M35a3 tach not working, need help.

[Dustyh]

The tach in our M35A3 is not working. When you turn on the master switch it will jump but will not work with increase in rpms, all other gauges work. I have read on here that the tach sensor maybe the problem. Could someone advise me as to where the sensor is located and were I can find another one to replace it with.

Thanks, Dusty

 

[WillWagner]

Never dealt with an A3, but if is like any other truck, the P/U is in the flywheel housing. Look for a long threaded deal with two or four wires coming out the top. It will be off center from the top or the bottom of the housing. Try adjusting it first. With the engine OFF, loosen the jamb nut, turn the sender in 'till it touches the flywheel, then back it out 1/2 turn. Lock the jamb nut. BE CARFUL, the sender is aluminum. If you over tighten the nut, you will pull the sender apart. It is best to turn the nut 'till it touches the flywheel housing then give it a slight turn just to snug it up.