C5 Diagnostic Codes Through The Driver Information Center - Dashboard Illumination

There are two kinds of DTCs. 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.

Once the system has displayed all the modules, it will go into the "Manual" mode. This allows you to select each module individually using different combinations of DIC buttons. Manual mode can also be entered during the Automatic sequence by pressing any button except "E/M." (Pressing E/M will cause you to exit the diagnostic mode.) When the display shows "Manual Diagnostics," select a module by pressing the "Options" button to scroll forward, or the "Trip" button to scroll back. Once a module is selected, the DTC(s) from that module will be displayed. If more than one code is present, press "Gauges" to scroll forward or "Fuel" to go scroll back. To exit the diagnostic mode at any time, press "E/M."

If you want to erase the DTCs 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 DTCs, 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. The tool will plug into the ALDL, shown here.

We chose the Actron Elite AutoScanner Pro (PN CP9190) for its impressive power and versatility. The AutoScanner Pro can record and graph data, it works on all OBD II-equipped (and most domestic OBD I-equipped) vehicles, and it's even updateable via the Internet. At less than $550, it's also relatively affordable.

Once you've located your C5's diagnostic port, simply plug in your scan tool and follow the on-screen directions. While we don't have room here to list all of the C5 DTCs, you can find them at www.vetteweb.com. Additionally, the AutoScanner Pro boasts a built-in code library.