magnetic pickup, PN8920 will be the right adapter.

Most tachs have a green wire that connects either directly to the ign. box, or connects to a specific colored wire coming from the ign box depending on which box you have.

Some times when you shut off your engine also, the needle does NOT go down to zero, and this is normal.

Another tidbit of info is, if you are running a crank trigger, you may need a shielded wire harness with a built in ground strap to block radio interference from other wires.

One thing a bad a$$ wiring guy nicknamed "Sparky" told me was this, NEVER used your stock frame as a ground!, and always run a seperate 10 gauge or larger wire to where you want to put all your grounds at, same with a power wire, use one power source and pull power from there and don't rely on that old stock frame to carry the current as it moves literally!!! :shock: Once I changed this on my chassis with a stock frame, everything changed and worked to the T! Hope this info helps a little

Elkymann
John