Tach Dash

[Wootdog]

I was looking over some posts that I frequented awhile ago about a tach dash. Well I can not find who I bought it from. It doesn't work. I would like to know what the resistance is supposed to be with a multimeter to be good. I am showing an open. It doesn't matter how I connect it, it don't work. Showed 800 rpms the first time I fired up the truck and nothing since. And the temp gauge don't work either. The amp gauge and the fuel gauge do though. Just venting Kerry.

[JimKshortstep4x4]

I took some readings off of a working tach. Coil to ground is 3.37 m ohms.
12v post to ground starts out at a very high reading and goes to infinity, (open). It must have a capacitor in the circuit because the way to get a reading is to read coil side first.

I suspect that checking with an ohm meter is not the way to test a tach.

Jim

[Wootdog]

the problem I have is that one side has to go to 12vdc and the other side to the computer for the LT1. I see the voltage vary coming out of the computer for the tach line. The tach looks like it went to 800rpms and then hasn't moved since. I have wired the whole truck without any problems until now. I swapped the two wires and no change also. Makes me think I am missing something. Kerry

[Wootdog]

Anyone? Kerry

[olblue60@aol.com]

I have a collection of antique tachs and guages. I have never tried to hook any of them up, but I have been warned to use a Tach adapter when hooking to electronic ignition. I dont know anything about the hookup, but there is a vendor in the Hemmings Motor News, "Williamsons" ,who is a father, son-inlaw pair with a great reputation of tack and Guage restoration,who are always more than happy to give out free advice. Great vendor,you might give them a call.

[Kleantouch]

I bought a tach dash/vacuum etc. to hook up to my 71 Blazer- I also put a 454, HEI distributor and a painless wiring harness in- When I first hooked it all up, the tach would bump with the starter, but when the engine fired- nothing- one wire +12vdc, one wire straight from the tach terminal on the hei distributor, and the tach itself grounds thru the dashboard ground. I *****ed at the guy who sold it to me, blah blah blah. Turns out my bayonet connector at the dist was not engaged on the prong- put it on correctly, tach works fine. If you have a resto dash, the tach should have two connectors- the one on the left side as you are looking at the back of the tach to the disty (or pulse source) and the right- as you are looking at the back- 12vdc, and it should ground thru the dash case- your wiring harness should have a ground wire at the plug which grounds everything. make sure you have the dash grounded- 99% of all electrical problems are bad grounds. Good luck!