Brake pads, sensors and other stuff

[oldie]

Recently bought MG ZT-T SE, brake pad wear light has come on (!).

What thickness should the pads be before they require changing please?

If it's the wear sensor can that be replaced independently of the pads, or should they be changed together?

How difficult to replace just the sensor, I think the pads will probably require greater expertise and facilities than I possess.

Any recommendations for technicians in the South-East of England?

Also, it feels to me as though it idles somewhat rapidly (approx 1200) is that standard? It's a while since I have owned a v6 so it may be an inappropriate comparison with my v8 and a couple of intervening diesels. It settles down ok to around 800 quite quickly. But it does lead to the auto box engaging a little fiercely and the necessity to be on the brakes all the time. All-in-all having a bit of a problem feeling the love, although it does drive nicely.

[Lagetha]

I think the sensor receives it's signal when wires embedded in the pad friction material touch the disc, completing the circuit and lighting the warning lamp... Replace the pads!

Sent from my Note_7P using Tapatalk

[vitesse]

As previous, the friction material must be very low before the brake warning sensor is activated, but it could also be a broken circuit - a visual inspection is necessary. You can replace the warning sensor if there's still plenty of material on the pads.

Idle for a V6 is +/- 750, could be time for a replacement idle kit: MKG 100260 (L)
or adjustment of the stepper motor but you'll have to find someone with a T4. There's a wizard working at Souls of Olney (Phil) - well worth the trip.

Regards

[SD1too]

Originally Posted by oldie

... brake pad wear light has come on (!).
What thickness should the pads be before they require changing please?

The official answer to that David is when the warning light has illuminated but this can also happen because the sensor cable has popped out of its bracket, contacted the tyre when on full lock, and the subsequent damage to the wiring then illuminates the warning light, not worn pads. That's the first thing to have checked if you're taking your car to a garage.

Originally Posted by oldie

If it's the wear sensor can that be replaced independently of the pads, or should they be changed together?

If the sensor has been damaged by something other than brake pad wear then yes, it can be renewed independently.

Originally Posted by oldie

How difficult to replace just the sensor ...

It's not difficult at all.

Originally Posted by oldie

Also, it feels to me as though it idles somewhat rapidly (approx 1200) is that standard?

No it's not standard, there's a problem there.

Originally Posted by Lagetha

I think the sensor receives it's signal when wires embedded in the pad friction material touch the disc, completing the circuit and lighting the warning lamp...

To explain this circuit, the sensor tip is effectively a loop of wire encased in plastic. Contact with the disc erodes this plastic covering and the loop of wire, and therefore its electrical circuit, is eventually broken. It doesn't complete a circuit to earth via the disc surface. The front and rear sensors are wired in series so a breakage at either will trigger the instrument pack's electronics to illuminate the pad wear warning light.

Simon

[Arctic]

Originally Posted by oldie

Recently bought MG ZT-T SE, brake pad wear light has come on (!).

What thickness should the pads be before they require changing please?

ss.

Any recommendations for technicians in the South-East of England?

Also, it feels to me as though it idles somewhat rapidly (approx 1200) is that standard? It's a while since I have owned a v6 so it may be an inappropriate comparison with my v8 and a couple of intervening diesels. It settles down ok to around 800 quite quickly. But it does lead to the auto box engaging a little fiercely and the necessity to be on the brakes all the time. All-in-all having a bit of a problem feeling the love, although it does drive nicely.

Hi
It is about a 20 minute job to replace the wear pad sensor, you will know what the pads look like once you have the wheel off.

Jack the driver side wheel up, just a little so the tyre is still touching the floor, undo the studs 17mm so they are loose.
1

Then jack up further so you can remove the studs & wheel.
2

Then from inside the engine bay again driver side, look into the inner wing area you will see two connectors one is blue (ABS) the other black wear pad sensor.
3

Pop this wear pad sensor out of the holding clip.
4

You then look for the two sensor wires with rubber bungs attached in the wheel arch liner.
5

You need to pull out the right bung for the wear pad sensor, in the photo i have removed both has i was doing a different job.
6

You can now press in the top the tang on the black wear pads senor, pull & it will come apart.
7

8

You now trace the wire back to the caliper which you will find the other end of the sensor clips into.
9

10

Sensor clipped into the caliper
11

Pull this out making sure you get the spring clip with it.
12

Connect up the new sensor wiring and refit is the reversal of the above.

Change the pads if they need changing.

[Lagetha]

Originally Posted by SD1too

To explain this circuit, the sensor tip is effectively a loop of wire encased in plastic. Contact with the disc erodes this plastic covering and the loop of wire, and therefore its electrical circuit, is eventually broken. It doesn't complete a circuit to earth via the disc surface. The front and rear sensors are wired in series so a breakage at either will trigger the instrument pack's electronics to illuminate the pad wear warning light.

Simon

I stand corrected

[SD1too]

Originally Posted by Lagetha

I stand corrected

Hi Kevin,

I didn't mean to "correct" you, I hope that you're not offended. What you described is indeed how the sensor circuit on my SD1 worked but with the adoption of microelectronics we now have a slightly different circuit.

All the best,

Simon

[KWIL]

As I read it, OP said the V6 idles at 1200 and then "it settles down ok to around 800 quite quickly."

As normal I would say

[oldie]

Originally Posted by Arctic

Hi
It is about a 20 minute job to replace the wear pad sensor, you will know what the pads look like once you have the wheel off.

Connect up the new sensor wiring and refit is the reversal of the above.

Change the pads if they need changing.

Thank you Arctic, your breakdowns are an inspiring resource.

[oldie]

Originally Posted by KWIL

As I read it, OP said the V6 idles at 1200 and then "it settles down ok to around 800 quite quickly."

As normal I would say

Thank you KWIL. Good to know. The biggest bugbear (and feeling hazardous) is:

". . . it does lead to the auto box engaging a little fiercely and the necessity to be on the brakes all the time. All-in-all having a bit of a problem feeling the love, although it does drive nicely . . ."


All my other automatics have been content to sit-in a restrained manner when at a halt with the gearbox in "D". I'm having to fight this one, it's not a comfortable sensation.