- Apply the parking brake.
 
- Drain all of the reservoirs. Refer to 
Draining Reservoirs 
.
 
- Start the engine and run the engine at a fast idle.
 
- Verify that the low pressure tone alarm is on.
 
| •  |  If the tone alarm is not on when first charging the system, test
 the brake warning system. | 
 
| •  |  For diagnosis of the brake warning system, refer to Brake Warning
Alarm Inoperative. | 
 
- The low pressure tone alarm should turn off when the dual air
 pressure gauge indicates 470-510 kPa (68-74 psi).
 
| •  |  If the tone alarm does not turn off, test the brake warning system. | 
 
| •  |  For diagnosis of the brake warning system, refer to Brake Warning
Alarm Always On. |