DIAGNOSING
AN AIR SUSPENSION PROBLEM
WITHOUT
A SCAN TOOL
To
diagnose an air suspension problem without a scan tool, its very helpful to know
when the check suspension light is coming on. If theres any doubt how much
time it takes for the check suspension message to come on, simply use a watch
and start timing approx. 3-5 seconds after the ignition is turned on.
If
the "check air suspension" message appears:
......IMMEDIATELY
AFTER STARTING THE VEHICLE, you have a "hard
fault". When the ignition is switched on, the module will do a quick test
of all the circuits and sensors. If it "sees" something that is out
of range or that it simply can't deal with, it will turn the check suspension
message on and shut down the system. After the ignition is turned off, then back
on again, it will try it again. If the module still detects a problem, it will
turn the light on and shut down the system again and will continue to do until
the fault is repaired.
WHAT
COULD BE WRONG?
1)
The problem could be a bad sensor
2)
A bad vent solenoid in the compressor
3)
A bad solenoid in the air springs
4)
In the wiring
5)
Although pretty rare, even a module
It
would be in your best interest to have the codes pulled in the memory to have
somewhere to start. A repair job can get really expensive if you just throw parts
at the car. American Air Suspension has a scan tool for loan on vehicles that
use the Rotunda Super Star II Tester. Click HERE
to find out more.
......45
SECONDS AFTER STARTING THE VEHICLE , this means the module
has "timed-out", or has simply taken too much time to accomplish the
venting goal set fourth by the module. If the module thinks the car needs to be
lower, the module will only try to VENT the car for no longer than 45
seconds before "timing-out".
This means, after 45 seconds, if the car hasn't
vented down exactly where the module thinks it should be, even if its close, if
its not exactly where the module thinks it should be, the module will assume theres
a problem and turn the message on and shut the system down.
WHAT
COULD BE WRONG?
1)
Most likely the vent solenoid has corroded badly and no longer functions properly
(very common Town Car problem)
2)
A damaged or clogged dryer
3)
A crimp or restriction in one or more air lines
If
the vehicle does have a corroded vent solenoid, and the moisture problem is not
addressed, the moisture stands a very good chance of damaging the replacement
compressor. How long the replacement compressor lasts depends on how much moisture
is in the system.
Moisture
can effectively be taken care of by replacing the dryer several times in a 6 month
period, then once a year.
.......90
SECONDS AFTER STARTING THE VEHICLE, this means the module
has "timed-out", or has simply taken too much time to accomplish the
raising goal set fourth by the module. The module will try to RAISE the car for
no longer than 90 seconds before it "times out" or
"gives up". This means, after 90 seconds,
if the car hasn't raised up exactly where the module thinks it should be, even
if its close, if its not exactly where the module thinks it should be after 90
seconds, the module will assume theres a problem and turn the message on and shut
the system down.
WHAT
COULD BE WRONG?
1)
Leaking air springs
2)
A bad compressor
3)
Compressor relay
4)
Although rare, even a module.
5)
Basically anything that will slow down the flow of air in or out of the system
You
need to see if the compressor comes on for "up to" 90 seconds after the ignition
is turned on. If it doesn't come on, you should find out if the big red wire on
the compressor has power during this 90 second period. If you have power at the
big red wire at the compressor, but it doesn't run, replace the compressor.
If the compressor IS coming on, you may have a leak in the system and the leak(s)
maybe leaking more air than the compressor can put back in.
