Bob Gervais

I know you said you've checked the fuses... but bear with me.

Do your dome lights work? If not, it's fuse #8 that's causing your issues. If your dome lights work, check fuse 18 again.

jdickins87

Dome light works every time the driver or passenger door opens, and manually by turning the head light ****. I went ahead and checked fuses 8 and 18 again. They both tested good, but I have extra fuses in the glove compartment so I replaced them anyway (albeit no. 8's 4 amp fuse got replaced with a 5 amp, as I had no 4's). Still no change.

jdickins87

At a loss...

I swapped the speedometer/odometer/PSOM unit out of a 93 Van, that matched my 94 F150's (aside from a slightly different paint job on the speedometer). Still no working speedometer, or odometer... I'm perplexed.

I found out that the van had 300,000+ miles on it after installing the unit in my F150. Maybe, the van's PSOM had failed as well before they junked it? Looking at the back of the PSOM circuit board I didn't see any thing that looked burnt, or solder points that were disconnected. Of course I didn't see any visible damage to my F150's PSOM when I pulled it either.

Could it still be the speed sensor? The ABS light did go off after installing the correct speed sensor. Could the speed sensor be sending data accurate enough for the ABS' purposes, but not good enough for any type of Speed/Distance calculations? The fact that the ABS light did go off seems to indicate that the old speed sensor was a problem, but was it the only one? Is it still partially a problem?

Any thoughts? I'm hoping I don't have to break into the rear diff. When I pulled the old speed senor there were no metal pieces, or shavings. I would think any damage in there would have latched onto the speed sensor's magnet.

Rusty but trusty

If it was parked for awhile you may have had a furry friend chew some wiring. Time to start looking at the wires. I believe they run along the driver side frame rail

jdickins87

I did notice the new sensor was not properly seated in the rear diff. The placement of the O ring on the new device prevented it from sitting all the way down. By moving the O ring from its grooved position on the sensor up to the base of the bracket, I was able to get it about a quarter inch further into the rear diff.

Now not only is the ABS light off, but the speedometer and odometer now work*. With a caveat: After 30mph the speedometer jumps around about 5mph in either direction (?). Still not sure what to attribute this to (maybe the after market sensor is just crappy?). In any case, at least the transmission is now receiving the signal it needs to shift properly (I'm done tinkering with it).

Incidentally, during the course of this I did find a great app that allows you to use the GPS in your phone as speedometer. It has some nice features and proved quite accurate. You can find it here (for Android): https://play.google.com/store/apps/d...ndroid.digihud

Manuellabour247

I would check that sensor after driving it for a while. I know some of them are a pain to get seated all the way in, but the o-ring should have been left in place. The sensor should slide all the way down with a bit of force. I realize if you don't do it right you may break it, but it beats having oil leaking everywhere and possibly burning something up.

That said, if there's no leaks, carry on. But I'd still check it once in a while to make sure.

fltdriver

The jumping needle at higher speeds is probably from road vibration moving the sensor, I agree with Manuellabour247 about the O-ring being left in the proper position, having it like it is is just asking for more issues.

94fordguy

I had that same problem today after I washed my truck. Fuse 8 was blown. Just wanted to give thanks to you fellas . Now, off to find to find the problem. Hope it was just a coincidence...