I follow the self test to the T and my rear abs light just stays solid. No flashing just stays on. What do u guys think? Truck is 1990 f250

 

Check the wiring connection at the brake master cylinder.

 

it could be a bad RABS unit, or a brake line broke and hte unit was not properly bled.
my RABS has been disconnected since 3 weeks after i bought the truck because ford could not get it to work properly.

 

Is your brake warning light on as well?

 

Nope just the abs light

 

From Steve83:

Flashout Codes

Whenever the yellow REAR ABS light comes on during normal operation, a flashout code may be obtained to aid in problem diagnosis. If the vehicle is shut off before the code is read from a RABS-I module, the code will be lost. In some cases, the code may reappear when the vehicle is restarted.

More information:
RABS Codes

RABS Flow Chart

RABS Troubleshooting

All courtesy of Steve83

 

There are two connections at the master cylinder. The circuit that turns on the red brake warning light is separate from the circuit that turns on the yellow RABS warning light and a connector that is broken internally could cause one or the other to lose connection without affecting the other.

 

The connections are in good shape

 

So what i do is I ground the black and orange wire underneith the driver side dash with a jumper wire going to the frame. I have the parking brake off and running lights on. I then turn on the key. The abs light turns on and stays solid. No flashing.

 

Obtaining the Flashout Code
A flashout code may be obtained only when the yellow REAR ABS light is on. No code will be flashed if the system is OK. There are certain faults (those associated with the fluid level switch or loss of power to the module) that will cause the system to be deactivated and the REAR ABS light to be illuminated, but will not provide a diagnostic flashout code.

Before obtaining the flashout code, drive the vehicle to a level area, and place the shift lever in PARK for automatic transmissions and NEUTRAL for manual transmissions.

Notice whether the red BRAKE light is on or not (for future reference) and then apply the parking brake.

Keep the ignition key in the ON position so that the code will not be lost.

To obtain the flashout code, locate the RABS diagnostic connector (with the Bk/Or wire), and attach a jumper wire to it. Momentarily ground it to the chassis. When the ground is made and then broken, the REAR ABS light should begin to flash.

NOTE: If the red BRAKE light was on (as noticed before the parking brake was applied), the problem may be with the low fluid level circuit and, in this case, no flashout code will be flashed and the light will remain on steadily.

 

Ok. Ill go out there and try it again. Thanks

 

If that does not work, you probably have a bad RABS module.

 

pardon my thread hi jack here but the ABS has never worked on my truck since the day i got it, which was 14 months ago, in the time ive owned my truck the abs has never worked and about 20 minutes ago i was sitting in a drive thru waiting for food, and my (ABS) light started flashing out of no where, it flashed 15 times rapidly and paused for about 2 seconds, wouldnt stop til i turned the truck off then i started the truck back up about 10-20 seconds later (ABS) flashed again i got home, turned off the truck made sure float was at the top, unplugged the little connector on driver side of master cyl/res and started truck back up after 20 seconds the light came back on, i gave up took my food in now im here writing this post, ive read a couple things on this and found out 15 flashes = memory loss... i dont have the slightest clue as to what that means ive tried following the trouble shooting chart steve83 posted and dont quite understand what alls goin on with that, some assistance would be greatly appreciated!
TIA
-85F350IDI

 

what truck are you referring to?

 

My sig truck, the 95 f150 ext. Cab reg. Bed 2wd