Sometimes when I'm driving like when i getting ready to park or when I'm like stopping at a light My brake system on my disco makes a robot sound like it going up then down plus when that happens the ABS light comes on and the brake pedal kinda jolts back and forth hella fast. It doesn't happen all the time. Can someone please tell me what's going on, what should I do and is it gonna cost me big bucks.

Thank You.[8D]

 

Sounds like your ABS is kicking in due to a faulty sensor.

Now before you panic, the fault could be several things, and some don't cost anything to fix.
One is a build up of dirt on the sensor, so a good clean will slove the problem.
Two is the sensor has become dislodged due to brake changes or mud getting into the space. (depends what you have been doing with your disco...)
So simple realignment will solve the problem.
Three is a faulty cable in the system, which could be anywhere and would take some finding.
Four is the failure of the sensor, though I would expect you to have had a warning with the ABS light been lit all the the time.

 

It doesn't light all the time just sometime I will clean the sensor I have been mud running my discovery also I will have a alignment to also solve the prob. or look to see if the ABS computer sensor is faulty.

Thanks

Lighting 90

 

I recently had a sensor on my drivers side front that I suspected was bad, but the ABS light didn't light up 100% of the time After many hours of testing, I figured out that the wire lead to the sensor itself had a partial break in it. When the wheels were turned straight, the sensor would check out fine. When turned to the left or right, the electrical resistance would start to increase until I would get a complete "open" reading on the multimeter.

After careful examination, it looks like the dealer had pulled on the lead during a swivel ball swap-out, causing it to be damaged.

My point would be that you could pretty quickly determine if it is one of the sensors by using a multimeter. The reading should be somewhere between 900 and 1000 ohms (or so).

If you have pulled the sensors out a couple of times, I would also look at the copper bushings to see if they are damaged. They tend to get deformed with repeated sensor adjustments.