robertsdonovan.com

 

How to disable a R56 Mini Cooper brake wear sensor indicator

brake sensor warning lamp and service indicator

Back in November I replaced the brake rotors and pads on all four corners of my ‘08 Mini Cooper. Part of the process involves replacing the wear sensors on the front left and right rear calipers. I ordered new Mini OEM sensors and dutifully replaced them both. BTW the right rear sensor took about as long to replace as all four sets of rotors and pads :-/

During my 1,500 mile drive up from Sarasota, FL to Watertown, NY in March the amber brake warning lamp and service indicator both suddenly starting coming on every time I started the car (as shown above) – with the amber brake warning lamp staying lit all the time. I consulted the manual and discovered that this was the warning indication for the brake wear sensors. Since I had just replaced the brake pads I knew they weren’t worn down that far already and suspected there was something else afoot. Sure enough, a quick visual inspection revealed the wire to the rear wear sensor detached from the sensor block and sticking out behind the rear caliper:

severed rear wear sensor wire

Now, all these sensors are is a loop of wire that runs through a block of high temp material that plugs into the brake pad. The system looks for a break in the current flowing through the simple circuit to indicate that the block has worn down far enough to sever the wire. Apparently it is quite common for these sensors on Minis and BMWs to come loose and fail like this. You can see here where the sensor is supposed to be plugged into the rear brake pad/caliper assembly:

brake wear sensor slot

Since March I have simply been doing my best to ignore the light while I waited for my floor jack and tools to arrive at my new house in NY. That happened three weeks ago but now I’ve decided to trade the Mini in for a 4WD SUV that’s better suited for the winter weather up here. So, I’m not too keen to go through the expense, hassle and bloody knuckles of buying and replacing the broken sensor, but I do want the light to be off when I get my car evaluated for trade-in value. So, I simply jacked up the car, pulled off the rear wheel and connected the two leads together to complete the circuit.

After stripping away the outer insulation I found two small wires:

rear brake wear sensor wires

All I did was strip about 1/2″ of insulation off each wire and twist them together:

splice

Then I folded the extra wire up and and sealed it all with a length of heat shrink tubing:

heat shrink tubing

If you are doing this as a permanent modification (say for a track day car or big brake upgrade) I might suggest cutting the brake wear sensor cable off somewhere on the body and then solder the connection before applying heat shrink tubing to create a more durable modification. Just be sure to cut the replaceable portion of the wear sensor wiring assembly and NOT your main wiring harness! If you find that splicing the wires doesn’t solve the problem (i.e.: the dash warning light doesn’t turn off), be sure to check both sensors and the plugs where the sensors connect to the wiring harness. Also, check the brake fluid level as that can create a similar warning indication (and really IS a problem).

I left mine pretty visible as I wanted it to be noticeable so that the next time the brakes are serviced the mechanic will see what I’ve done and (hopefully) think to replace the wear sensor.

The end result is a gloriously warning-light-free dash. The service indicator is also gone at start-up:

no more warning lights

And just in case anyone is thinking that I have created some kind of safety issue for the next owner of this car, rest assured. The Cooper has a mileage based brake service indicator that will alert the driver in plenty of time before the brakes are warn down too far. In fact, the wear sensors are designed as more of a last warning before the mechanical wear limit indicators built into the pads start squealing (and gouging the rotors). Nobody should let their brakes go that far!

Hopefully this will help me eek out a few extra hundred bucks on my trade-in. Stay tuned to find out what I buy next!

9 Responses to “How to disable a R56 Mini Cooper brake wear sensor indicator”

  1. 1
    Wally Gooch:

    I appreciate the simple fix. I had been having much the same problem with my “09 S. I had changed the rear brakes, well before any sensors told me to, and could not get the reset on the lights. I then replaced the sensor cable and, lo and behold, it came loose and got badly messed up. I know that I replaced that sensor firmly and well enough for it to have remained in place, but I guess they need the money. Two days ago I was on my laptop and decided to check to see if any answer of my problem mentioned. I noticed your site and tried it. It worked very well. No unwarranted service lights any longer. Thank you very much, I appreciate your help. I used to be an electrician, in a different life, and I felt stupid after reading your brief explanation of the issue. Thank you very much. Wally

  2. 2
    Lily:

    Wow this is super helpful. I’m thinking this is the same issue with my Cooper.

    About a week before Christmas, I took my car into a mechanic to have them replace my brakes and rotors and whatnot. I don’t know much about cars but he told me that basically, my brakes were worn down and needed to be replaced ASAP, so I said ok. Christmas Day, I started my car, and the same light immediately came on. Since then the brake light has been permanently on the entire time I’m driving but I know my brakes don’t need replacing.

    I wonder if the mechanic didn’t put the sensor back or perhaps it’s come loose just like yours did. Do you think this warrants a visit to the MINI dealer? Or should I attempt to do this fix myself?

  3. 3
    martin:

    Yes i just have reset my front brake wear warning indicator. On a 2011 mini one. Took off the old sensor (at left side front wheel) at connection behind wheel arch liner, cut sensor cable and soldered both ends together, sealed it off with shrink wrap, plugged it back in, reset instrument as described on various sources on the net. Cannot believe such a simple fix for getting rid of this annoying red warning light.

  4. 4
    Robert:

    I don’t get why the sensors are needed anyway. The maintenance computer tracks wear based on mileage and usage and there are mechanical audible wear indicators in the pads. The electronic sensors are really just a back up for a back up that tend to be the first to fail and require a visit to the dealership to fix. Perhaps that’s the whole point…

  5. 5
    Robert:

    Lily, my guess is the new sensor came loose just like mine did. I would start by taking it back to whomever did the brake work.

  6. 6
    jo:

    FYI – if your brake light is RED you have to change the sensor

    if its yellow, this will work

  7. 7
    Robert:

    Yes, a red BRAKE light means the sensor has been activated (or that the brake fluid is low.) Mine started off red so I replaced the sensors along with the brakes and reset the service odometer to turn the light off. Then one of the sensors came loose and the light came back on yellow, which led to this modification :-)

  8. 8
    LeannQ.:

    I just did my rear brakes in my 2009 mini for the first time. I’m having a heck of a time getting that rear sensor plugged into car! Attached to brake pad just fine. Any tips for getting in plugged into the actual car?! Help…

  9. 9
    Robert:

    I can’t think of any specific tips. It is a bugger for sure. Just make sure you have it in the right orientation and keep at it. I recall spending longer trying to get that damn sensor plugged in than I did servicing the rest of the brake system! This was the primary reason why I chose to disable the sensor indicator when the sensor came off. No way I was going through THAT again :-)

Leave a Reply