Incessant Brake wear warning chime

[codemonkey]

I have a 2005 LR3 that I bought a few months ago with 33k miles on it - now has about 35k or so. Once last week I heard a chime and the little info display said "check brake pads". The orange "brake" warning light didn't come on. The warning went away, chime didn't repeat.

I checked all the pads as well as I could with a flashlight, all look like they have quite a bit of wear left, so I figured I'd let it go. Well today I got the same chime and info message, plus the orange "brake" warning light - over and over and over and over....I actually turned around from the all-day trip I had just started and had to get my SLK for the day (the horror!).

Anyway, I just got home from my day trip and re-checked the pads as well as you can without pulling wheels off - everything looks to have quite a bit of pad left. Has anyone had this warning go off falsely?

Also, does it typically chime every 30 seconds or so for the entire time you're driving the car? I've owned other cars with pad warning systems (Porsche, Audi) and never had such an annoying repeating chime for pad wear.

 

[richpike]

Total guess (I haven't had a similar issue), but it may be that they are just getting down to the sensor - the sensor is starting to wear through and it is causing the warning to pop up infrequently. Or, since it sounds like there is plenty of pad, it could be the sensor is bad (just in general).

-Rich

 

[mustbeaudi]

Got a front sensor I bought new for $17-18 and did not need, will mail USPS to you for $17 flat.

 

[codemonkey]

Ok, so the sensor is "consumable" - it wears with the pad, and must be replaced? Rich, I guess that idea makes sense. Maybe I'll do some hard stops tomorrow morning to see if I can get it to burn through.

mustbeaudi, thanks for the offer, I'll need to sort this out and see how I want to proceed. I've done brakes on many vehicles in the past, but my time is a premium these days so it may end up going to a shop.

 

[richpike]

Yep - the sensor is a consumable. I believe there are two of them - one on the front, one on the rear. I forget which sides they are on. If you catch your brakes early enough you don't have to replace them - ours were down to about 10% in the rear and the sensor still hadn't gone off yet. We went ahead and had the rears replaced (this was ~30k miles). Interestingly, the fronts still had plenty of pad left. The brakes had never been changed - I thought it was interesting that the rears wore faster than the fronts. It is usually the exact opposite (the fronts do the majority of the braking) - I have a feeling LR tuned the brakes to be rear biased unless you apply a certain amount of pressure. Pretty smart - it helps the pads wear more evenly.

-Rich

 

[Houm_WA]

My rear pads also wore out first. They were at 20% when I replaced them (52,500 miles) and the fronts were at 50%.

 

[mustbeaudi]

If shop lets you bring own parts, check out RockAuto.com. I'll send my 5% discount code (or you can google for one). Folks here like some Brit vendor, but I see those prices as high for basic commodity consumables like pad/rotors. BTW, rotors only need replacing on the first go if they're worn beyond spec. I have specs/details if you want them.

 

[jjvd21]

If its not too much trouble, could you post the minimum specs? I'll be changing my pads soon and I'm curious what the minimum depths are for front / rear pads before replacement. Also, the rotor wear information too. Thanks!!!!!

 

[mustbeaudi]

From a document I compiled with instructions based upon several posts, so this portion alone even contains some repetition.

SPECS
Wheel Nuts - 140 Nm (103 lb.ft).
Anchor Plate Bolts - 115 Nm (85 lb.ft)
Guide Pin Bolts - 32 Nm (24 lb.ft)`
Brake Disc Retaining Screw (Torx) - 35 Nm (26 lb.ft)
Brake Hose Retaining Bracket - 25 Nm (18 lb.ft)
Front Brake Hose Union to Caliper - 32 Nm (24 lb.ft)
Rear Brake Hose Union to Caliper - 28 Nm (21 lb.ft)
Bleed Screw - 14 Nm (10 lb.ft)

Front - Brake disc thickness - NEW 27 mm, Service Limit = 24 mm
Rear - Brake disc thickness, NEW = 20.0 mm (0.78 in), Service limit = 17.0 mm (0.67 in)
Disc Run Out - must not exceed 0.3 mm
Pad minimum thickness 3.0 mm (0.12 in)

REAR
Disc diameter on Tdv6 325mm
Thickness new 20mm
Minimum Thickness 17mm
Run out 0.3mm
Pad Min thickness 3.0mm

FRONT
Disc diameter Tdv6 320mm
Thickness New 30mm
Minimum Thickness 27mm
Run Out 0.3mm
Min Pad Thickness 3.0mm

 

[codemonkey]

Thanks, that's some good info there - it's always good to be able to double-check whatever the dealer tells you. I'm stopping in tomorrow to let them look at it, and will decide what to do from there.