Brake Pad - Sensor - Front and Back ?

[rik007]

Hi have the brake pad low warning sign on the dash. I have replaced the discs, pads and front sensor. But still its showing as low pads.

Is there a sensor on the back brakes discs as well? Which side is it? Off side also?

With thanks, Rich.

[SD1too]

Originally Posted by rik007

Is there a sensor on the back brakes discs as well? Off side also?

Yes and yes Rich.

Simon

[madeupname]

Also remember the rear sensor is a smaller shape than the front one

[Jim Jamieson]

Save yourself some money and hassle and remove them. Loop the wires together and plug them back in.

Better to check brake pads physically than rely on unreliable sensors.

I've looped mine on the last 4 or 5 cars I've owned including the XF which displayed the warning with 50% of the pads left.

[rik007]

That .... is a very good idea.

Have to say, these sensors are certainly 'conservative' to say the least.

Cheers, Rich.

[rik007]

Snipped off the lead of the rear wear sensor, wired two lines together. Hey presto light goes out.

QED

Thanks for the help!

[T-Cut]

Originally Posted by rik007

Have to say, these sensors are certainly 'conservative' to say the least.

That was MGR's philosophy for safety sensitive wear. The warning pops on when there's at least a thousand miles more brake use. The idea is to change the pads 'when convenient'. I guess that's better than forgetting to check them till it's too late - which is what many drivers do.

TC

[SD1too]

A regular topic on the forum is "which brake pads (and discs) are the best". Members get quite emotional about this subject. The Mintex brand crops up quite often, as does Pagid. People like cheap Lidl tools but I doubt that there would be many takers for their brake pads, if they offered any for sale. One member recently asked for opinions of Apec pads and I endorsed them from personal experience. I was immediately shot down in flames by a very popular trader who insisted that genuine MGR boxed products were the only choice on grounds of safety. The theme was that your life depends upon reliable, high performance brakes and so there should be no compromise.

In this thread we have members disabling a safety feature because they resent paying for a replacement wear sensor which is not expensive. Furthermore, as has been suggested, if regular visual checks are made of the pad lining, future triggering of the sensor can be avoided whilst leaving it in place "for peace of mind".

These two philosophies don't seem to me to be consistent. I apologise in advance for any offence caused, but deliberately shorting out a brake pad wear sensor is the territory of "bodger man" and this club exists to ensure that his practices do not prevail.

Simon

[rik007]

You are quite correct, the senors are a good idea. Assuming the work correctly.

Which in my case they have not. The wear indicator came on, I looked at the front discs and pads and they looked OK. But as they were part worn I changed them all the same, just to be on the safe side and address the light coming on. However the new pads and discs were, it turns out not needed. Accidentally I pinched the wear indicator lead putting the front system back together. So I bought a new lead and installed that, just to be on the safe side. But that didn't address the light issue either.

Now I admit I was naive as I didn't reckon there being one on the back brakes as well.

However took the back wheel off and hey presto, there was a rear wear sensor. Again the pads and discs looked OK. So I was a little confused. Eventually I tracked the wiring for the sensor and found this was very worn in a couple of places. So I thought right, that's it I'll chop it off and wire it together. Fortunately the wear light went out.

But how do you know I wont be buying a new rear sensor? Well I guess that's not a fair question really. I will be as I have a wife and kids that use the car and use it for towing. Safety these days does come top of the list.

So the tale, really is that brake ware sensors give false positives and can cost you more than a manual inspection. After all most of us managed just fine before the introduction of sensors.

Always reminds of the airliner crash, which spent time dumping fuel before landing because they had nose wheel light showing not 'down and locked'. So made the plane ready for landing. As they approached the runway fuel ran out and it crashed. They had become fixated on the landing gear issue. Turned out that the bulb had failed, giving a false positive.

Rich

[SD1too]

Originally Posted by rik007

So the tale, really is that brake ware sensors give false positives ...

Another way of saying "false positives" is "fail safe". That's what you have experienced:

I tracked the wiring for the sensor and found this was very worn ...

Where would we be without "fail safe" systems? You are doing the right thing Rich by renewing your rear sensor.

Regarding your analogy to the recent aircraft accident (in South America wasn't it), from your description I would judge that the crew's error was in their fuel calculation. They were correct to take the undercarriage warning seriously.

Simon