C5 owners and potential owners. I've received numerous
calls from people after information to help determine a cars
mechanical / electrical fault history. I have put
together this section so you can check on a vehicles past or
present faults through it's on board diagnostics system.
I have found this very useful with my own C5!!!!
---- Dashboard Diagnostics
1990's in America saw the Feds buckle down requiring all
cars and light commercials sold after Jan.1 1996, be
equipped with an onboard diagnostic system including an
"Assembly Line Diagnostic Link," which is used to retrieve
powertrain information with a scan tool. To ease the
diagnostic process, regulations dictate that the ALDL must
be located within 3 feet of the driver and that it does not
require any tools to be accessed. When the system
detects a powertrain problem, it logs it as a fault code in
the vehicles computer memory. When retrieved, this
code provides information regarding the source of the
problem. A "check engine" or "maintenance required"
light illuminates and being able to quickly retrieve and
interpret the fault code behind that "check engine" light
could get you back on the road in a few minutes or even save
Instrument Panel Cluster (IPC) has the ability to display
diagnostic trouble codes (DTCs) from the various modules
that transmit them. For C5's built before 15/12/97,
there are 48 different DTC's; later C5's equipped with the
Active Handling Option have a few more. A full list of
these DTC's can be found in your car's service manual.
enter the Diagnostic Display mode by using the following
the ignition to the "On" position but don't start the
Press the "Reset" button on the Driver Information Centre
(DIC) to turn off any existing warning messages.
and hold the "Options" button
While holding the "Options" button, press the "Fuel" button
four times within a 10- second period.
onboard diagnostics system will go into the "Automatic"
mode, which shows each module's DTCs in a preset sequence:
1. 10 -
PCM ( Powertrain Control Module)
2. 28 -
TCS ( Traction Control System ) commonly known as the yellow
3. 38 -
RTD ( Real Time Damping. Some models don't have this
4. 40 -
BCM ( Body Control Module )
5. 60 -
IPC ( Instrument Panel Cluster )
6. 80 -
7. 99 -
HVAC ( Heater Vent-Air Conditioning )
8. AO -
LDCM ( Left Door Control Module )
9. A1 -
RDCM ( Right Door Control Module )
- SCM ( Seat Control Module )
- RFA ( Remote Function Actuation )
each module, all existing DTC's will be displayed. If
no faults are present in a particular module, you'll see "
No More Codes " on the IPC display.
are two kinds of DTC's. The first is a " Current "
code, which is designated with a letter suffix " C." A
current code indicates a malfunction is present at this
time. The second is a " History " code, which is
designated with a letter suffix " H." A History code
indicates that a malfunction was present at some time in the
past 40 to 50 ignition cycles. A history code could
indicate the presence of an intermittent fault.
want to erase the DTC's in a given module, press and hold
the " Reset " button until the display reads " No More
Codes." Keep in mind that clearing a trouble code
doesn't repair the underlying problem.
that you've retrieved your C5's DTC's, the next step is to
narrow down the possible causes. If you're a DIY'er,
you may wish to purchase a scan tool capable of performing
more-in-depth diagnostics but here in Queensland we use
Performax International at Gympie. They have the right
tools and expertise to solve any of these issues.
While we don't have room here to list all the C5 DTC's, you
can find them at
Additionally talk to club member Dave Kelly, I've heard him
recite all the codes out of his head, I think he has a built
in scan tool !!!!
I hope this
may help some of you, with 7 computers on board the C5 is
more than a car, and if things aren't right the car will
tell you to fix it....
cheers Peter Turner