Bleeding Procedure
- Ensure ignition switch is off throughout bleeding or false trouble codes could be set to memory. Deplete brake booster by pumping brake pedal several times. Assure master cylinder is full. Install 2 bleed valve tools (J 35856) on 4WAL EHCU at high pressure accumulators (HPA). See Fig 2.
- Install one bleed valve tool on combination valve. There are internal bleed valves on each side of EHCU module as shown in Fig. Fig 2. Bleed valves are used to open internal passages within the EHCU module. Back off the 2 internal bleed valves to 1/4-1/2 turn.
- Use conventional bleeding process for pressure, vacuum and pedal bleeding. The EHCU module should be bled after replacement or if trapped air is thought to be in unit. It should not be necessary to bleed EHCU module if fluid has not become contaminated or if no air is thought to be in module. Module should be thoroughly bled BEFORE wheel cylinders and calipers in event EHCU module does need to be bled. There are 2 bleeders on front of unit that look like normal brake bleeders. These are modulator bleeders for bleeding EHCU module and they must remain closed when unit is not pressurized.
- To bleed EHCU Module, if required:
- Slowly depress brake pedal one time and hold.
- Open one modulator bleeder on front of unit until fluid flows clearly or pedal is depressed.
- Close modulator bleeder and tighten to 60 INCH lbs. (7 N.m). DO NOT OVER TIGHTEN.
- Slowly release pedal.
- Wait 15 seconds. Then repeat procedure on remaining modulator bleeder on front of EHCU module until all air is purged from the unit.
- Always maintain full master cylinder. Bleed wheel cylinders and calipers. Remove 3 bleed valve tools. Close left internal bleed valve and tighten to 60 INCH lbs. (7 N.m). DO NOT OVER TIGHTEN. Close right internal bleed valve and tighten to 60 INCH lbs. (7 N.m). DO NOT OVER TIGHTEN.
- Start vehicle and evaluate brake pedal feel. Continue with procedure if firm. If pedal is soft or spongy, reinstall tools and re-bleed system starting with 1). Any re-bleed due to soft or spongy pedal should always include bleeding EHCU module.
- Perform normal diagnostics using Tech-1 Function procedure. Road test vehicle.
CAUTION:
Failure to follow procedure accurately may result in
immediate soft pedal after first anti-lock stop and
repair induced stored codes.