Hey guys

i was working at installing a few gauges in my truck because my factory cluster has a few issues. I ended up going with GlowShift 7 color white series.

while I was installing the others, I figured now would be the time to install a tachometer too. As my truck was an xl and does not have one in the cluster.

truck is a 94 f350 with the 460 for reference.


I purchased a diesel tachometer, as it tops out at 5k rpm vs their gas tachs that go to 10k rpm… which I didn’t want for accuracy sake.


I have the gauges all wired up and powered, work great….. but, I cannot get my tachometer to read an accurate measurement. It reads very low. It will even read the exact same measurement if the signal wire is not hooked up, which I don’t understand.


on the back of the diesel gauge there is a dial 0-9. Which is used to adjust frequency. But, on a gasoline tach, they have the exact same dial to adjust for # of cylinders, 1-10. I have mine set to 8.


here’s my question, am I wrong for thinking that a diesel tach will work in a gas motor? And what is the reasoning? I assumed that hooking up to the negative side of the coil would work exactly the same.

2, what’s the best way to tap into the negative side of the coil on these trucks? I only see 2 wires and I am assuming it is the tan wire because when I hook to the red(positive) there is 0 reading on the tachometer.

3. I have also read that the factory wiring for an in dash tachometer already exists. Would it be possible to just tap into that already existing line?

thanks for all the help I am limited when it comes to this stuff.

 

I would think that a diesel tach would not work on a gas engine.

I would also think that I would reach out to Glow Shift for an answer.

I have read that some people think this company makes junk. My experience is the first one I got was. The green LED did not work. They were quick to send a return code but I was too busy to do that. The gauge did last for 15 years and I swapped it out just to get green again. After a couple years, I swapped that out because I had some E4OD transmission issues and they made a gauge that has pressure and temperature. I am glad I did. Withing a few miles, I was able to get the information I wanted and resolved my harsh shifting issue with just some programming.

 

Not sure but that tach might work like the pizo electric ones on an I/M machine
They can just sit on the motor and operate
But they are wrong most of the time the first time you set them down
If you set them down a few times, the thing resets the frequency each time
When it starts to read accurate, you leave it there
I would just toggle yours 1-9 and see which one reads right