I have a 99 and have not had any codes since I bought it used in October. What if I get a code? Can I clear this myself or do I have to go to the dealership?. Seems like a lot of owners have code problems. Just wanted a heads up in case it happens to me

 

There's a couple of other code threads on this first page of C5 Tech - scroll down and check out the replies and links for how to deal with them.

 

Codes are NOT the problem! The malfunction that CAUSES the code is the problem! Codes are YOUR key to diaganosing your car. They are VERY easy to look up using the buttons on your dash and easy to clear (if they are not CURRENT and come right back. )

If you did not have DTC's and a DIC to read them you would have to go to a service center or purchase one of those OBDII readers.

Here is how to read the codes.


The IPC display, the 20-character, vacuum florescent screen above the steering column that says "Corvette by Chevrolet" every time you turn on the key, is a powerful device. DIY Service Techs are going to be most interested in the IPC's ability to show diagnostic trouble codes (DTC) for all the modules that transmit them.
The "diagnostic display" mode is entered with the following procedure:
1. Turn on the ignition but don't start the engine.
2. Press the "reset" button to turn off any warning messages
3. Press and hold "options" and
4. While holding "options", press "fuel" four times within a 10-second period.
Inititially, the on-board diagnostics go into the "automatic" mode which shows each module's DTCs in a pre-set sequence:
· 10 PCM Powertrain Control Module page 6-357 - 6-361
· 28 TCS Traction Control system ABS on page 5-86
· ?? RTD Real Time damping page 3-136 (I do not have this option)
· 40 BCM Body Control Module page 8-405 UTD Page 8-727
· 60 IPC Instrument Panel Cluster page 8-508
· 80 radio page 8-213
· 99 HVAC Heater Vent-Air Conditioning page 1-118
· A0 LDCM Left Door Control module page 8-904 to 8-951
· A1 RDCM Right Door Control Module page 8-904 to 8-951
· AC SCM Seat Control module page 8-1064 -8-1082
· B0 RFA Remote Function Actuation page 8-676
For each module, all DTCs will be displayed. If none are present in a module, you will see "no more codes" on the ICP display.
There are two kinds of DTCs, "Current" and "History," designated with a letter suffix, "C" or "H". A current code indicates that the malfunction is present in the system whose module is displaying data. A history code indicates a problem existed in that module sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it is possible it's evidence of a previous problem, now solved, that was not removed by clearing codes. More likely is that a history code indicates an intermittent malfunction. "Intermittents" are the most challenging DTCs. An intermittent may have happened only once, may have happened more than once but is inconsistent in its appearance or may be happening on a regular basis but not at the time the IPC is displaying codes. History codes can also be caused by a current malfunction in a system that is not operating at the time DTCs are displayed. An example is the rear window defogger which doesn¹t operate until the BCM detects engine rpm. For history codes set by a system that does not operate with the key on and engine off, a special diagnostic tool called a "scan tester" is necessary to properly diagnose the malfunction.
Once the IPC has displayed all 11 modules, the system goes into the manual mode which allows selection of each module using combinations of DIC buttons. The manual mode can also be entered at any time during the automatic sequence by pressing any button except "E/M". Once the IPC displays "manual diagnostics," you may select a particular module by pressing the "options" button to go forward or the "trip" button to go back. Once a system is selected and a DTC is displayed, if more than one are present; press "gages" to move forward or "fuel" to go back.
To exit the diagnostic mode at any time, press "E/M". If you want to erase or "clear" codes, press "reset." Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory.
· 10 PCM Powertrain Control Module page 6-357 - 6-361 Domestic
· A=DTC set immediately and MIL is turned on
· B=MIL turned on after 2 consecutive drive trips
· C=After one failure and stored in History MIL not turned on

 

...and here's a site that shows the DTCs specific to each model year:

Computer Codes for 1981 – 2003 Corvettes