GM Corvette 1984-1996 Repair Guide

Bleeding The ABS System

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auto bleed procedure

1995-96 Vehicles



On 1995-96 vehicles, if the proper pedal height and feel is not achieved after the regular bleeding procedure is completed, you must perform the Auto Bleed procedure. This procedure requires the use of a Tech 1®, or equivalent scan tool.

The auto bleed procedure is used to provide a complete brake system bleed on 1995-96 vehicles, which are equipped with Bosch 5 ABS. The procedure cycles the system valves and runs the pump to purge air from secondary circuits which are normally closed off during non-ABS/TCS mode operation and bleeding. This procedure is primarily to be used when it is suspected that air has been ingested into the system secondary circuits, or when the Brake Pressure Modulator (BPM) valve has been replaced with a new unit.

In order to perform this procedure, you will need the following:



Tech 1® or equivalent scan tool with MSC.
 
A pressure bleeder capable of producing at least 30 psi with suitable adapters and filled with the proper type of brake fluid from a sealed container.
 
A hoist, or jack and stands to safely support the vehicle.
 
A suitable bleeder bottle to receive the vented brake fluid. The bottle should be unbreakable plastic, with a clear plastic hose that fits snugly on the bleeder valves. The hose should protrude into the bottle, with its end immersed in brake fluid.
 
An assistant to pump the brake pedal during the procedure.
 
Proper attire, including safety glasses.
 

The auto bleed procedure may be stopped at any time by pressing the "EXIT" button the scan tool. No further prompts pertaining to the bleeding procedure will be given. After pressing the "EXIT" button, relieve the bleed pressure and disconnect the bleed head from the master cylinder, making sure to follow the bleed equipment manufacturers directions.

  1. Raise and safely support the vehicle.
  2.  
  3. Remove all of the wheel and tire assemblies.
  4.  
  5. Check the brake system for leaks or component damage. Make sure to fix all conditions before starting the bleed procedure.
  6.  
  7. Make sure the vehicles battery is fully charged.
  8.  
  9. Connect the Tech 1® scan tool to the DLC.
  10.  
  11. Turn the ignition switch to the RUN position, but do not start the engine.
  12.  
  13. Establish communications with the scan tool and select ABS/TCS system features.
  14.  
  15. Press "F4: Misc. Tests"
  16.  
  17. Select "Automated Bleed Procedure"
  18.  
  19. Bleed the brake system, as outlined earlier in this section.
  20.  
  21. Press the "UP" button. This conducts several tests which determine whether the ABS/TCS system condition is such that the bleed procedure can be performed. If any malfunctions are found, the bleed procedure will be aborted. If DTCs are present, the scan tool will display "DTCs PRESENT", or list the DTCs, depending upon when the codes were set. The codes can be displayed or cleared as necessary in the "F2: Trouble Codes" mode. Make sure to correct any system malfunctions before trying to repeat the bleeding procedure.
  22.  
  23. Connect the pressure bleed equipment, following the manufacturers directions, then press the "UP" button.
  24.  
  25. Apply bleed pressure, minimum 30 psi. Check for leaks at the master cylinder reservoir bleeder cap and fix, if necessary.
  26.  
  27. Have an assistant pump the brake pedal continuously from this point on, with long, steady strokes. Press "UP" on the scan tool.
  28.  
  29. Open the left rear bleeder screw, use the bleeder bottle. Press "ENTER" when prompted. Press the "UP" button.
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