Tach p/n replacement 92 Breakaway 5.9 cummins

11-21-2010, 04:57 PM

Scott and Debbie

Last year when we bought our 92 breakaway our tach did not work.
After changing the Hull sensor p/n 0473-NN1 we purchased from spartan (Dwayne Miller). We found the Tach was Dead!!. The Tach we bought from Spartan came to be the wrong one ( p/n 0403-NN1-006).
The correct replacement tach was a vdo-333962 This is a Programmable tach 85mm with digital hour meter .
This is what I found out.

The 5.9 cummins with an allison at-542 has 159 tooth flywheel. The tach uses the pulses of the flywheel teeth to read our eng/trans combo has 159 per revolution.
The Tach (hall) sensor is mounted on the top of the bellhousing on the (coach) rh side. It has 2 wires to it and is an allthread with a jamnut.
If you change the sensor the new one has gummy stuff on the sensor face. This is to set-up the
sensor. It is screwed in by hand till the gummy stuff just touches the flywheel then hold it in place and tighten the jam nut. note: I checked mine two or three times and still clearanced it a little with the flywheel teeth and it still worked.
It doesn't matter which wire goes to witch in the back but you can verify it if you want.
The new gauge has a wire diagram if you need it and I have the engineering drawing from spartan if anyone needs it.
upfront I had clearance problems with the new bezel attach system so I bought screws from loews and used the old bracket retainer.
The only thing I had to add was another power wire do too a requirement of the new tach to have a constant power from the batt at all times.
You also have to piggy back another wire for the
light the new gauge has.
The Dip switches on the back a set up to your flywheel pulse count I hope to attach the line drawings to this when I get done.
After all is done you have a new Tach and a digital hour meter. Hope this helps.
If I can answer any question or fax anything to anybody I will. Sorry no pictures !!

As I said I hope this helps.
Scotty