THIS ONE AINT SO EASY, OK I HAVE AN 87 F150 2WD. THE ABS AND BRAKE LIGHT ARE ALLWAYS ON. ALSO WHEN BRAKING ,PEDAL PULSES AND AND TRUCK VIBRATES SLIGHTLY WHEN SLOWING FROM HIGHWAY SPEEDS...FOLLOWING WAS DONE ALREADY..
NEW FRONT ROTORS, CALIPERS , PADS ,SHIMS. I HAVE CHECKED WHEEL BEARINGS AND THERE OK.. REARS WERE ALSO DONE BRAND NEW DRUMS , WHEEL CYLINDERS, SHOES ,RETURN SPRINGS. COULD A FAULTY ABS MODULE OR MASTER CAUSE THIS TO HAPPEN ? ALL RESPONDS WILL BE ANSWERED.. THANKS

 

Sources of brake pulses are improper caliper installation and uneven disk surface or drum surface, you mentioned yours are all new so obvioiusly that isn't it. The warning light could be traced to a defective module or pressure differental valve. It is pretty common for the pressure differential valves to go bad from what I have been told. Let us know if you figure it out, Later

 

one of my friends told me, sometimes it comes on because when someone replaced the pads in the drums on the back they didn't adjust up the pads in the drums.

 

And i'll mention the thing i always doo.

The ABS controll unit in the rear needs to be cleaned out.

 

Please don't post in all caps, it takes longer to read it.

You need to work on the problems indicated by the red brake light first, it indicates mechanical or hydraulic problems and it may be dangersous to drive the truck.

Just because all of the work has been done it doesn't mean that the work was done right, people make mistakes, some new parts are defective.

You mentioned a vibration, do you feel it through the steering wheel or through your seat? this may indicate whether the problem is in the front or in the rear.

 

i feel the vibration through the seat, there is no shake or shimmy in the steering wheel, you can acutually feel the truck shake in the rear....fisrt thing i will do is check the ciontrol moduke for the abs...i take it from there thanks for all the replies..

 

yea, controll module, like allfords said, tahts what i ment. lol.

I gotta find that stupid thing myself.

 

I have the same problem on my 88 F150 and am interested in the outcome. Please keep us up to date on this.

thanks,
Mike

 

Isn't the controll module in the center of the read axle?

I think it's just a little box or something you can pull off and clean out. I'm just going by what i bearly remember my dad telling me to do before he left to go hunting. Cause i need to fix mine too.

 

i havent had a chance to work on the brakes cause my fuel pump went on friday night ....really pissed me off to cause i got stuck in middletown nj and i live a nearly 100 miles from there. but i hope to work on them next weekend...god willing nothing else goes on the truck...hey i shouldnt really complain. i have 252,000 miles on this truck..org engine, org trans...runs like a champ too.)