Range Rover 2.5 need help please

[carsolution]

Hi guys.
I have at my garage a Range Rover with BMW 525 TDS motor.
I have a problem, when I press fast the brake pedal the hand brake light and the ABS light come on.
If I release the brake pedal the lights go off again.
Very strange is the fact it only happens if I touch the brake pedal very fast, if I brake with strenght the lights dont appear.
Any help will be appreciated.
Regards,
Nuno

[Liteace]

If you pump the brake pedal fast you are using all the vacuume in the system that will start the lights flashing as the vac press sensors detect low vac and thinks that the braking system has a problem, My old 1985 Toyota van does the same