BMW 3 (E46). Manual — part 127
300-3
Troubleshooting
Stable handling and ride comfort both
depend on the integrity of the
suspension and steering components.
Any symptom of instability or imprecise
road feel may be caused by worn or
damaged suspension components.
When troubleshooting suspension and
steering problems, also consider the
condition of tires, wheels and their
alignment. Tire wear and incorrect
inflation pressures can dramatically
affect handling. Subtle irregularities in
wheel alignment angles also affect
stability. Mixing different types or sizes
of tires, particularly on the same axle,
can affect alignment and may
unbalance a car's handling.
Table d. Suspension and steering
troubleshooting
lists the symptoms of
common suspension and steering
problems and their probable causes,
and suggests corrective actions. Bold
type indicates the repair groups where
applicable test and repair procedures
can be found.
Table d. Suspension and steering troubleshooting
Symptom
Probable cause
Repairs
Breaking away while braking
Worn struts or shock
absorbers
Replace struts or shock
absorbers.
310
,
330
Car pulls to one side,
wanders
Incorrect tire pressure
Check and correct tire
pressures.
020
Incorrect wheel alignment
Check and adjust wheel
alignment.
320
Faulty brakes (pulls only
when braking)
Check for sticking/damaged
front caliper.
340
Front end or rear end
Worn struts or shock
absorbers
Replace struts or shock
absorbers.
310
,
330
Symptom
Probable cause
Repairs
vibration or shimmy
Worn suspension bushings
(control arm or trailing arm)
Replace worn bushings.
310
,
330
Worn front suspension ball
joints (control arm, steering
arm or steering tie-rod end)
Replace worn ball joints.
310
Unbalanced or bent
wheels/tires Loose wheel lug
bolts
Balance tires.
Check tires for uneven wear
patterns.
Check wheels for damage. .
Loose wheel lug bolts
Tighten lug bolts to proper
torque.
Poor handling, poor
directional stability
Rear control arm or rear
subframe bushings worn or
damaged
Replace rear suspension
bushings as necessary.
330
Rear alignment incorrect
Check and adjust wheel
alignment.
320
Poor stability, repeated
bouncing after bumps,
suspension bottoms out easily
Worn struts or shock
absorbers
Replace struts or shock
absorbers.
310
,
330
Rear end hop with hard
braking
Rear trailing arm busing worn
or damaged
Replace trailing arm
bushing.
330
Steering heavy, poor return-
to-center
Worn upper strut mounts
Replace strut mounts.
310
Incorrect tire pressure
Check and correct tire
pressures.
020
steering system faulty
Check power steering fluid
level.
320
Steering loose, imprecise
Incorrect tire pressure
Check and correct tire
pressures.
020
Loose steering rack mounting
bolt(s)
Inspect and tighten bolts.
320
Worn tie rod end(s)
Replace tie rod(s) and align
wheels.
320
Faulty front wheel bearing
Replace wheel bearing.
310
Worn or damaged steering
rack
Adjust or replace steering
rack.
320
.
Worn tires
Replace tires.
Symptom
Probable cause
Repairs
Suspension noise, especially
over bumps (drumming,
rattling)
Worn front upper strut
mounts
Replace upper strut mounts.
310
Worn suspension bushings
(control arm or trailing arm)
Replace worn bushings.
310
,
330
Worn stabilizer bar rubber
mounts
Replace stabilizer bar rubber
mounts.
310
,
330
Loose suspension subframe
Check subframe for damage.
Tighten mounting bolts.
Tail skid when braking
Rear trailing arm front
bushing worn or damaged
Replace trailing arm
bushing.
330
Tire flat spots
Worn struts or shock
absorbers
Replace struts or shock
absorbers.
310
,
330
Uneven ride height
Incorrect coil springs
Measure ride height.
300
Bent or damaged suspension
components
Inspect, repair/replace as
necessary.
310
,
330
Sagging coil springs
Replace springs as
necessary.
310
,
330
Unsteady in curves,
self-steering, poor rear end
stability
Rear subframe bushings
worn or damaged
Replace rear suspension
bushings as necessary.
330
Differential bushings worn or
damaged
Replace rear suspension
bushings as necessary.
330
Rear shock absorbers worn
Replace rear shock
absorbers.
330
Wheel noise, continuous
growling, may be more
noticeable when turning
Worn wheel bearing
Replace wheel bearing.
310
,
330
Wheel-hop on normal road
surface
Worn struts or shock
absorbers
Replace struts or shock
absorbers.
310
,
330
ABS troubleshooting
ABS is designed to be maintenance free.
There are no adjustments that can be
made to the system. Repair and
troubleshooting of major ABS
components requires special test
equipment and knowledge and should
be performed by an authorized BMW
dealer.
ABS is self-tested by the control module
each time the car is started. Once the
test is complete, the ABS dashboard
warning light turns off. If the light
remains lit or comes on at any time
during driving, a system fault has
occurred and ABS is electronically
disabled. The conventional braking
system remains fully functioning.
When a system or component failure
occurs in the electronic braking and
stability control systems, either the brake
warning light, ABS warning light, or the
ASC / DSC warning light will
illuminate.Troubleshooting and
diagnosis for the electronic braking and
stability control systems must be made
using an electronic scan tool.
Brake bleeding functions, as well as
component coding and initialization must
be completed using BMW scan tools DIS
or MoDiC.
ABS system inspection
A visual inspection of the ABS system
components may help to locate system
faults. If no visual faults can be found
and the ABS light remains on, have the
system diagnosed by an authorized
BMW dealer.
Carefully inspect the entire ABS wiring
harness, particularly the pulse sensor
harnesses and connectors near each
wheel. Look for chafing or damage due
to incorrectly routed wires.
Carefully remove the wheel speed
sensors. Clean the sensor tips. Inspect
toothed wheel on wheel hub. Check for
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