C5 Diagnostic Display

Attention :   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!!!!

C5 Corvette ---- Dashboard Diagnostics 

The 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 your engine.

The 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.

You can enter the Diagnostic Display mode by using the following procedure:

1. Turn the ignition to the "On" position but don't start the engine.

2. Press the "Reset" button on the Driver Information Centre (DIC) to turn off any existing  warning messages.

3.Press and hold the "Options" button

4. While holding the "Options" button, press the "Fuel" button four times within a 10- second period.

The 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 button !!!!

3. 38 - RTD ( Real Time Damping.  Some models don't have this option )

4. 40 - BCM  ( Body Control Module )

5. 60 - IPC  ( Instrument Panel Cluster )

6. 80 - Radio

7. 99 - HVAC  ( Heater Vent-Air Conditioning )

8. AO - LDCM  ( Left Door Control Module )

9. A1 - RDCM  ( Right Door Control Module )

10. AC - SCM  ( Seat Control Module )

11. BO - RFA ( Remote Function Actuation )

For 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. 

There 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.

If you 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.

Now 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 www.vetteweb.com

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     



c5 diagnostic display