I have read on here about the speed odometer and abs light coming on to mean the rear differential speed sensor needs to be replaced. But has anyone had the Tachometer and abs light problem.

 

I have a similair problem like this during wet weather I get a hard shift (2->1)and a bouncy tach during braking. I know its a break in the connections somewhere on the Vss line but have been unable to find it. I fixed it for 6 months when i opened all the connections I could find and cleaned and greased them, but now since there was a little spring thaw it came back. So there must of been some water that got in a expanded possibly opening that exposed area back up. So you probaly on need to replace your Vss. Its pretty simple and its located on your rear diff. right on the top. It should only take a few minutes to replace and then reset your truck and hopefully you are fixed.

 

so replacing the rear differential speed sensor should fix the tach problem also

 

my tach problem was when the vss was acting up; the tach would drop about 20km everytime a touched the brake and then take a few seconds to jump back to the correct speed. Once I opened everything up and dried it out everything went back to normal. If you want to know that its your vss for sure; you can ask someone if they have a scan tool and then once hooked up drive around and see if it registering the correct speed. When my was acting up it just showed 0km/hr as my speed on the scan tool even tho I was crusing down the highway at the time and my tach showed 80 km/hr. Hope this helps

 

I checked my haynes manual and the VSS is only on model years 97 and earlier so it must be something else.

 

I replaced the speed sensor in the rear differential but the tach still jumps around any ideas?

 

I am still unable to find what maybe causing this anyone have another idea

 

My guess would be a bad ground or bad connection at the coil which should be where it reads engine speed.

 

Where would i find the bad ground? how is the Tachometer connected to the coil?

 

Bear you have any ideas on this?

 

Purchase a manual. It should have a wiring diagram in it. Sans that, look for any dirty connections in the ingnition system.

The tach determines the engine speed by counting the electrical imppulses from the coil. As yto how it's attached, a wiring diagram would be a big help to you. I don't have an intimate knowledge of the wiring arrangement at the coil. Perhaps somone else here might.

 

If I rev my truck while not moving up to about 5500 my spedo needle jumps up a bit.

 

I have a manual with a wiring diagram to look over I was just looking for a little more insight on this problem or maybe somebody else that has already had this problem. fddriver if the speedometer jumps you make want to look into your rear diff. speed sensor

 

It happens when I'm stopped and I give it a quick rev up to the higher rpms.

 

Hello JJAPHIPPS22,

I too have this present situation on my Ranger & will follow up w/ an update when I resolve same and now that I know of the possibilties will be soon.

And maybe more of us here @ FTE could be of more help to you if you could fill us in on what vehicle you are refering to...or am I missing something.