Hi, my truck is a 1994 302 2wd super cab.
The have the ABS warning light on for a couple weeks now (no CEL), so yesterday I pull the codes and get 536, Brake on/off Circuit Failure on both KOER and KOEO test. Is this the reason for the ABS light to be on?
Or maybe because I change the brake bulbs to leds?

 

Brake pedal not depressed and released during the KOER Self-Test.
Brake pedal depressed during entire KOER Self-Test.
Open BOO/stop lamp circuit.
Short to GROUND or POWER.
Damaged brake switch.
Damaged Powertrain Control Module (PCM)

If you think it's the bulbs change back to see if that fixes the problem. Also some LEDs have to have a resistor wired into the circuit to make them work right.

 

Low brakes possibly, happened on my ranger, put new brakes on and light went out.

 

Same thing happened to me this week. The ABS valve (in my case RABS valve) has an internal needle piston that normally rests TDC between two switches. These switches activate the light if the needle piston contacts either switches. This can occur at the end of the pads life as the travel increases as a result of the wear.

 

Here´s a new clue, when I use the turn ligths the ABS turns off.

 

So is this kinda like "clue"?

 

Reading the engine computer doesn't read ABS codes, you have to read the ABS computer. Is only the ABS light on or is the brake light on too?

 

Only the ABS light.
How can I read the ABS computer codes?

 

Only the ABS light on definitely means an ABS problem. I don't remember how to get those codes but it has been posted a few times elsewhere. You can try searching or wait for someone else.

 

See Link: http://www.fullsizebronco.com/forum/...d.php?t=180453

Don't confuse your ABS test connector w/ your OBD1 test connector. On my 87', my RABS test connector in in the cab.