pull codes
Drifting
Joined: Jul 2002
Posts: 1,329
Likes: 8
From: Corpus Christi Tx.
Do-It-Yourself owners will be most interested in the display of diagnostic trouble codes for all 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
4) While holding OPTIONS, press FUEL four times within a 10-second period.
Initially, on-board diagnostics go into an Automatic Mode which shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each
If none are present in a given module, you will see No More Codes on the display.
There are two kinds of diagnostic codes, Current and History designated with a letter suffix, C or ;H. A current code indicates a malfunction is present in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles.When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes.
More likely it's an indication of an intermittent malfunction.
Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module 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 system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons.Manual mode can also be entered during the automatic sequence by pressing any button except E/M. Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present;
press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press RESET
To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONSto go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory.
Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. Unfortunately, it is an expensive set of three books totaling (1997 edition) 3890 pages and stacking 4 1/4 inches high. In spite of its cost and size, the Service Manual is a requirement if you want to understand and work on your C5. They are available through Chevrolet dealers and mail order sources, such as Ecklers and Mid America.
The diagnostics for some diagnostic codes call for a scan tester. Also known as scan tools or scanners these units are really hand-held diagnostic computers. A little larger than a portable cassette recorder, powered by the car battery and connected to the diagnostic link connector (DLC); they collect computer module data and display it on a small screen. Scan testers are operated by a small keypad. Software is usually in plug-in cartridges covering a specific model year.
Where you might get stuck needing one of these pieces of equipment is when the Service Manual calls for operating a specific module with a scan tester. If you are trying to solve a diagnostic code and determine that a scan tester is required but don't have access to one; take the car to a service facility for repairs.
Turn the key to the ON position, but don't start the engine. Clear any existing messages by pressing
the RESET button. Hold the OPTIONS button down, and press the FUEL button 4
times. This will get you into the CODES section of the DIC. The computer will
automatically display all the codes your car has created. It will cycle through
each code every 3 seconds. Any code that ends in H is a history code (something
that has occurred in the past) but is fine now. Once the computer has finished
going through all of it's codes, press RESET to enter Manual Configuration mode.
It should start with a module and show NO CODES or # CODES
To optionally reset the codes once in manual mode, press and hold RESET until it
displays NO CODES Press OPTIONS to go to the next module. Repeat the steps in
this paragraph until you have reset the codes in all the computer modules. NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this.
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
4) While holding OPTIONS, press FUEL four times within a 10-second period.
Initially, on-board diagnostics go into an Automatic Mode which shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each
If none are present in a given module, you will see No More Codes on the display.
There are two kinds of diagnostic codes, Current and History designated with a letter suffix, C or ;H. A current code indicates a malfunction is present in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles.When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes.
More likely it's an indication of an intermittent malfunction.
Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module 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 system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons.Manual mode can also be entered during the automatic sequence by pressing any button except E/M. Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present;
press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press RESET
To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONSto go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory.
Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. Unfortunately, it is an expensive set of three books totaling (1997 edition) 3890 pages and stacking 4 1/4 inches high. In spite of its cost and size, the Service Manual is a requirement if you want to understand and work on your C5. They are available through Chevrolet dealers and mail order sources, such as Ecklers and Mid America.
The diagnostics for some diagnostic codes call for a scan tester. Also known as scan tools or scanners these units are really hand-held diagnostic computers. A little larger than a portable cassette recorder, powered by the car battery and connected to the diagnostic link connector (DLC); they collect computer module data and display it on a small screen. Scan testers are operated by a small keypad. Software is usually in plug-in cartridges covering a specific model year.
Where you might get stuck needing one of these pieces of equipment is when the Service Manual calls for operating a specific module with a scan tester. If you are trying to solve a diagnostic code and determine that a scan tester is required but don't have access to one; take the car to a service facility for repairs.
Turn the key to the ON position, but don't start the engine. Clear any existing messages by pressing
the RESET button. Hold the OPTIONS button down, and press the FUEL button 4
times. This will get you into the CODES section of the DIC. The computer will
automatically display all the codes your car has created. It will cycle through
each code every 3 seconds. Any code that ends in H is a history code (something
that has occurred in the past) but is fine now. Once the computer has finished
going through all of it's codes, press RESET to enter Manual Configuration mode.
It should start with a module and show NO CODES or # CODES
To optionally reset the codes once in manual mode, press and hold RESET until it
displays NO CODES Press OPTIONS to go to the next module. Repeat the steps in
this paragraph until you have reset the codes in all the computer modules. NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this.
Tech Contributor
Joined: Jan 2007
Posts: 19,246
Likes: 1,093
From: Dyer, IN
http://www.c5forum.com/ayc/dtcdic.php
