Thread: Buzzing after braking

Originally Posted by acgmarketing

After braking I hear a short (1 second maybe) buzzing from the passenger side engine bay. Sounds like could be ABS repressurizing something? It's not the SLS air compressor as I know its tunes!

I have just replaced master brake cylinder but thought I'd followed correct bleeding process. Any clues from those who've had similar or have ideas?

It sounds to me like it might be Traction Control kicking in.
Does it tend to occur on braking when the front wheels are turned, or perhaps if there is an irregularity in the road surface?
I know you don't get long to look, but see if you can catch the TC dash light on when it happens ('cos I think it does come on, if it is the TC working).

Cheers

I experience this as well - has baffled me for years. I had posted about it on here and thought at one time that had i fixed it when i replaced a dud left front steering drag link but no it still happens but is less frequent. I too feel that its ABS related but it's just a guess. Are your front tyres pressures equal - that was the first thing i checked.

Originally Posted by AndrewMilne

It sounds to me like it might be Traction Control kicking in.
Does it tend to occur on braking when the front wheels are turned, or perhaps if there is an irregularity in the road surface?
I know you don't get long to look, but see if you can catch the TC dash light on when it happens ('cos I think it does come on, if it is the TC working).

Cheers

Hmmmm! Traction Control

Is it when you come to a stop? I hear what I think is a servo in the climate control unit, perhaps activated by manifold vacuum.

Originally Posted by onebob

I experience this as well - has baffled me for years. I had posted about it on here and thought at one time that had i fixed it when i replaced a dud left front steering drag link but no it still happens but is less frequent. I too feel that its ABS related but it's just a guess. Are your front tyres pressures equal - that was the first thing i checked.

Hi Onebob,
Like you, I was puzzled (and a bit worried) about this sound for some time, and posted questions about it on this forum, a year or more ago.
Several people suggested that it might have been gurgling due to air in the cabin air heater core, but it did not sound quite like that, to me.
Eventually, someone suggested that it might be TC working for short periods.
So I waited for it to happen a few more times, and tried to catch the TC dash-light flickering when it did.
As I recall, I did spot that on one or two occasions, and stopped worrying about it.

Now, it hasn't happened for a long time!!
Cheers, Andrew Milne
PS: Mine is a 2003 D2a TD5 Auto, no ACE, no SLS

I'll watch again but doubt it's TC as it happens after I've come to a stop rather than while stopping and I'm familiar with TC being operated. Seems almost like something in the ABS is repressurising as the buzz goes up in pitch when it operates. Also doesn't need foot still on brake pedal for it to happen. can only juuuuust hear it from driver position but can hear it when I'm in the co-pilot spot.

Originally Posted by acgmarketing

I'll watch again but doubt it's TC as it happens after I've come to a stop rather than while stopping and I'm familiar with TC being operated. Seems almost like something in the ABS is repressurising as the buzz goes up in pitch when it operates. Also doesn't need foot still on brake pedal for it to happen. can only juuuuust hear it from driver position but can hear it when I'm in the co-pilot spot.

OK - if the sound occurs or continues after you have come to a stop, then I agree that it is most likely something else (i.e.: not TC).
I thought it was happening as you came to a halt.

When you find the cause, I for one would be very keen to know what this is, so please let us know!

Originally Posted by AndrewMilne

OK - if the sound occurs or continues after you have come to a stop, then I agree that it is most likely something else (i.e.: not TC).
I thought it was happening as you came to a halt.

When you find the cause, I for one would be very keen to know what this is, so please let us know!

UPDATE on this old topic thread .... I have had the glovebox and associated kick panel removed for a while (planning for the SLABS upgrade over xmas) and have found the source of the buzzing sound. It’s a servo motor on the blower motor that moves the blend flap. I notice the buzzing noise when I drive without the climate control unit operating OR if i have been using the climate control and then turn it off. In my experience the flap cycles [open / close] continuously when the interior gets warm and stuffy and will not stop until the ignition switch is returned to (OFF) position 1. First thoughts are that the climate sensor and the servo power supply are controlled separately to the Climate Control Unit. Shouldn’t be too hard fix with a relay, so that the servo power is switched by the relay when triggered by the blower fan operation .... ideas anyone ??