7
Diagnostics
26
Meritor
Maintenance Manual 14R (Revised 12-18)
The main air pressure drops to
65 psi (448 kPa), cannot release
the brakes.
There is a hole or tear in the air
spring.
Check for the correct clearance and determine the cause of
the air spring damage. After the cause has been remedied,
replace with the correct air spring. Check the shocks for
damage.
There is insufficient air pressure
supplied to the suspension tandem.
Build the air pressure to 65 psi (448 kPa) or more. Check
the compressor for correct function. Check all the air lines
and fittings leading to the suspension tandem for leaks.
Repair or replace as necessary.
There is an air leak within the
suspension tandem due to loose
fittings or air lines.
Verify that adequate pressure is being supplied to the
suspension tandem. Check all the air lines and fittings
leading to the suspension tandem for leaks. Repair or
replace as necessary.
The ride is harsh.
The ride height is incorrect.
Check and adjust the ride height.
The air springs are flat.
Refer to the recommendations for flat air springs.
The tire clearance is incorrect in
full jounce.
The tire size is incorrect.
Replace the tires with the recommended tire size. Contact
the original equipment manufacturer for tire size
specifications.
The trailer is not pulling straight,
dog-track.
The trailer axles are out of
alignment.
Realign the axles. Refer to Section 4 in this manual.
The slider lock pins will not
retract.
The trailer parking brakes are not
set.
Set the trailer parking brakes before the lock pin control
valve is activated.
One or more lock pins are stuck in
the body rails.
Release the tractor brakes only and rock the trailer back and
forth to free the lock pins.
The lock pin control valve is leaking
air or not passing air to the actuator.
Replace the lock pin control valve.
The lock pin actuator is leaking air
when activated.
Repair or replace the lock pin actuator.
The slider lock pins do not fully
engage.
The slider is not aligned with the
body rail holes.
Release the tractor brakes only and move the trailer back
and forth until all four lock pins are fully engaged in the body
rail holes.
The lock pin control valve is leaking
air or will not reset when the trailer
parking brakes are released.
Replace the lock pin control valve.
Condition
Possible Cause
Recommended Action
