Low Accumulator Fault (Non-Latching)

LOW ACCUMULATOR FAULT (NON-LATCHING)

WARNING LIGHTS
BRAKE and ANTILOCK

DETECTION
The accumulator pressure is checked only if there is no LOW FLUID fault pending after the vehicle velocity has passed 3 miles per hour or 3 minutes after start-up.

DESCRIPTION
Low pressure is detected at an accumulator pressure of 1000 psi or less by the dual function pressure switch (DFPS).

The warning pressure switch, which is inside the DFPS, is normally closed above 1000 psi; this grounds pin 17 at the CAB. At or below 1000 psi, the warning pressure switch opens. Inside the CAB, pin 17 detects voltage and thus detects low pressure.

Note that the pump/motor is not controlled by the CAB. The CAB receives a signal from the DFPS for warning pressure and a signal from the starter, but does not provide a signal to the DFPS or the pump/motor relay.

The starter signal is used for two purposes.
- First, it is used by the CAB to detect when the starter motor is engaged in order to ensure illumination of the ANTILOCK warning lamp thus providing a crank mode bulb check.
- Second, the ground path for the DFPS is through the starter solenoid to prevent energizing the pump/motor relay while the starter motor is engaged. This reduces total battery current draw during cranking, particularly during cold weather.