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It has the "8" terminal that puts it in 8 cylinder mode if grounded, and 6 cylinder if not. So, his harness not having that lead grounded, it'll be in 6 cylinder mode.
But, not all tachs for the big trucks have that terminal, so it is good to be aware of that.
It has the "8" terminal that puts it in 8 cylinder mode if grounded, and 6 cylinder if not. So, his harness not having that lead grounded, it'll be in 6 cylinder mode.
But, not all tachs for the big trucks have that terminal, so it is good to be aware of that.
Exactly. This is what you don't want if you are looking for a low rpm tach for your six cylinder...
After looking at the chart posted by number dummy and looking at the terminal markings, David and I think the 4500 tach he sent me will work for a gas engine, and the 3500 tach was for some kind of diesel application. I returned the 4500 tach to him and he sent me the 3500 model to try with my 6.9 IDI diesel truck once I get it running. I suspect the signal will be different. There are many 3500 tachs on number dummy's chart and they seem to be transmission specific. This makes me think the signal may indeed come from flywheel teeth. Nevertheless I will play around with it just to see what it does. The IDI counts injection pump gear teeth, 106 teeth = 53 pulses per crankshaft revolution. The 3500 tach is really neat looking. It has more marked increments than the other low rpm tachs, it has a WHITE needle, and a horizontal rectangle under the RPM x 100 text. Very cool to see in person, for everyone else here are pictures
Look at what is currently listed on ebay, Jonathan. It is a NOS one! Note that the NOS one does not have the rectangular marking at the bottom of the face [underneath the RPM X 100]?
Look at what is
currently listed on ebay, Jonathan. It is a NOS one! Note that the NOS one does not have the rectangular marking at the bottom of the face [underneath the RPM X 100]?
Whoa!!! That is a nice find! Too bad the input signal for these is problematic. The last response I got from the medium duty forum is that it came from the alternator.
David, if you look closely the rectangular box under the RPM X100 is there, it is just not painted white. Very odd. Also the needle is orange. On the one you sent me the needle is painted white NOT faded... Also note that on mine the engineering number has a suffix of "DA" and the one for auction has "CC" in ink. There were several different 3500 tachs depending on the vehicle application and which transmission it had.
The farm bought 94 f-series truck the speedo has some different markings at 60.
Tach has the same markings at 2500 and the truck has a 12v cummins with auto trans.
