I've been looking and looking, and I have not been able to come up with anything. I have a 94 cummins tach sensor and harmonic balancer on my 4bt. I have also ground 2 more notches into the balancer for the tach sensor. Does anyone have any idea on how to wire it so the tach will work? It is a gas tach in a 95 f150. There are 3 wires comming off the sensor, and I would like to do this right. Any help would be appreciated. Thanks!
Look to Dakota Digital. You will need an interface module that will change the crank signal to one you tach can use. They are adjustable so you can dial it in. You'll need a reference tach to get it just right. A handheld laser tach would be the easiest. I believe the model is a DSL-1.
So for the diesel tach, (like an early powerstroke) the computers takes in a 4 pulse signal from the cam or crank sensor, im not sure which. And the computer puts a 58 pulse signal for the diesel tach?
What about using the sensor from the gas engine on a modified mount? Then you will know you have the wiring and the pulse intensity correct for the factory tach. This is the approach I used on a 2003 which has the computer between the sensor and the instrument panel: http://www.4btswaps.com/forum/showth...e-a-4BT-or-6BT
'88 Ford Ranger 4.6 gas, 273k mi. Original owner and paid for 21 yrs ago. Why yes I'm cheap! 2003 Ford Expedition: 4BT with air-to-air intercooler, 3200RPM spring, CPL 858, M5R2 trans, 3.73 gears, 31.8" tires-- mostly done; Daily Driver since Nov 2010.
By far the easiest way will be to buy the Dakota digital dsl-1 box.
It hooks into one of the poles on the alternator and uses that signal to create a tach output. And Its fully adjustable as well. 4 wires to hook up and boom, done.
Its $65 with free shipping on eBay.
Your gas tach is most likely looking for a 4 pulse/revolution signal so your crank sensor idea may work. But those sensors are notorious for going bad so if yours is used and your not positive it is good it may not be good. Also the middle "prong" is the output, so that's where you'd hook your tach wire. But I THINK that you have to supply power and ground to the sensor too. Not 100% sure, but I don't know why else there would be 3 prongs.
I was going to try it this way for my truck but in the end it was a lot less hassle with the Dakota digital box.
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