Speedo not working...ABS light is on..need help!!!

[WhiteNoise9924v]

My speedo isnt working and my abs light is on. I got the scan tool and tryed to acces the abs unit but it wouldnt let me in it. I also replaced the speed sensor in the diff and changed the diff fluid thinking that there was metal build up on the sensor but that didnt work....

Does anyone think the ABS unit could be bad???
Any other ideas?

thanks guys. i have the truck sold and need to get this fixed before i let him take it home

 

[CSnyder]

check the wiring rear of the fuel tank.

 

[WhiteNoise9924v]

ok thanks bud. i got my hands on a abs unit for free also so ill check that first

 

[waldershrek]

Usually if your speedo isn't working it's that rear speed sensor but you already replaced that so I dunno. Your motor isn't running constantly is it?

 

[CSnyder]

Also as a diesel repair shop I can say out of many of those speed sensors Ive replaced I have had a few bad ones out of the box.

 

[LNicholson]

Check the wiring too. Gravel roads beat the heck out of the plastic wire loom and the wires. I ended up routing mine through some fuel hose to give it some real protection.

 

[02HO4X4]

I know if you pull the ABS fuse you speedo nor your mileage counter will work.

 

[scottsjeeprolet]

You can check the sensor with an Ohm meter. When they fail the usually fail open.

 

[waldershrek]

I know if you pull the ABS fuse you speedo nor your mileage counter will work.

Wrong. Mine hasn't been in since I bought the truck and my speedometer and odometer work just fine.

 

[WhiteNoise9924v]

ok guys thanks for all the help!!