Key fob battery drain and squeaky brakes!

[Mark_Bennett]

Correct on the pads - the plates with lugs that slip into the calliper cylinders are for anti-squeal. Did you use the adhesive (pre-fixed) when you installed? Some don't take off the adhesive protective label and use the copper grease direct on the label instead - but I always went with the manufacturer intended way.

 

[BrianJ]

The squeaking could be a small stone lodged against the disc. I've had this several times over the years, sometimes they squeak exactly as you describe and sometimes they make quite horrendous graunching noises. For me, always on the rear. Take the wheel off and look down the back of the caliper from above. There's a kind of natural curve in the caliper where any small stones can lodge against the rotating disc. Last time I had this, the stone was about 2-3mm and I poked it out with a wire. Problem solved. Sometimes you can get lucky and they ping out if you reverse, but not always.

 

[AndyW1973]

I've a couple of issues with my 2004 Boxster S that I'm hoping someone can offer some advice on:

The first is extraordinarily high battery drain on my remote key fob. It's the 3 button type and will drain a battery down to under 3V in less than a week. I've desoldered and replaced all three micro switches, desoldered and resoldered the battery holder and given both sides of the board a good clean with a toothbrush and Isopropyl alcohol. No joy. My next course of action will be to attempt to re-flow the solder on the IC's later this evening just in case there are any cracks. If this is not successful I would be open to any suggestions! Does anyone know of any common issues with the fobs that might cause this problem?

The second issue I have is more an annoyance than a real problem. I think I am correct in saying that the Boxster's brakes 'pre-load' when you lift of the throttle, moving the pads into light contact with the discs, so that braking response is better? Well, when I lift of I can hear a short squeal or squeak that happens briefly once every revolution of one of the nearside wheels. It's not a constant noise, but a sort of squeak, squeak, squeak that gets faster or slower with wheel speed. If I lightly apply the brakes it stops. It only happens immediately, and for a short time after, lifting off. Once back on the throttle it seems to stop after a short while. It is most noticeable when driving slowly in traffic. It doesn't seems to do it at higher speeds, although it may be inaudible due to the higher wheel speeds. I am assuming a bit of copper grease on the back of the pads will stop the noise, but when I changed the front discs and pads a couple of years back I remember the pads having alloy lugs on the back that slid into the caliper pistons. Presumably this arrangement should prevent pad squeal? Confused!

Andy

 

[Glyn]

You appear to have done everything you can with the fob, if the microswitches are disconnecting properly and the fob case is not causing the switches to remain in contact then something on the circuit board must be continuing to drain power. All I could suggest before you purchase a new fob would be to take the circuit board out of the fob and use it separately from the fob, a bit inconvenient but may produce a different result to what your experiencing - its got to be worth a try. The brakes - Never hear of automatic pre-loading when lifting off the throttle, I know racers use left foot braking in order to develop a preload but I don't recall this on any standard road car - and ive had quite a few Porsches. The squeak you hear could be caused by a few issues, When you lift off there is additional weight applied to the front end - so additional load on the wheel bearings and if there is wear this will cause the disk to move a little which causes the pads to come into contact a little more. You don't identify if the squeal is from the front or the rear, but, when you lift off the throttle the rear end looses a little weight - the front end dips a little and the rear rises - have you checked the hand brake is correctly adjusted - When the rear suspension moves up or down it changes the length and could be causing a little more pressure on the cable and applying a little force to the rear brake shoes. Small stones in a rear back plate is common but this usually produces an awful squeal - but usually is constant until the stone is worn down or the stone falls out - but have a look at this anyway. If you hear a squeak, squeak, squeak in tune to the rotational speed you could have disk "run out" and is not running true - choice then is replacement or skimming (dependant on wear being within tolerance) To rule out the hand brake shoes - when you hear the squeak just pull the handbrake on a little - don't use foot brake - if the noise disappears then you know the issue is within the drum and brake shoes - and that's normally one of the springs broken - simple job and cheap to fix.

 

[AndyW1973]

Thanks for the responses. I have now reflowed the solder on the key fob IC's, and will monitor the battery drain over the next day or two - fingers crossed! Never thought of checking for stones stuck in the caliper, but I will have a look. It seems unlikely thought as I would think it would make a constant noise? I will giv ethe handbrake suggestion a go, but as light pressure on the brake pedal instantly kills the noise I would doubt this is the cause. Weight transfer is also probably not a facto as it does it just coasting at low speed. Run out is looking most probable at the moment. Regarding the 'pre-loading'; I read this somewhere and managed to find it again after a bit of digging: From the Design911 website - discussed near the end. Although I'm not 100% sure this applies to my 04 car (although it does have PSM) "PSM = Porsche stability Management (Button Marked “PSM OFF”) PSM, which comes as standard, is an automatic control system that stabilises the vehicle at the limits of dynamic driving performance. Sensors continuously monitor driving direction, speed, yaw velocity and lateral acceleration. Using this information, PSM computes the actual direction of motion. If this direction deviates from the desired course, PSM initiates braking interventions targeted at individual wheels in order to stabilise the vehicle. Under acceleration on wet or low-grip road surfaces, PSM improves traction using the ABD (automatic brake differential) and ASR (anti-slip regulation) functions, giving an agile response. When ‘Sport’ mode is selected on the optional Sport Chrono Packages, the PSM intervention threshold is raised to enable greater driver involvement – particularly at speeds of up to approximately 70 km/h (45 mph). The integrated ABS can further reduce the braking distance. For an even sportier drive, PSM can be deactivated. However, it is automatically reactivated for your safety if either of the front wheels (in ‘Sport’ mode, both of the front wheels) requires ABS assistance. ABD remains permanently active. PSM has been enhanced and now includes two additional functions: precharging of the brake system, and brake assist. If you suddenly release the accelerator pedal, PSM automatically readies the braking system. With the braking system having been precharged, the brake pads are already in light contact with the brake discs. Maximum braking power is therefore achieved much sooner. When sudden braking is detected, the brake assist function applies maximum brake pressure to all four wheels."

 

[BrianJ]

I'm not discounting any of the other suggestions but my last stone squeaked intermittently and then only when driving slowly, particularly round gentle right hand bends. Even gentle application of the brakes stopped the noise. All sorts of conspiracies about the cause but during service nobody could find anything wrong. Kept disappearing for a few days and then reappearing. 6 months and about 10k miles later I eventually took the rear wheel off and found the tiny stone. Problem solved, no money spent.

 

[Mather]

Key fob battery drain

I have exactly the same problem with Key fob battery drain on a 04 boxster s 550 spider anniversary, edition, but it is also the same on my spare key.i am reluctant to buy a new fob (£120+) if it is something on the car

 

[AndyW1973]

Reflowing the solder on both the IC's on the key fob board completely cured it for me. Just a dab with a soldering iron on each of the pins until the solder melts and reflows is all that is needed. It's likely the repeated flexing on the board over years of keypresses creates breaks in the solder joints. Good luck! Andy

 

[B7owa]

Did you ever get to the bottom of the squeaking I have exactly the same thing, wondered if the stone removal method required more than just removing the pads as I have tried this one already to no avail but my squeak sounds very much as described on my Cayman.

 

[AndyW1973]

I have yet to solve the squeaking on mine. I removed and copper greased the back of the pads (even though they have anti-squeal lugs) and checked for stones and found nothing. I've always thought the squeak was coming from the nearside rear, but I haven't yet ruled out it actually coming from the nearside front. At some point I'll make the effort to check that out.

 

[B7owa]

I'm sure the squeak is near side rear on mine too and I have tried taking out the pads and re-greasing but to no avail. When it was mentioned about stones do you think the disk needs to come off too?

Also tried with the hand brake on slightly but still squeaking.

 

[AndyW1973]

Possibly, but I could clearly see the gap between the caliper and the disc edge and it was clear of stones. Applying the handbrake on mine did not stop the noise, but lightly touching the pedal does stop it, proving it is the disc/pad interface causing the noise. As mine stop a few minutes after releasing the brakes I'm guessing the pad is just close enough to make light contact until the piston in the caliper gradually retracts back into the caliper. Might have to try jacking the back end up and spinning the wheel after pressing the brakes to try and pinpoint exactly what is going on! I'm going to wait for warmer weather though....

 

[B7owa]

Exactly what I am planning to do but similar to your problem it's only after the brakes have been on and at low speed.

 

[AndyW1973]

Just to follow up on this post....

My squeaking has got a little bit worse recently, accompanied by a new issue. Leaving the car overnight, even with the handbrake off, resulted in some alarming clunks from the rear wheels whilst reversing out of the drive. The handbrake shoes appeared to be rusting on. I decided to invest in new rear discs, pads and handbrake shoes as they were due for replacement anyway and proceeded to strip down the brakes before the new parts arrived. Upon removing the old discs I found this......

Notice the friction material inside the disc that has detached from the shoes. It was the same on both sides of the car......

 

[BartyB]

Andy, I'm currently experiencing the same problem with my 2004 S' eating its key fob battery. It was working fine until it ran out of juice a couple of months back and I changed its battery. Since then, all replacement batteries have been draining within 3 or 4 days. I've replaced the microswitches, examined the circuit for cracks or shorts under a microscope, all to no avail. With a fresh battery, the fob operates normally, opening doors, boots and setting the alarm. A second key fob works perfectly suggesting the fault is with the fob and not the car. Sadly, replacement seems the only and therefore expensive resolution. Just one more frustration in the long-term Porsche ownership experience.

 

[AndyW1973]

I experienced exactly the same symptoms as you. All looked fine on the board with no cracks, etc visible. Reflowing the solder on the chip completely fixed it for my - It's on the same battery I put in after my follow up post above, written in May 15. I melted the solder on each pin in turn and had no more problems. Definitely worth a try!

 

[BartyB]

Thanks for the input Andy. It looks like I'll be getting my trusty Antex out again then.