DB11 BRAKE FAILURE

[Andysteelmac]

I have a DB11 and had total brake failure whilst driving at speed and have been advised that it's the ABS control unit which frightens me considerably, luckily i was travelling uphill and cruised into a bus stop. Has anyone else experienced anything else similar to this. Surely a fault in an electronic component cannot mean total brake failure, are there no safe guards in place that if an ABS management system fails and you're driving at considerable speed then the consequences could be disastrous.

[silverspeed]

I cannot believe an ABS failure would cause total loss of brakes . What happened if you pumped the brakes ? Did the ABS warning light come on ? Also would the handbrake not work - appreciate it’s electronic but I’m sure I’m there is a procedure for activation in case of emergency - well there is in a Land Rover.

[8Tech]

Normally, in the event of an ABS failure, often due to a faulty wheel sensor, the ABS warning lamp will illuminate and the brakes will works normally without the ABS functional.

There is also a system where the vehicle uses the ABS pump to pressurize the brake system rather than use the older vacuum operated servo. In this case, brake efficiency will be significantly reduced, requiring substantial pressure on the brake pedal to effect any braking, although there will usually be a warning light and a small reserve of applications before you get to that state. (Something like 20 applications).

I am not familiar with the system utilized on the DB11 but anyone who is should be able to diagnose the fault quite quickly.

Numerous German cars at the moment have problems with failing ABS pumps and units. Maybe the DB11 has a German sourced system?

To totally lose the brakes though, you would either need a serious fluid leak or a double failure of both the warning system and the control system at the same time.

8Tech.

[davek_964]

Completely different car, and it wasn't total brake failure - but....

Years ago, I had a 911. Under normal braking it was fine, but anything approaching hard braking caused the brakes to release. Not an ABS style pulsing pedal - a full on release with a rock hard pedal. I sailed through a red traffic light once as a result.

After a about a year of diagnosis and replacement parts, it was eventually fixed by a different garage within 30 minutes without replacing anything. Turned out the ABS used an accelerometer which was sticking due to a build up of dirt - for some reason that resulted in it releasing the brakes.

Obviously the DB11 is a different car and is newer than the car I'm talking about. But I think these systems can be a lot more complicated than just an ABS sensor on each wheel, and even if they fail the software doesn't always know it's a failure.

[john ryan]

I suspect it didn't 'release' the brakes - rather it didn't provide servo assistance, the consequence being much greater pedal pressure required (and the sensation of a rock hard pedal with little retardation). This feels like brake failure, but it isn't.

[Manx V8V]

Again different car but one of the reasons I got rid of my Mercedes a few years back was the SBC braking system, it was basically 'fly by wire' electronic braking and it terrified me.

[Buster73]

Manx V8V said:

Again different car but one of the reasons I got rid of my Mercedes a few years back was the SBC braking system, it was basically 'fly by wire' electronic braking and it terrified me.

Had an E class I bought new in 2003 , brakes failed completely when my wife was driving , she managed to drive out onto a main road without stopping and more importantly not hitting anything.

It was out of warranty so contacted my local Indy who I’d been using for servicing, he collected it and diagnosed it as a faulty SBC system, he dropped it off at the supplying dealer and they replaced it free of charge as a gesture of goodwill.

Sold it a few weeks after it fixed , never had a MB since .

[blueg33]

Andy. You are my parents neighbour! I have admired your DB11. They told me about the brakes.