Ok, so after doing a TON (hours worth) of searching & reading the forums, I think my next step to my problem is to check my exciter/toning ring in the rear differential?

Here is what has been going on:

My dad bought the truck brand new in 98 (1998 F150 4.2L V6 RWD 144k) and we still own it though he now drives an 04 F1 4x4. The reason he bought the 04 was he "no longer felt safe" in the 98 as it constantly felt like it had unreliable braking issues. He said at times the ABS light would come on, IIRC he said around low speeds like in traffic or coming to a stop it would feel like the back brakes would lock up and not engage, causing the truck to keep moving. He has replaced the rear shoes w/ all new hardware, rear drums, bled the brake lines ensuring all air was out, and it still kept doing it.

Now I am trying to get this truck fixed and back on the road so I can drive it and the first thing I thought about changing was the cheap $10 ABS Sensor located on top of the pumpkin. Now, although I'm new to trucks and have never dealt with a rear differential before, I thought it was pretty straight forward. D/C'd the negative battery terminal, Jacked up the truck, Unbolted the 13mm bolt, pulled the sensor out of the diff, unclipped the old one, lubed up the new one's O-ring with some oil, placed the new one in, reclipped the the sensor to the wiring, bolted down, and wah-lah! Thought I was done. Went to test drive the truck in the driveway and noticed my speedometer was no longer working. The first thing I did was pull the new ABS sensor out (which I did notice it had little metal pieces stuck to the magnet) to replace it with the old OEM one to see if the speedometer would come back. No help.

Every other gauge on the instrument cluster works perfect, except for the speedometer/odometer. So, I come back to the forums and read, read, read. Here, I find out everyone is saying that the sensor on the rear diff. is only an ABS sensor, and the VSS (Vehicle speed sensor) located on the transfer case (driver side) of the tranny is what feeds the ECU and then the PSOM the input of the vehicle's speed to tell the speedometer how fast the truck is travelling. So, I run to autozone to pick up the $20 VSS made by Duralast, it was exactly identical to the OEM one I pulled, and so I replaced it. I go to test drive the truck, STILL no spedometer/odometer function.

Third thing I did was check and recheck every single fuse in the fuse panel. and I mean, I pulled each and every one out, double checked the ampages, inspected the fuse itself, and put them back in one by one. (b/c I know that some fuses affect others even if the manual doesn't say they do). Every single fuse is A+ condition, ready to go.

Lastly, I d/c'd the negative terminal of the battery yet again for about 20-30 mins thinking that maybe the system was not recognizing the new sensors and I would "reset" the system. After reconnecting the battery, still no speedometer/odometer function.

Came back to the forums and for the last couple hours have been reading the forums and googling. For what I gained, the rear ABS sensor does in fact affect your speedometer and transmission. As the rear exciter/tone ring spins in the rear diff. the sensor picks up the information through the magnet and sends the information, along with the information from the VSS to your computer/PSOM/etc. So tomorrow I would like to take the rear diff. apart and inspect it. I have no idea if I could have possibly damaged it during the first removal of the old sensor? Or is it possible that the new sensor isn't sitting close enough to the tone ring causing too big of an air gap, thus it is getting a weak signal/no signal at all?


So, sorry for the long and detailed story but I feel when diagnosing all information/what has already been tried and passed should be mentioned. Does it sound like my next step is to inspect the rear diff. exciter/toning ring?

Thanks in advance!

Addendum:
# 3/8 Ratchet, and 1/2 socket
# Brake Cleaner such as Brakleen
# Drain pan
# Small funnel with hose
# Rags/paper towels
# 3 quarts Redline 100% Synthetic 75W90** gear oil (Ford specifies only synthetic!)
# Replacement differential cover gasket
# Gasket type blue silicone sealer
# scraper blade or flat wide chisel
# flat blade screwdriver
Does this sound like all of the required items/tools I would need?

 

Couple of things.
You don't need to tear into the rear to check for a signal from the sensor.
Use a voltmeter on a low AC scale connected to the leads and run the rear on jack stands and look at the output signal.
The system should have a diagnostic port to see codes for the fault.
Do it correct to find the faults and not guess, same as a good shop would do.
ABS is not designed to prevent normal brake operation, only provide a more controlled stop under near panic conditions or low traction road surfaces.
You may have more than one issue causing confusion.
Basicly when the brake pedal is pushed a switch allows the ABS controller to look at the signals from the front and rear.
If there is a large enough difference the controller begins to 'modulate' the brake pressure to the rear to revent lockup.
If the ABS does not work, the rear still works as if no ABS were present.
If the ABS does not work and your sure the rear brakes are not doing their share of the braking, then you have two issues.
Good luck.