>>>> What would ABS do, to make a noise, if the brakes are not applied :smile:


Hmmm....Good question! I'm not an ABS expert but here goes my understanding of the system and why the FAQ might contain plausible information in the response.

The three main components of the ABS system are (1) the wheel speed sensors, (2) the ABS electronic control module and (3) the ABS hydraulic unit. The wheel speed sensors continually send rotational data to the ABS control module. Under extreme braking, the control module will assess the wheel speed sensors (a number of times per second) to determine if any wheels are rotating slower that the others (a.k.a. impending locking up). If this is the case, the control module will signal the hydraulic unit to maintain/release hydraulic pressure to that wheel's caliper (again in fractions of a second). There are electrically-operated solenoid valves within the ABS hydraulic unit that actually perform the pressure modulation.

If you have ever felt the ABS system in operation, you have noticed the rather loud pulsing noise when the brakes are automatically modulated; it is suprisingly loud. That noise is actually the sound of the solenoid valves opening and closing.

Thus, a "system check" (perhaps done every X miles or X starts?) may include a split second partial activation of the solenoid valves with a "check status" returned to the ABS electronic control module to verify their proper working order. This brief, partial activation of the solenoid valves could well be the THUMP we hear.

However, I didn't write the FAQ response but am trying to apply a little deductive reasoning to understand its plausibility. Now if we could exactly identify the location of the ABS hydraulic unit, we'd have some better info. I'm betting its somewhere inside the left boot side panel.

My two pence,

Theo


_________________

 

Is it not in the cavity in front of the passenger seat under the bonnet, with all the brake lines going in and out

 

the thump only happens for me when i go over a certain bump coming home from work... and only when i accelerate over it... has anyone called mini usa about this? bizarre!

 

>>the thump only happens for me when i go over a certain bump coming home from work... and only when i accelerate over it... has anyone called mini usa about this? bizarre!

 

Mystery. Solved.

 

I don't think an ABS brake test should make any noise. Have you made sure that all your stuff is tight? Ie. your jack etc? Perhaps your wife/gfriend could sit in the back while you drive over the spot...

-donut

 

>>Is it not in the cavity in front of the passenger seat under the bonnet, with all the brake lines going in and out

No. That is the DSC unit. And while the DSC system makes use of the ABS system (primarily the wheel speed sensors), it does have its own control and hydraulic units. Shine a flashlight into that cavity and read the labels on the hydraulic unit. I believe you will find it labelled "DSC".

Theo

 

>>>>
>>Mystery. Solved.
>>
>>:evil:

jeskiddn... please don't cen.........................................
_________________

 

>>I don't think an ABS brake test should make any noise. Have you made sure that all your stuff is tight? Ie. your jack etc? Perhaps your wife/gfriend could sit in the back while you drive over the spot...
>>
>>-donut
>>
>> I don't think an ABS self test makes any noise,My MINI makes no noise other than the door locks going through their cycle, it is turned off so it only makes a thump every
launch,don't pay to much attention to it

 

>>I don't think an ABS brake test should make any noise. Have you made sure that all your stuff is tight? Ie. your jack etc? Perhaps your wife/gfriend could sit in the back while you drive over the spot...
>>
>>-donut
>>
>> I don't think an ABS self test makes any noise,My MINI makes no noise other than the door locks going through their cycle, it is turned off so it only makes a thump every
launch,don't pay to much attention to it

 

>>>>>>>>
>>>>Mystery. Solved.
>>>>
>>>>:evil:
>>
>>jeskiddn... please don't cen.........................................
>>_________________
>>

 

>>>>>>>>>>>>
>>>>>>Mystery. Solved.
>>>>>>
>>>>>>:evil:
>>>>
>>>>jeskiddn... please don't cen.........................................
>>>>_________________
>>>>


He's the president of Afganistan....just north of Michigan I think

 

>>

Theo

P.S. The banner came from Halliburton's billion-dollar Military Sign Procurement Center.

_________________

 

My car also has the thump. And like the rest of you, it doesn't happen all of the time. It happens long before the doors lock, just as I am pulling away. I think it has even happened when backing out as well as pulling out forward.

 

>>>>We've noticed a sound like a knock or creak in the back. Seems to happen when the body flexes when turning on an uneven surface. Hasn't happened with enough predictability to track it yet but I would first suspect it's coming from the hatch moving relative to the body.
>>
>>I think if you hear it while turning on uneven surfaces it may be roof flex you are hearing. It seems I read somewhere that the Mini's with the sunroof tends to pop while turning into uneven driveways etc.... :smile:

 

>>>>
>>You boot has *****? I don't follow this.

Yaaup, and it takes bigger ones to dirve

 

>>>>>>>>>>>>>>>>
>>>>>>>>Mystery. Solved.
>>>>>>>>
>>>>>>>>:evil:
>>>>>>
>>>>>>jeskiddn... please don't cen.........................................
>>>>>>_________________
>>>>>>
>>
>>
>>He's the president of Afganistan....just north of Michigan I think
>>

>>
>>
>> How far north, maybe I can vote too

 

Hmm, sunroof flex. That thump drives me crazy. It is so loud, and happens so irregularly that it is hard to diagnose. It always happens when I first start out in the morning, and always happens when I'm turning.

I'm going to go with the sunroof flex for now. Though that doesn't entirely make sense, since the noise is definitely coming from the boot area. But, the sound is consistent with sheet metal or some material "popping" out and flexing. Sort of like the top on a baby food jar does.

 

Just to clear things up a bit on the ABS/AS+T/DSC issue:

Regardless of whether or not you car has ASC or DSC, and since all cars have ABS, the valve cluster that you see in the right-side cowl cavity handles it all, whether you have ABS or DSC, etc. The big difference when it comes to having DSC over just ABS is in additional system capability.

The ASC/DSC controller is able to apply brake pressure to any particular wheel regardless if you are pressing on the brake or not, whereas ABS regulates existing braking pressure to prevent a particular wheel from slipping (ASC/DSC controllers also work as ABS). Put simply, DSC can apply the brakes to help prevent a car losing control in a corner even if the driver is not braking, ASC does similar but only on acceleration, and all three work to control wheel slippage when braking.

All these systems perform a self test periodically the first time the car is driven past 12mph after the engine has been started. All ABS-equipped cars perform a similar test periodically regardless of make. Since the ABS system sits in a 'stand by' mode until needed, and since the system itself is quite complicated with numerous wheel speed sensors, pumps, solenoids, pressure switches and vales and microcontrollers, a full test of all of these pieces need to be done so that the system will be ready when needed.

Most people can drive for thousands of miles and never call upon the ABS system. If the system has never been tested in the meantime, there could be a chance that something may go wrong when it is most needed. Self-testing the system by reading input from the wheel sensors and cycling the valving while reading the status of the valving and other parts of the system ensure that it is ready when needed. If something is found to be wrong, the system is shut down, the ABS warning light is turned on, and the test results/failures get stored in memory for the technician to diagnose later. You will have braking, but no ABS functions.

 

thanks Greatbear ,now what is that thump these folks are hearing,anyone :smile:

 

Well heck, I still vote for the roof flex thing. When my 03 MCS started making this popping noise some months back I contacted Minihune in Hawaii because that's where my MINI came from. I consider Minihune THE MAN when it comes to questions concerning the MINI.

Minihune told me he thought the sound was from the sun roof area of the roof.

Does any MINI owner have this popping sound that DOES NOT have the sun roof option????

I hear the sound only when turning a corner or when driving up or down uneven turn in's to a driveway or parking lot. But then not everytime does this happen.

 

Well, I just proved myself wrong this morning. I backed out, turned my corner, and was going completely straight when I hear the THUMP! coming from the back. I mean, imagine if you had a bowling ball in the back and you turned a corner and it smacked against the side of the car. That's what this Thump sounds like.

I suppose it's possible that there is something with the ABS, but I just don't know what would be in the back of the car that would do that.

 

Hey, aren't you the one who's related to Tony Soprano?

Get rid of the bodies, that should help!

 

I always thought it was the gas cap locking or something along those lines. At least that is where I seem to hear the noise eminating from.

 

I don't have the sunroof and I do have a similar sound. Mine is right away though, I back the car up (in the garage) about two feet and I hear a thick metallic clicking, from below/behind me. It sounds a lot like a brush gaurd plate setting back into place.