October 2020 – issue 1
Page
28
of
29
Section 7 - Trouble Shooting (continued)
ZERO EMISSION CITY BUS Owner’s
Manual
7A.3 - Steering:
Fault
Possible causes
Trouble shooting
Steering still /
noisy and / or
not self -
centering after
turning
Low tyre pressure
Check tyre pressure and adjust as required
Lack of lubrication in king-pins and steering ball
joints
Raise the front axle onto stands ensuring the
king-pins have no load on them. Grease the king
pins and steering ball joints
Lack of power steering oil
Check oil level in reservoir is sufficient
Steering shaft universal joints seized on shaft from
steering wheel or shaft to steering box
Inspect universal joints and replace if failed
Failed steering pump
Replace steering pump
Stiff or seized tie rods ends
Replace tie rod ends
Loose fasteners on tie rod ends, drag link or steering
box
Check and re-tension if necessary
Steering wheel
not centralized
or too much
free-play
Wheel alignment incorrect
Reset wheel alignment
Worn tie rod ends or damage to the steering link
Check steering system for damage or wear and
repair as necessary
Loose nuts on tie rod ends or drag link
Check and re-tension as necessary
Loose steering wheel retaining nut
Re-tension nut
Uneven tyre
wear
Incorrect tyre pressures
Check and reset tyre pressures
Incorrect wheel alignment settings
Re-set wheel alignment
Failed shock absorbers
Check and replace shock absorbers
Bus wanders on
road, driver
continually making
adjustments to
compensate
Incorrect ride height settings
Set vehicle to correct ride height
Stiff king-pins or tie-rod ends
Check and repair as necessary
Stiff or seized steering shaft
Inspect both shaft universal joints from steering
wheel to steering box
Excess free-play
in steering
Possible steering box adjustment required
Adjust steering box free-play
Air solenoid valve is broken, valve is always open.
Replace with a new valve.
7B – Body:
Fault
Possible causes
Trouble shooting
Entry door not
opening or
closing
No air pressure in system
Start vehicle and build up air pressure
Incorrect connection in air pipes.
Emergency door valve is in the on position
Turn off the emergency door valve under front
nearside of bus
Door control unit is broken.
Replace door control unit.
Vehicle isolator switch is OFF (no power).
Turn ON vehicle isolator switch
Air pipe connection is broken and air leak off.
Find the broken position, replace new pipes.
