| Tools to help diagnose issue: ET data log, VIMS snapshot, etc. |
| (11) Valve (Brake Pump Unloader) (12) Solenoid Valve (Brake Pump Unloader) (13) Relief Valve (Main)(14) Solenoid Valve (Brake Accumulator Purge) |
| View A-A (11) Valve (Brake Pump Unloader) (12) Solenoid Valve (Brake Pump Unloader)(14) Solenoid Valve (Brake Accumulator Purge) |
| View B-B (13) Relief Valve (Main)(14) Solenoid Valve (Brake Accumulator Purge) |
| View C-C (11) Valve (Brake Pump Unloader) (12) Solenoid Valve (Brake Pump Unloader) (13) Relief Valve (Main)(14) Solenoid Valve (Brake Accumulator Purge) |
| View D-D (11) Valve (Brake Pump Unloader)(12) Solenoid Valve (Brake Pump Unloader) |
| Problem: EID 526 Brake Pump Pressure Not Responding to Command is active if the engine is running, and the brake system is commanding a charge, and pump pressure is less than 2100 kPa (304.6 psi) for more than 0.5 seconds. | ||||
| Component | Possible Component Root Causes | Non-Component Root Causes | How to Diagnose | Corrective Action |
| Solenoid Valve (Brake Pump Unloader) (12) | Seal Damaged causing leaking. | Contamination: Brake system oil significantly dirtier than ISO 18/15 | Hook up ET and compare the time from Unloader Status changes to how fast the brake pump pressure rises. If the pressure rises too slowly, the valve could have an internal failure. | Replace Solenoid Valve (Brake Pump Unloader) (12). |
| Valve improperly installed causing screen damage | Make sure that oil is ISO 18/15 or better. If more than two ISO codes high, kidney loop machine and change filter. If kidney loop not available, change oil. | |||
| Slow to close | Stuck Open: Measure actual brake pump pressure. Install 5000psi gauge on brake pump pressure tap. Brake pump pressure at standby constantly. | |||
| Partially stuck open | Remove the access plug for OR1. Install a 5000psi gauge. Pressure at OR1 is less than (stuck open) brake pump pressure. | |||
| Bent or damaged solenoid valve. | Remove solenoid and visually inspect screen for damage. | |||
| Valve (Brake Pump Unloader) (11) | Stuck Open | Contamination: Brake system oil significantly dirtier than ISO 18/15 | Hook up ET and compare the time from Unloader Status changes to how fast the brake pump pressure rises. If the pressure rises too slowly, the valve could have an internal failure. | Replace Valve (Brake Pump Unloader) (11). |
| Remove the access plug for OR1. Install a 5000psi gauge. Pressure at OR1 is the same as (stuck open) brake pump pressure. | Make sure that oil is ISO 18/15 or better. If more than two ISO codes high, kidney loop machine and change filter. If kidney loop not available, change oil. | |||
| Slow to Close | Stuck Open: Measure actual brake pump pressure. Install 5000psi gauge on brake pump pressure tap. Brake pump pressure at standby constantly. | |||
| Remove valve and visually inspect to determine if valve stuck open | ||||
| Relief Valve (Main) (13) | Stuck Open | Contamination: Brake system oil significantly dirtier than ISO 18/15 | Stuck Open: Measure actual brake pump pressure. Install 5000psi gauge on brake pump pressure tap. Brake pump pressure at low pressure constantly. | Replace Relief Valve (Main) (13). |
| Make sure that oil is ISO 18/15 or better. If more than two ISO codes high, kidney loop machine and change filter. If kidney loop not available, change oil. | ||||
| OR1 Orifice | Orifice Plugged | Remove OR1 Access plug and inspect. | Remove OR1 Plug and basket screen from port. Flush orifice and reinstall | |
| Remove the access plug for OR1. Install a 5000psi gauge. See if pressure is slow to build in the OR1 Port | ||||
| Brake Pump Pressure Sensors | Failed In Range / Stuck at one pressure | With machine off, verify that the sensors are reading less than 75psi. | Replace Brake Pump Pressure Sensors. | |
| Install 5000psi gauge on the brake accumulator pressure taps in order to verify that the accumulator pressure matches the gauge pressure. With machine running at low idle check to see if the gauge matches the sensor in ET. | ||||
| OR1 Orifice Basket Screen | Screen Plugged | Remove OR1 Access plug and inspect. | Remove OR1 Plug and basket screen from port. Flush orifice and reinstall | |
| Remove the access plug for OR1. Install a 5000psi gauge. See if pressure is slow to build in the OR1 Port | ||||
| Filter Element | Damaged on Installation | System Overheating | Remove filter element and inspect for damage and loose pieces of yellow plastic. Remove and inspect Accumulator purge solenoid screens for debris. | Contact product support through the DSN. |
MARYGAR
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