Q: Hello, I am a longtime Corvette enthusiast and have owned many Corvette models. Unfortunately, I have never been in the financial position to purchase a new model and usually buy cars between 10 and 15 years old. My newest purchase is a C5. It has a check engine light on and I was looking for the connector to install the jumper wire (paper clip) to retrieve the fault codes. The connector does not look like the one in my C3 Corvette. Is there a way I can retrieve the fault codes without having to purchase an expensive scanner?
A: Hello, David. Congratulations on your purchase. I think you will find the C5 Corvette to be a great vehicle and fun to drive. Accessing the fault codes in a C5 are different than older Corvettes. The federal government required that all cars and light trucks built and sold in the United States after January 1, 1996, to be OBD-II equipped. With the new regulations came new equipment.
All 1996 model year and newer vehicles must use an OBD-II connector also known as the Assembly Line Diagnostic Link (ALDL). This connector is common for all automotive manufacturers, making the retrieval of information more universal when a scanner is used. According to the government guidelines, this connector must be located within three feet of the driver and must not require any tools to be revealed.
The need for you to be able to diagnose the fault codes is important because the fault could be as simple as a loose gas cap or something that could cause more serious damage if the engine is not stopped immediately. There is a way for you to find the codes in the computer’s memory by using the programming buttons on your dashboard. The following easy-to-follow directions will guide you through this task.
The Instrument Panel Cluster (IPC) has the ability to show diagnostic trouble codes (DTC) for all the modules that transmit them. The IPC display says “Corvette by Chevrolet” every time you start the car. Its principal function is to display warning and status messages from the various modules. For cars built before December 15, 1997, there are 48 warning or status messages. A few additional messages come for cars built and/or equipped with the Active Handling option after this date. A list of the warning/status messages can be found in your Service Manual.
The “diagnostic display” mode is entered with 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 Center (DIC) to turn off any 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 on-board diagnostics 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.
3. 38-RTD, Real Time Damping. Some models do not have this option.
4. 40-BCM, Body Control Module.
5. 60-IPC, Instrument Panel Cluster.
7. 99-HVAC, Heater Vent-Air Conditioning.
8. A0-LDCM, Left Door Control module.
9. A1-RDCM, Right Door Control Module.
10. AC-SCM, Seat Control module.
11. B0-RFA, Remote Function Actuation.
For each module, all DTCs will be displayed. If no faults are present in a particular module, you will see “no more codes”on the IPC display.
There are two kinds of diagnostic codes. 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 a malfunction was present at some time in the past 2 to 50 ignition cycles. A History code could represent an intermittent fault.
Once the system has displayed all of the modules, the system will go into the manual mode, which allows the selection of each module using 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. Once the display shows “Manual Diagnostics,” select a module by pressing the “Options” button to scroll forward or the “Trip” button to scroll back to a different module. Once a module is selected, a code is displayed, if more than one code is present; press “Gauges” to scroll forward, or “Fuel” to go scroll back to a different code within that module. To exit the diagnostic mode at any time, press “E/M.”
If you want to erase the trouble codes in a given module, press and hold the “Reset” button until the displays reads “No More Codes.” Remember, clearing a trouble code does not repair a problem. You are simply erasing the evidence of a fault in that specific module’s memory.
David, some diagnostics may need more than just knowing the fault code, so a scanner may be needed perform in-depth diagnostics. I think you will find that all scanners are not a major investment and may actually save you money when a repair can be performed at home.
When choosing a scanner, you will want one that will give you fault codes, a live data stream, and will work on OBD-I and OBD-II equipped vehicles. I hope that will get you started and enjoy your new Corvette.