Reset Brake Pads Worn Msg After Changing Pads
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The workshop manual advises that the brake pad wear warning indicator sensors must be replaced each time the brake pads are serviced as they wear during operation.
The sensors are little plastic slugs with a thin wire running through them that creates a complete circuit that is monitored by the central junction box to detect if either of the two sensors (rear RH, front LH) wear through the wire through contact with the brake disc/rotor and break the circuit. That is used instead of the method of shorting to ground because it is easy to rule out false-positive triggers, and it is fail safe in that any error in the system will report a warning. If you had a warning before you changed the pads then one or both of the sensors are shot. If you are certain they are ok (a quick resistance test across the sensor wires will tell you that) then check the harness connectors are seated properly and are not caked up with brake dust.
The sensors are little plastic slugs with a thin wire running through them that creates a complete circuit that is monitored by the central junction box to detect if either of the two sensors (rear RH, front LH) wear through the wire through contact with the brake disc/rotor and break the circuit. That is used instead of the method of shorting to ground because it is easy to rule out false-positive triggers, and it is fail safe in that any error in the system will report a warning. If you had a warning before you changed the pads then one or both of the sensors are shot. If you are certain they are ok (a quick resistance test across the sensor wires will tell you that) then check the harness connectors are seated properly and are not caked up with brake dust.
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NateLWB XJ (04-18-2016)
#3
xdave:
Thank you, I'm going to go on a limb and say it's the sensor. I figured I should have just replaced it.
The light was on prior to me changing the pads. I just did the rears and they were definitely low. I knew they needed changing due to the amount of brake dust even before the sensor told me.
Replaced the pads didn't replace the sensor. So you're saying the light should go off automatically if the sensor is good? There's no reset procedure?
Thank you, I'm going to go on a limb and say it's the sensor. I figured I should have just replaced it.
The light was on prior to me changing the pads. I just did the rears and they were definitely low. I knew they needed changing due to the amount of brake dust even before the sensor told me.
Replaced the pads didn't replace the sensor. So you're saying the light should go off automatically if the sensor is good? There's no reset procedure?
The following 2 users liked this post by derrickonline:
Barry Leftwich (02-05-2021),
NateLWB XJ (04-18-2016)
#4
I've not changed the pads on my X351 yet, only the older model which didn't have sensors. However the workshop manual on TOPIx does not mention any reset proceedure. I suspect it is the rear sensor. If you carefully remove it and look at the wearing end I bet you'll see two little copper dots where the wire has worn through, or at the very least exposed copper indicating the resistance has likely increased.
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NateLWB XJ (04-18-2016)
#5
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NateLWB XJ (04-18-2016)
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JagGate, nope. I have done a complete brake job on my car with no special computer and have even gotten a warning light. The trick with the maintenance mode is getting the car to the point that it will re-learn where to put the parking brake when you pull the lever. There are 3 options to this:
1) attach the Jaguar specific computer to put the parking brake computer in maintenance mode so it will relearn things once you tell it you are done,
2) disconnect the battery and then reconnect it so the computer looses what it knows about the parking brake and forces it to relearn, or
3) when doing the rear pads, install everything, but before installing the tires/rims, manually operate the e-brake lever the full stroke length until the pads start engaging the rotor. At this point, things are close enough that the car will not know the difference and not give you an error code.
If you want to do a brake job on your car, come on down. We can do it right in my driveway. Take us about 60-90 minutes an end on your car.
1) attach the Jaguar specific computer to put the parking brake computer in maintenance mode so it will relearn things once you tell it you are done,
2) disconnect the battery and then reconnect it so the computer looses what it knows about the parking brake and forces it to relearn, or
3) when doing the rear pads, install everything, but before installing the tires/rims, manually operate the e-brake lever the full stroke length until the pads start engaging the rotor. At this point, things are close enough that the car will not know the difference and not give you an error code.
If you want to do a brake job on your car, come on down. We can do it right in my driveway. Take us about 60-90 minutes an end on your car.
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Yes nothing special on my 2014 XJR. Did all 4 wheels going with Porterfield CF/Kevlar pads.
I did them early as I learned on the list that if the light goes on the sensor needs replaced. Not a big deal but I wanted to reduce the brake dust anyway.
Need to repaint the red calipers as the cosmetic outer covers seem to scratch the hell out of things!
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I did them early as I learned on the list that if the light goes on the sensor needs replaced. Not a big deal but I wanted to reduce the brake dust anyway.
Need to repaint the red calipers as the cosmetic outer covers seem to scratch the hell out of things!
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#15
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