Can anyone explain to me how these tach sensors go bad?

[1994Diesel]

Mine has been going out slowly for quite awhile and i think it has now begun to affect the transmission, only on take off though because idle is the only rpm range that it has trouble picking up.

I have cleaned it before and it didn't seem to do much.

How do these tachometer sensors fail? They must be more complex than im imagining becuase i thought all they were was a magnet

I took the hit and bought one today at the Ford dealership.

 

[GenLightening]

The magnet is only part of it. It also has windings in it that, when the magnet gets excited by the cam gear teeth, conduct the small charge that's produced. Those windings are probably what get fatigued whith the vibrations from the diesel engine.

And if you check the Uhaul post I started, they have the sender for about $46 through today.

 

[icanfixall]

Vibration causes them to start leaking oil thru rhe cap thats crimped around the top electrical fitting. The bottom can be cleaned off and rtv aplied around the edges so no oil can get into the switch. Sometimes the vibration actually causes the wires to break... Thats why a spare under the seat will get you home safely.... uhaulparts.com has these senders for $48.63 after a 20% discount. They list them for $60.79... Even at that price its way below what ford charges.... Sorry...

 

[1994Diesel]

Well thanks guys, my curiosity is appeased

I searched for the part number(17B384) on the Uhauls ebay page and i got no results?

Maybe they sold out all ready.

Even at that price its way below what ford charges.... Sorry...

Its no big deal, im sure i could return the ford part if i had to...

 

[OLDBULL8]

Take a hacksaw and cut it in half, see what's inside. It operates on the Hall effect, pass a coil over a magnet and it generates a voltage. Not teaching electronics just now but that is the general consensus.

 

[GenLightening]

Well thanks guys, my curiosity is appeased

I searched for the part number(17B384) on the Uhauls ebay page and i got no results?

Maybe they sold out all ready.



Its no big deal, im sure i could return the ford part if i had to...

Try E5TZ17B384A

 

[1994Diesel]

Ha! found it!

Im going to attempt to return the tach sensor tomorrow before i buy one online though.

Thanks a bunch

 

[1994Diesel]

They're having a 20% sale through Jan 31

Right. I forgot to read that part.

Im going to attempt to return the tach sensor tomorrow before i buy one online though.

duh, i guess i have to order it tonight.

 

[yARIC008]

From my experience, they seem to go bad where the wires connect to them. If you get out and wiggle them the tach will go on and off. And eventually it just doesn't wiggle on and off anymore because I assume the wires have fully separated due to vibration and what not.

 

[yARIC008]

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mistake post.