i have 95 fs bronco 302 5spd manual. today i was wheeling my truck and when i got on the main road my speedo wasnt working did a search of what could be wrong i checked the rear dif sensor thing and sprayed wd40 on the connector checked fuses 8 and 18 and others. what the heck could be wrong? something im missing?

 

ive also read about the rabs sensor but i cant find any info on where it is located or what it looks like

 

The VSS an the RABS sensor are the same thing and located on the rear end.
Does the LCD odometer light up with the mileage when you turn on the key?

 

didnt know they were the same. good to know! lcd does show mileage when driving. i also held down the reset button and turned the key. the speedo moved around and the lcd displayed a code of some sort.

 

 

Sounds like the PSOM and speedometer head and the LCD readout are OK.

You either have and open wire to the rear end sensor, bad sensor (VSS) or the RABS module.
Something also may have gone wrong inside the rear end.

Could still be the PSOM but being bad this way would be very rare.

 

where is this rabs module i searched and searched with no definite answer? do you possibly have a picture? btw subford ive seen your username on several different sites your willingness to help others is greatly appreciated

 

OOPS,
I just realized the you have 4 wheel anti-brake system.
You may have a bad 4wheel Anti-Lock Brake module.
It is located at the LH front corner of engine compartment.
E-10 in the below engine diagram:





/

 

any way to test if that is the issue? the abs light is not on

 

CHECK SPEED INPUT SIGNAL
NOTE:
Only wiring harness end of connector is to be probed.

Connect Rotunda Digital Volt-Ohmmeter 014-00407 or equivalent to Pin 4 (speed in +) and Pin 5 (speed in -).

Does the voltage increase smoothly and continuously from 0 to approximately 3.5 volts as vehicle speed increases from 0 to 48 km/h (0 to 30 mph)?
OR,

If available, a frequency counter may be connected to Pin 4 (Speed in +) and Pin 5 (Speed in -).

Does the displayed frequency of the signal increase smoothly and continuously from 0 to approximately 667 Hz at approximately 48 km/h (30 mph)?
OR,

If neither a voltmeter nor frequency counter is available, vehicle speed control may be used as a good indicator. If it works normally, then the speedometer module is at least receiving a speed input signal and the wiring and sensor can be assumed to be good.

 

which wiring harness? the obd1 port?

 

No not the OBD 1 port test plug.

You could get at it at the plug that plugs into the PSOM C252 or the plug that plugs into the 4WABS module C119 (E10 in diagram above).
It would be the Orange wire with a light blue stripe and the light Green wire with a yellow stripe.

If that test shows no input to the PSOM the only other test would be the wires from the rear end sensor but you would almost have to have a scope to check them.

You say you check the rear end dif sensor. How did you do that?
Did you replace it?
Did you check the wires running from the dif sensor going forward for brakes in it?

 

One other thing you might try is to unplug both plugs at the 4WABS module and jump the wires from the rear end dif sensor to the PSOM at the 4WABS module location.

That would be, short the light green wire with a black stripe 519 to the light Green wire with a yellow stripe 530.
Then short the Red wire with a pink stripe 523 to the Orange wire with a light blue stripe 491.

Then see if the speedometer works as you drive it with no 4WABS.

Note for all of these test except the last one you would need to block up on jack stands the Bronco with its wheels off the ground with it aimed in a safe direction.

 

How to bypass the 4wabs module for troubleshooting - FSB Forums
is that what your talking about?
since i was offroading when i noticed it stopped working i thought i snagged it on branch or something but i looked whereever a likel;y snag would be but i didint find anything

 

Yes that is what I am talking about. That will bypass the 4wabs module and run the speedometer/psom like a F-series truck without abs.