Is our ignition systems Square or Wave signal? I can't find this anywhere in the manual!!!!

I am asking because I bought at a Tach from glowshift. When I hooked it up initally I got readings of 2K at idle! I have the switch in the back set to V8. Glowshift says I don't need any adapters because I have it installed on the negative side of the coil. Any ideas as to why a gauge may do this?

This is what the Tech from Glowshift said.

"Again, I am warrantying this gauge as a precaution, and I have tested the unit and this new unit is working fine as well, I will get this shipped out, if the still reads high at idle, then there is some type of interference issue with your vehicle or your timing may be slightly off, but going to the negative side of the coil is the correct location and there is no adapters needed for your application."

They are sending me a new one, but they said the old one tested fine on 2 cars and their computer system. I had a ProTach installed for the last five years and it never gave me any problems. Anybody have any trouble with Glowshift Tachs?

 

That should work.... coil ground is either on, or off. Nothing in between. (square wave)

 

That is what I was thinking as well. I mean it is so simple I don't possibly understand what could be messing with it besides a faulty gague. My only other theory is electro interference from something but I can't imaine what. My power source is the cigar lighter. I do have another gauge, tranny temp, hooked there for power. Maybe if this new one doesn't work for me I'll hook them to different power sources? Anyone with other ideas?

 

Power source shouldn't matter. And I also don't see what could possibly be interfering with the signal to throw it so far off. You don't have an MSD ignition hooked up in there by any chance do you?

 

No, still the stock coil actually. Only thing I've replaced on the ignition is 8mm MSD wires, Champion plugs, rotor and advanced rotor and cap.

 

I suppose you could try re-routing the tach wire.... but, I wouldn't hold my breath expecting that to change anything.....

How is the tach set to determine how many cylinders you have? If it's a dial, is it just pointed in the wrong direction????

 

It has a switch on the back that you set to either 2,3,4,6, or 8. I had the other one set at 4 the first time I cranked it up and it read 3K RPMS. Then I realized I had to set it to 8 and that brought it down to 2K RPMs. Maybe that set something off in the original one.

 

Didn't change it while is was running did ya? Or, while it was still powered? (do you have a switched power source for that??)

Verify the switch position.... sometimes the 'guide' isn't exactly accurate.....

 

Maybe?? I don't really remember to be honest. It is wired to a switched power source (Cigar lighter). The switch on the back does feel quite cheap to be honest.

 

Check the switch then...... that seems the most reasonable cause at this point....