jwbronco

I'm going to try to solve the problem with driving an aftermarket tachometer with some simple, inexpensive solutions. I'd like to know what other people have tried so far. I'm curious if anyone has a tachometer they'd like to try. I haven't ordered a tachometer yet but I have autometer z series for my boost and pyro.

1. I've ordered some dc-dc converters to bump the voltage up to 12v for the signal.

2. If that dc-dc converter doesn't work I'm going to order some solid state relays that trigger off of 5 volts.



In order to make sure any of the circuits could handle the pulsing I had to break down the frequency of the pulses.

500 rpm = 1000 ppm / 60 = 16.67hz / 1 = 60ms
3500 rpm = 7000 ppm / 60 = 116.67hz / 1 = 8.57ms

those numbers are what I'm looking for switching time on the relays.

NJTman

You're over-complicating this process.

You have a connector under your dash that will provide you the signal you need for a tachometer. I just did mine, as others here have done. It took maybe an hour to install, and depending on your skill level (which by your post it seems you're quite knowledgeable) you shouldn't any issue doing so.

It's in the sticky, or you could just simply search for it.

This is the one I used...
https://www.dieseltruckresource.com/...d.php?t=173561

But you can use any tach you want to..... again, in the sticky under electrical

https://www.dieseltruckresource.com/...82&postcount=7

jwbronco

I'm aware of the connector under the dash but from what I've read it's a 5v signal and it won't drive the autometer tachometer. I'm looking at possibly $10-20 to use existing wiring and basically just splice it so the factory signal is the input to the dc dc converter or the trigger for a relay.

Jim Lane

Or you could use an ultrasonic transducer and pickup the sound of the injection pulse from the injection line,
Or a Hall Effect switch and magnets off your harmonic balancer, or count the teeth off the ring gear like a tone ring would do.

Don't think the duty cycle of a relay would handle that many pulses for very long.

The Dakota Digital adapter is almost too easy.

Jim

ChrisLib

Why not just use the Autometer alternator tach, super easy to install and you already have the matching boost/pyro

taterfarm

I have used the cheap sunpro super tach in four trucks now, its about $25 at most any auto store. Set it on the 4 cylinder setting and plug it into the wire harness under the dash. Hard to get much simpler or inexpensive.

Mark Nixon

A buddy of mine just put an Equus(?) tach in his 1992, with the cylinder mode SET ON 4 CYLINDER and it works just fine.

I believe if the tach is designed to run with the MSD igntions (which have a tach signal port), it will also work on the system in our trucks as well.
BTW, once again, if you try this MAKE SURE IT"S ON "4 Cylinder" or it will read way off.

I'm sitting on several "OEM" tachs, so I don't need to worry with making something work.
Just need a truck with the harness to put one in.

Mark.

jwbronco

That's exactly what I was looking for, now that I know the output of MSD is low like the factory one I can just buy an MSD tach converter and be good to go.

I knew that I had to set it to 4 cylinder due to the stock fires 2 times per rev just like a 4 cylinder because only 2 cylinders would fire per a complete revolution.

I just really want to hook up the Autometer 2697 http://autometer.com/cat_gaugedetail...id=3239&sid=12 to match the rest of my gauges.