Abs & brake lights come off & on ,Code read open right sensor . Replaced Rt. frt wheel hub & sensor . Still got same code , Put ohm meter on wires up to fuse box & found no breaks in wires . I replaced the rear sensor a year ago , also noticed speedometer on the take off sometimes does not work until I get going for a ways . Also the right head light is very dim, replaced the bulb , same, replaced head light switch , same , put in a different dimmer switch , no change , then I checked all the grounds , loosened & retightened , no change .My truck has single head lights & fog lamps, no daytime runin lamps . Truck is a 1999 , 3500 ,diesel , But rearend is a 1994

 

I know the '98.5 truck's speedo reads off of both the tranny (or transfer case if 4wd) and the rear end.
Can't remember which way it goes but one sensor reads for under 30 mph, the other for faster.
Could be since you have a '94 rear end the sensors aren't communicating with each other correctly.

 

Thankx for the imfo Infidel, I'll check out the sensors , have a good one !

 

A partially blown fuse can cause the headlight problem.

The rear diff speedo sensor reads (if I remember right) the teeth on the ring dear of the differential like a reluctor. Above x mph (I thought it was 15mph) it reads the transmission sensor. I'd take another look at the rear diff wiring. Some cheepo scanners goof on which sensor is iffy, or the computer may get different readings and point the finger at the good sensor instead of the bad sensor.

I don't *think* the front wheel sensors affect the speedo at all, but the computer compares the various sensors to operate and verify function of the abs system. It might have goofed identifying the RF sensor.

 

Is your right front hub going bad?
Is the replacement sensor in the right front hub at the proper depth to read off of the reluctor ring inside of the hub?