PLUG 5D0303 - Caterpillar

Introduction
This test will determine if the "Low Brake Pressure" indicator is working properly.Required Tools
Illustration 1 g02571852
Table 1
Required Tools
Tool Item Qty Part No. Description
A 1 198-4240 Digital Pressure Indicator
A1 1 198-4234 Digital Indicator
A2 1 198-4237 Pressure Sensor Gp (0 to 3445 kPa (0 to 500 psi))
A2 1 198-4238 Pressure Sensor Gp (0 to 34450 kPa (0 to 5000 psi))
A2 1 198-4239 Pressure Sensor Gp (0 to 41368 kPa (0 to 6000 psi))
A3 1 251-9600 Adapter Cables As (0 to 68900 kPa (0 to 10000 psi))
A3 1 198-4236 Adapter Cables As Test Preparation
Illustration 2 g06199619
The accumulators for the brake system are on the left side of the machine next to the rear wheels. The arrows indicate the location of the pressure sensors monitoring the accumulators.
Illustration 3 g06198793
Location of the brake pressure manifold. The arrow indicates the pressure connector (labeled S1) monitoring the pressure to the accumulators.
Connect 198-4238 Pressure Sensor Gp ( 0 to 34450 kPa (0 to 5000 psi)) at pressure tap "S1".Test Procedure
Do not turn on the engine during this test procedure.
Repeatedly apply and release the brake pedal to decrease the hydraulic pressure in the accumulators.
Verify that the low brake pressure indicator turns on when the pressure decreases to 14480 kPa (2100 psi) on the supply pressure gauge.Note: The brake pedal must be applied slowly as the accumulator pressure approaches the set point to verify the pressure switch.Adjustment Procedure
If the indicator for one or both accumulators is not active at the expected level, determine the status of the accumulator pressure sensors. Review Cat Electronic Technician (Cat ET) or the operator monitor screen in the cab of the truck for active sensor diagnostic codes.If a diagnostic code for the sensors is active, troubleshoot the problem and repeat the test procedure.