autometer tach and msd 6AL box install

[northeastmopar]

I am not getting my autometer tach to run. I installed an MSD 6AL brand new. Instructions and MSD call verified I should use the gray wire coming from the msd box. They also told me the autometer tach I bought brand new needs no extra parts to make it work. Basically I have a keyed on ignition wire which checked live plugged to the positive terminal. I have the gray wire plugged on the signal terminal. I have a ground in and a graound out to the next guage and I have a dash light feed in and one out to the next guage. I think this is correct but my tach just sits there. I do have other autometer gauges such as voltage, water temp, oil pressure which all seem to work fine. And they are all jumped for ground and lights along with each power feed from the sending units. Anybody want to venture where I should look? How can I test that signal wire for the signal? Tach is on the left. White wires are grounds. Orange is lighting feed. The two empty tach terminals were wired with the gray signal from msd on top and my keyed power source on the bottom?? Isn't that correct??

 

[KitCarlson]

I assume this is the wiring. First check would be to use multi-meter to verify ground connection and 12V power. You can use meter on AC volts, to see what is happening on tach wire, it should vary some with RPM.

 

[northeastmopar]

View attachment 1714957848
I assume this is the wiring. First check would be to use multi-meter to verify ground connection and 12V power. You can use meter on AC volts, to see what is happening on tach wire, it should vary some with RPM.

Looks like what I did? As far as signal check is concerned, MSD says check the gray wire with engine at idle. Use a volt meter set on DC and voltage in the gray line should be about 5v engine running at idle. Maybe I will do that today. I guess where I jumpered all the white ground wires from gauge to gauge maybe I have a ground issue. So I may just make up a pigtail and run it directly from the gauge to a separate good ground to see if that would do anything?

 

[KitCarlson]

Daisy chain of grounds a bad idea. Grounds should star out from single ground, so many terminal are not in series. Measure the ground at tach, back to battery negative, with circuit powered. A good voltage there should be near zero.

 

[northeastmopar]

Daisy chain of grounds a bad idea. Grounds should star out from single ground, so many terminal are not in series. Measure the ground at tach, back to battery negative, with circuit powered. A good voltage there should be near zero.

That's two confirms that I may have a ground issue. My other few gauges seem to work fine but the tach may be looking for a better ground as you stated. Time for some better quality wiring. I learned a lot with this build for sure. Wiring was never my strong suit.....