1995 Beaver Where does the tach get its signal from.

[Pogoil]

The tachometer.on my motor home is erratic at times. Alternator is working correctly. Cummins 6cta 8.3 mechanical.
Thanks,

Pogoil.

[DonBaja]

If the tach gets jumpy only when the generator is operating I have some understanding of that problem.

[liborko]

Most Class 8 trucks pick tach signal from flywheel teeth (around 112 depending on engine). Erratic tach reading could be caused by poor connections in wiring OR pick-up sensor too far from flywheel teeth. If I remember correctly the proper adjustment is back-off 3/4 turn from contact with flywheel.

[Pogoil]

Thanks for all the replies, I will check this out shortly as I am now nearly crippled from hand polishing my Alcoa wheels.

But they shine like the sun! When your wheels are clean the MH. is clean.

Pogoil.

[babun]

11178adm wrote:
there should be a sensor in the flywheel housing toward the top

Yeap...

[Acampingwewillg]

I think my 96 Vogue with a 3176B Cat gets this reading from a sense wire on the alternator. I have changed out alternators from a Leece-Neville to an aftermarket 200 amp and all is well with the tact.

[MrWizard]

my Safari with Cumins gets the tach signal from the alternator
my tach comes and goes, the problem is in the wiring somewhere

[11178adm]

it's a cummins check on the fuel pump side. if your bed raises for engine access it is easy access, if you have a vom unplug the sensor and check resistance while you wiggle the wires, most sensors have between 1000 to 1800 ohms resistance the reading should be steady while wiggling the wires, if that checks out you could also check the wiring in the rear of the tach, if the wiring checks out and the odometer reads correct but the needle is unstable it probably has a bad tach.

[bluwtr49]

If you go to the Beaver forum we have at least one Cat tech there can answer the question.

[11178adm]

there should be a sensor in the flywheel housing toward the top

[Big_Katuna]

the bear II wrote:
Don't know for a fact but most tachs of that era were getting signal from the coil or distributor. If your engine has a HEI distributor it can affect the tach operation.

It's a Diesel.

[fcooper]

Some motorhomes of that era got the tach signal from the alternator. I just replaced my alternator with a different model ( new one = Delco Remy 28SI) and it has a separate terminal designated for use to drive a tach.

Fred

[the_bear_II]

Don't know for a fact but most tachs of that era were getting signal from the coil or distributor. If your engine has a HEI distributor it can affect the tach operation.