Park Brake Actuator and Actuation Module for Discovery 3/4 and Range Rover Sport
A common fault on these vehicles is that the electronically operated park brake actuation module starts to screech very loudly.
These vehicles have a switch on the console that controls an electronic module under the rear of the vehicle, which then pulls cables to actuate the actual braking mechanisms on the back wheels. Each back wheel has a disc brake with a brake caliper and pads for normal stopping. However, the brake disc has a little brake drum inside it, and inside this space there are a set of drum brake shoes and adjuster. It is these shoes that are pulled on by the park brake.
If the shoes wear out (for instance by being driven with the park brake still partially on), or if an unskilled brake mechanic or customer doing DIY work fools around with the mechanism, it can become maladjusted. This is one cause of a very loud, rhythmic screeching from the rear of the car when the driver applies the park brake or tries to take it off.
Firstly, it is important to have rear brakes only touched by someone who knows about these vehicles – a dealer or specialist mechanic.
Secondly, the first thing that some mechanics do to fix this problem is to get you to buy a new brake actuator and have it installed. The brake actuator is worth a small fortune – installed, the job will come to around $3000. It takes about 5 hours of diligent wrestling to put one in. The brake shoes assembly must be adjusted to the manufacturer’s specifications (which is crucial to get right), sometimes brake shoes need to be changed.
However – do not be rushing to have a $3000 actuator job done because your favourite mechanic says that’s what will fix it. It can often be adjusted and made to work again.
Firstly, if you have the brake jammed on – here’s some hints on how to release it manually. There’s a little loop of braided steel wire under the console you’ll need to pull on.
http://www.l2sfbc.com/rmp/blog/D3-D3-park-brake-problem-release
Secondly – just don’t use the park brake. Put a piece of electrical tape over it to remind yourself not to touch it. Of course, avoid parking on hills without using the park brake and make sure the car is firmly in park.
Thirdly, book in and bring the car to us. We will either adjust the mechanism and fix the noise, attempt to reepair the actuator, or replace it with a new one.