instruments with no computer ?

Cummins Conversion & Builds

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instruments with no computer ?

Postby jethro » Thu Jun 04, 2015 11:35 pm

has anyone figured out a fairly simple way to feed a suitable electric signal to a ford diesel tachometer
without resorting to buying a 350$ kit that has the sprocket and pickup coil ?
Will I need an engine computer ? does the tach system go THROUGH the brain box electrically ?
I have noticed that the sprocket/tonewheel has a missing tooth...... I am guessing that the missing tooth
tells the computer what the crankshaft position is for things like advance/retarding....

hate to spend all most 400$ for a working tach......

Since I have a 1-st gen- it doesn't need to know crank position so all it needs is an rpm read.

thought of drilling a small hole in the idler pulley- epoxying in a cobalt magnet- add a solenoid as a pickup
- take the signal and put it through some kind of IC to re-scale the frequency to whatever the tach is expecting
(which I don't know what that is ?????)
(might use 2 opposing magnets to keep balance .....

Any ideas ? Like to use the ford tach that is in the truck now.

Tim
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Re: instruments with no computer ?

Postby ellis93 » Fri Jun 05, 2015 4:08 pm

I can look at some wiring diagrams for you Monday. They'll show me how it feeds the tach.
93 D250 ,5 speed,4.11s,k&n autometer tach pyro trans boost guages,GDS 60mm h1c 14cm,honed 5x10,hplp/reg,1/8 timing,M+H M2 fuel pin, tims cooler tubz
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Re: instruments with no computer ?

Postby jethro » Fri Jun 05, 2015 9:19 pm

Hi Ellis-
Last night I stropped off the huge ford ps/hydroboost plastic tank- but be 1/2 gallon !
Once I got it off I can see a book sized aluminum cased book-sized object which may be the ecm/pcm unit.
It pretty much looks like the pictures I have seen- so I am now thinking that it DID NOT get removed along with the
old 6 liter. This means I have more options now for many of the sensors-

A junk yard down the street has a a scrapped 2004 7.3L. It has the spedo-tach module exposed.
I was thinking that it it was cheap- I could take it apart and see what it has inside- maybe try feeding it
5 volt square waves at different frequencys and see if it responded..... I don't know if the actuator part of the tach
is a didgital powered or an analog type device. If it is an analog - there must be a d-a converter either in the tach
or in the pcm (on the other end of the tach wires. I would think more likely for it to be in the tach. since there would be no need for analog uses for the pickups signal elsewhere in the truck ( I would think).
I would have thought thee might be some web site that explains electrically how there work- but I havnt found one yet.
At least any with specifics....

I will check the junk yard tomorrow.

Tim
PS I love your animation- do you remember where you found it ?
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