I would like to use the stock 98 dodge tach but from what i found
#1 blk lt blue ground
#2 vio white 5 volt supply
#3 gry blk tach feed


but I don't have those color wires it is a 98 12v I know I can use the cam sensor from the ford but I wanted to keep this part stock if possible

 

I think what you are running into is the same thing I ran into on a friend's show truck. He took a 92 Dakota with a blow V6 and stuck a 2000 Durango 5.9L V8 and transmission in it. We ended up having to get the BCM and what Chrysler calls the central timer module along with the CCD bus from the Durango in order to get the engine to even run. Chrysler uses the CCD bus to link all the modules and the power for it comes from either the central timer module or the BCM. Chrysler clusters use this system to transmit data to the cluster. The CCD bus is a 5 volt twisted pair very similar to the system Ford uses called the SCP or Multiplex Communication network. I don't know if you could use that, but it is also a 5 volt system. The other option would be to get a 5 volt regulated power supply that can be powered with 12 volts.

 

I have coming off sensor
blk
red
grn

I am thinking to hook up
blk = grd
red=12v
green= tach sense

if it doesnt work then I will have to mount the cam sensor off the ford

 

I used the DCS set-up. It uses two wires, one goes to ground, one to signal. I think one could use to stock one if you determine which wire is what. The sensor is a simple pulse generator. I would use a meter to see what the resistance of each wire. I havent tested one, but two wires may be for the sensing portion and one may be a ground. Test the wires to see if they have continuity to each other or the housing.

 

I wired in stock ford with stock 94 dodge cam sensor, put
In two extra notches on dampened. Then jumpered the grn cam wire to pin 19 outside of the PCM on my 99 f250. Works great saved money not needing crank kit.

 

Not to derail the original question but what was the original motor that your tach was reading off of? 7.3 powerstroke? I'm replacing the powerstroke in my 97 with a 24v and am trying to figure out how many notches per rotation are needed.

 

What I found out helping someone use an older (1992) trans controller on a carbureted gas engine was that tach read off the injection pump and had 105 teeth per 2 crank revolutions. If the crank sensor on the powerstroke is 4 pins then a sensor that can read the 4 slots in the Cummins balancer should work. It's bound to be easier than a GM one, they read off the alternator.

 

there is some where in a forum either here diesel bombers or 4bt that tells what year and how many pulses you need


if my memory is correct 94-02 uses 4 pulses after that its like 168 or some god awful number

I used cam sensor off a 99 v10 the most important thing is the spacing between the wheel and sensor .018 is engraved in my brain

 

Cool thanks! I was trying to count the spaces on the tone ring on the cam, where it looses me is how the count is different with its spaces between one half of the tone ring to the other so it's harder than just dividing the number by two to get the correct count to go on the balancer, but even then 4 is surprising as I would have guessed 12 pulses and one missing tooth by what the tone ring usually submits. Thanks for the input!

 

FWIW, a V8 gas engine produces 4 ignition pulses per revolution. At worst case, you could stick a V8 tach in it and a pickup that will give you 4 pulses. The early Dodge/Cummins didn't have a tach.

 

My 99 7.3 required 4 notches for the tach. However the timing gear the cam position sensor reads has I believe 26 notches.

When I hooked up initially my rpm was reading at 200 rpm instead of 750. This was because the signal went through the PCM to the tach. I jumpered the signal wire from pcm to the tach wire all at the PCM connector.
A 24v should have a factory tone ring already, not sure how many pulses it has or how many the obs trucks need.