Firstly, check what the fault is! Dont fix a brake corner that doesnt need fixing. You might look for physical damage (like a broken ABS line), use diagnostics (eg Nanocom which will tell you whats wrong and where) or test the vehicle (eg DSF wheel only locks despite ABS).
Jack the D2 and use axle stands. Ensure you're in Park and the Handbrake is on.
My issue specifically was an unclipped ABS line had become chaffed on the tyre or rim. It wore through the wire and the SLABS logged a permanent fault. 3 Amigos.
Take the caliper off. Undo the two small 10 or 12mm bolts. Hang the caliper on the radius arm so it doesnt pull on the brake hose. Arrange the pads so they go back in the same way they came out. Bolts back into where they came out of (my tip so I dont finish with spare bolts). Check your pads for wear while you're there.
Next, the caliper mount comes off. Dont be fooled, they're not some fancy back the front torx bolts that hold it on, they're just a 19mm multihex bolts x2 - your ring spanner will fit. These can be tight, so you sometimes need to apply a breaker bar to get these off, or rattle them. I put the bolts into the caliper mount and hung them on the radius arm also.
Next, the rotor comes off. You can tap and smack these all you like (only with a rubber mallet), but unless that little screw between 2 of the wheel studs is out, the rotors going nowhere! Undo the screw, then pull the rotor off the hub. You may need to tap it around to get it to budge.
You'll see the ABS sensor at the top of the hub assembly. 5mm Allen key will remove this from the hub assembly. You dont specifically have to remove this right now.
This is as far as the sensor lead will pull through, thats all of it aside from the plug. I don't think you will pull the plug through.
On the back of the hub, there are 4 bolts that need to be undone to move the bearing block away to provide clearance to pull the plug through. Undo these by about 5mm. I needed 2ft of breaker bar to undo them, so they're tight. If you can rattle them then it may be easier. Tap the bolt heads lightly to ease the fitted bearing block out. Only tap it out far enough to pass the plug through the gap otherwise you may drop the axle out of the diff.
Replace the lead once its out. The ABS sensor has a rubber O-ring. To lubricate this while installing the new ABS sensor, just use a very small amount of dishwashing liquid. I prefer not to use oils in case the rubber breaks down. Reassemble and clip the ABS line back in place at the hub so it doesn't rub the CV joint, along the hydraulic brake line, at the mount and at the bodywork. Check nothing pulls at steering lock and hopefully at full suspension travel.
Put the wheels on and test drive. The 3 Amigos should become the 1 Amigo if all is correctly working. When you reach about 7km/h the SLABS will do a diagnostic and all brake lights on the dash should go out.
