P12-24

Procedure 12-24
J4500 Ground Clearance Verification and Adjustment
Description:
This procedure outlines the steps to inspect and adjust ground clearance on J4500
coaches that may have an incorrect ground clearance setting.
This is applicable to J4500 coaches MY18 to MY20 within the VIN range: 68377-69754.
Read this entire procedure before beginning work.
Use Safe Shop Practices At All Times.
To avoid personal injury:
a. Proper Personal Protective Equipment (PPE) must be worn. Safety glasses
and protective gloves are required for working with DEF Fluid.
b. Ensure that both the front and the rear wheels are chocked.
c. Positioning the ENGINE RUN and ENGINE START switches on the engine
compartment remote control box to the OFF position prior to working in the
engine compartment.
d. Allow enough time for components to cool down prior to working in the
engine compartment.
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Procedure 12-24
1.0 Material Requirements:
No material requirement.
2.0 Special Tools:
Departure clearance tool kit, MCI P/N: T12-1215 which includes the “Departure
clearance tool”, MCI P/N: T03-3082 and “Grabber tool”, MCI P/N: T03-3083.
Tolerance Band
Front Block for Normal Ride Height, Part of
Departure clearance tool, T03-3082
Grabber Tool, T03-3083
3.0 Verify the Ground Clearance
Start the coach and place it on a level surface.
Make sure all tires are inflated to the correct pressure.
Pump the service brake pedal until Primary and Secondary air pressure gauges
read bellow 100psi.
Let the air compressor engage and re-charge the air system to full governed
pressure. Wait until the compressor shuts off at governed pressure before
proceeding.
Press the “LEVEL CNTRL UP” switch to raise the coach to High Ride. Wait for the
“HIGH RIDE” dash indicator light to stop flashing and remain solid.
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Procedure 12-24
High ride indicator
Level Control Up
Press the “RE-COVER” switch. Wait for the “SUSPSENSIOIN RECOVERED”
indicator to come on. The coach will now be at Normal Ride Height.
Suspension indictor
Re-Cover switch
Place the rear blocks for normal ride height (blue block with the letter “N” on it)
from the kit T12-1215, at the rear jacking points and see if the rear jacking points
are within black tolerance band on the measuring blocks.
Tolerance band
N
Rear block for
normal ride height
Place the front blocks for normal ride height (red block with the letter “N” on it) from
the kit T12-1215, at the front jacking points and see if the front jacking points are
within the black tolerance band on the measuring blocks.
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Procedure 12-24
Tolerance band
N
Front block for
normal ride height
If both the jacking points are within the black tolerance band, then the coach
Normal Ride Height ground clearance is correct then proceed to Section 5.0.
If either one of the coach jacking points is not within the black tolerance band then
proceed to Section 4.0.
4.0 Recalibrating the Ride Height
Make sure the engine is running to maintain system air pressure while completing
this calibration. Connect the laptop to the ECAS unit and run Meritor TOOLBOX
Software. Clear any Fault Messages, if present, before proceeding.
Using the grabber tool from the kit T12-1215, place the Normal Level gauge blocks
under the front and rear jacking points on both sides of the coach. Slightly raise
the suspension, if needed, using the ECAS “CHARGE UP” button to air up the
appropriate airbags.
Front jacking point
Rear jacking point
Slowly lower the coach towards the Normal Ride Level gauge blocks at all four
jacking points until you reach the green line on all four gauge blocks.
Note: Using the suspension air drain valve you can lower the suspension
more accurately for this step.
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Procedure 12-24
Lower the coach
to green line
Now click “Save normal level” on the TOOLBOX window.
Using the TOOLBOX “Charge Up” button, increase front and rear airbag pressures
to High Ride Level. Remove the Normal Ride Level gauge blocks.
Place the High Ride Level gauge blocks (blocks with letter “H” on them) from the
kit T12-1215 under the front(Red) and rear(Blue) jacking points on both sides of
the coach. Slowly lower the coach towards the High Ride Level gauge blocks at all
four jacking points until you reach the green line on all four gauge blocks.
Now click “Save upper level” on the TOOLBOX window. Remove the High Ride
Level gauge blocks.
Place the Low Ride Level gauge blocks (blocks with letter “L” on them) from the kit
T12-1215 under the front(Red) and rear(Blue) jacking points on both sides of the
coach. Using the TOOLBOX “Vent down” button, decrease the front and rear
airbag pressures to 1/2" from the top of the Low Ride gauge blocks.
Using the suspension drain valves slowly lower the coach towards the Low Ride
Level gauge blocks at all four jacking points until you reach the green line on all
four gauge blocks.
Now click “Save lower level” on the TOOLBOX window.
Now click “Finish calibration” on the TOOLBOX window.
5.0 Installing the Customized Ride Height
Turn the ignition off and close the entrance door.
Make sure you have the following two program files on a USB memory stick
attached to the laptop:
-
MDSS Modified Parameters III.ecu.
Updated mux logic 07-18-xxxx.vmm (VIN specific program).
These programs will be provided by the Customer Service Engineering Team
(CSET).
Add the MDSS parameter file using the Meritor Wabco ECAS TOOLBOX software,
then updated the coach logic using VMM software tool. After the download is
complete cycle the Master Battery Switch.
End of the procedure
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