Dear Users,
I drive a 1995 F-150 SuperCab 4x4 Long Bed with the wonderful 351 Windsor. Recently I noticed my speedometer needle bouncing and ABS engaging at normal, non slippery, stops.
I jumped to the rear axle and pulled out the VSS only to notice it and the magnetic fill plug on my Ford 8.8 LS differential covered in larger metal flakes.
I removed the differential cover and discovered the spider gears had stripped out almost entirely. Needless to say I took it apart, discovered that the left clutch pack ears were completely smoothed out, and replaced the spider gears, clutch packs, and shims. Next I refilled it with 80w90 and 4 oz of Friction Modifier.
To finish up, I removed the fill plug to clean off the metal every day for about 4 days after the repair and finally the only flakes I see are like silver paint on my fingers.
However, my speedometer needle still bounces, mainly staying at 0MPH, the ABS light is lit, the Transmission often goes into LIMP mode with hard shifting at high points, and the Odometer does not accumulate miles.
What should be my text step in diagnosing the issue?

Eagerly,
-Mahoney

 

i just redone the same thing in my 95 rear diff,I noticed the rear sensor was damaged around the tip,and had very small cracks,if magnet is sending a messed up signal,it will affect dash and erratic readings,I hope this helps

 

Thank you,
I have already replaced the sensor twice to rule it out. The readings on it also are correct. I have unplugged the ABS module to double check its function and now the only component left is the PSOM.
I would like to keep my mileage but if I cannot it will be fine.

 

Can you define that statement above? What readings were correct?


That is a good idea to eliminate the RABS controller, it has been known to drag down the VSS signal that goes to the PSOM.

 

Dear rla2005,
The Differential VSS sensor read the correct ohm readings but I cannot remember their value offhand.
I then switched my PSOM module for a known working module and the problem persisted. Finally, I made an appointment with Bloomington IN Ford/Lincoln dealership to provide a definite solution if I could not discover the root issue. I will be taking the truck to Mobile AL in early June.

With this appointment to cure my anxieties and holding my ancient multi meter I set about to work on the proper diagnostic approach. I used a 20' extension cord to test for continuity between the under-hood RABS DataLink (two pin round plug on driver's side fender by EEC IV diagnostic port), and the wiring to the RABS Module behind the glovebox. Both the Red/Pink and Black/Green Wires showed continuity. Next I checked for Continuity between the RABS Module wiring and the VSS plug on the rear differential. The Black/Green wire showed continuity but the Red/Pink wire did not.
The next morning I purchased 10' of Red/Pink wire from my workplace (I work as a Marine Technician) and ran a new wire from the VSS connector to the RABS DataLink using heat shrink splices and tucking the new wire into the loom. The solution worked perfectly! I still have the classic 1-5 mph needle wobble at high speed though.

I was able to cancel that costly Dealership appointment.
I hope this post can help solve the same problems in the future.
-MAHONEY