From the ABS manual:
This tell tale will glow red with the ignition switched on, under any of the following conditions:
i) When the parking brake Is applied;
ii) If the brake fluid level is low;
iii) If accumulator pressure is below 12,400 kPa (1,800 psi). If the brake pedal has been pressed
several times with the ignition off, stored hydraulic pressure may fall sufficiently to activate the tell
tale. The electric pump will start up when the ignition is switched on to restore pressure, and the
lamp should go out within 40 seconds.
As a bulb check function, this lamp should light when the ignition is first turned on, and go out when
the engine is cranked. Under normal circumstances, with the engine idling, the tell tale should light when
the parking brake is applied, and go out when released. If the lamp fails to go out when the parking brake
is released, or comes on whilst driving, stop immediately as the brake fluid level or accumulator pressure
may be dangerously low. Only non power assisted non-ABS braking on the front wheels may remain.