Flashing red exclamation mark (audi 80 cabriolet auto 1999)

[lorriesharday]

Hi.. Can anyone please tell me what the flashing red exclamation mark on the dashboard means?.. It doesnt always happen but it sometimes flashes up for a few seconds when i start up from cold.. thx Lorrie x

[kite]

Low brake fluid.

[acordery]

Hi, Is it the display light that also doubles as the bulb checker thats coming on, if so check the power steering fluid too as for some reason the check is linked to the brakes, Weird!!

[fourringsrus]

THE POWER STEERING PUMP ALSO DOUBLES UP AS BRAKE ASSIST UNIT ,DO NOT USE A/T/F IN THE RESERVOIR OR BRAKE FLUID
MINERAL OIL ONLY!
Stuart

[scorchi0]

Some of these cars run hydraulic assistance for the brakes instead of the vacuum assistance found on many other cars.

The hydraulic system has a pressure accumulator, sometimes referred to as the "bomb" due to it's similarity in appearance to a cartoon bomb. These have a limited service life and the first symptom is the flashing warning lamp at startup. The accumulator should be able to hold enough pressure for about 20 brake applications with the engine off. So, turn off the car and pump the brakes until the pedal stiffens. 20 pumps is factory fresh and if you're down to 4-5, time for a new bomb.

Alternatively, it could just be low on fluid, or in fact you might not even have the hydraulic brake booster!

[scotty33]

The warning can be due to low brake fluid level, low 'hydraulic oil' level or low pressure in the hydraulic system. As stated, the accumulator is supposed to store pressure so the car is ready to go next time it is started, not to mention, to give you some brake assist even if the engine is not running.

A common problem besides the 'bomb'/accumulator failing is that the hyd servo/booster leaks internally, this can be checked by disconnecting the return hose to see if pressure is weeping through the servo. The return hose is the hose that runs from the servo back to the hyd fluid reservoir.

If you undo the pressure hose instead, you are likely to get a high pressure blast of oil in the face!

Like the link says, the servo should be tested before the bomb

http://www.20v.org/brakprob.htm

One other thing to consider is that the pressure switch could be faulty? It's mounted on the Hydraulic Servo, which is the back half of the master cylinder assembly.