This may be a new one so I'll see what you guys think before sending the car off to the shop.

While driving home today the car's front passenger side brake began to stick or otherwise engage getting progressively worse until I pulled over. With the vehicle in Park and running I get out and hear/see a thud on the tire as if the brake caliper is slamming the pads shut every 2 seconds or so, jiggling wires or otherwise finagling the pedal did nothing but after turning it off and turning it back on again the problem appears to have vanished for now?

I suspect electrical I really hope its not something to do with the ABS computer as I'm sure those are impossible to find and replace.

89' XJS with teves ABS system, accumulator ball and all that fun. All front brake parts new(ish) up to the hose lines.

 

Hi Vancouver

Maybe you have DTV

Disc Thickness Variation, where one side of the Rotor has worn thinner than the other, which causes the Brake Pads to be bounced from one side of the disc to the other, which could be caused by not letting a New Set of Brake Pads properly bed in, or maybe just a Stuck Brake Pad or a Sticking Caliper

On the other hand if your Shop finds there is a problem with the ABS, get back as it could be a very easy fix (in the scheme of things!)

 

Sounds like the actuator is applying pressure to the side/corner. Shouldn't do that of course. Check the surface of the ABS sensor and rotor and clean it.

Then try and see what happens. That is the cheapest start.