The C5 IPC code reading /clearing program that is built into the IPC can read and clear anything a code reader scanner can do.

Remember... EACH time you clear a fault/DTC you start the mandatory drive cycle test over again and the EMISSIONS READY FLAGS will not be ready.

If theres an issue, just clearing the fault/DTC will NOT solve the issue and the DTC/fault will come back.

READING YOUR Engine Diagnostic Trouble Codes (DTC)

This procedure should be carried out any time you experience a problem with your C5. Most inexpensive store bought aftermarket code readers will ONLY read power train DTC’s. Reading the DTC’s with the C5 built in code reader will allow you to read ALL the modules in the vehicle.

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. (i.e. door open, trunk open ect)
3) Press and hold the OPTIONS button
4) While holding OPTIONS, press FUEL button four times within a 10 -second period.

Initially, the on-board diagnostics go into an Automatic Mode which will cycle through each module and 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 module. ( i.e. PCM = 4 codes) If none are present in a given module, you will see No More Codes on the display.

There are two types 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 OPTIONS to 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. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles. There are a few body module DTC’s that if set will prevent the module from operating properly. Once the DTC is cleared, the module will return to full function. This is not true for power train DTCs.

If you have never read and cleared your codes, there will probably be a lot of old history DTCs. It is recommended that you clear your codes and see if any come back during a driving cycle. Those are the ones that you need to concentrate on diagnosing.

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. The Service Manual is really a requirement if you want to understand and work on your C5.

NOTE and a WARNING. You can read the DTCs while the engine is running. I pull mine up all the time while driving.
WARNING. Don’t become distracted while reading DTCs while your driving and cause an accident!!!!! Use common sense and drive safe.

These are some very good C5 Diagnostic Trouble Code (DTC) explanation web sites!!! They also explain how to read the DTCs

Here are some very good sites that explain what DTC mean:

http://www.gearchatter.com/viewtopic11755.php

http://www.obd-codes.com/trouble_cod...d-ii-codes.php

Make sure to include the H or C suffix when you post your DTCs!!

 

Hi,

Thanks for the offer. I have an OBDII scanner/reader I picked up at the first of August. Is that what you have? Tomorrow I am going to work from home and try Bill's suggestion of cleaning the connect points on the ignition switch. Then I will drive it for a few days. If that does not reset the IM monitors, then I will go and try to get the MIL monitor test for at least the CATS tuned out. I will let everyone know tomorrow what I find on the ignition switch.

Thanks

 

The last post in my ignition switch thread has been updated with some great info. Check it out.

Your not to far (well at least on a texas map) from Houston where ENGLANDGREEN is. Call Stephen or Jason and see if they can help you tune that stuff out if it comes down to that.

Bill

 

Keep us up to date on how everything goes. If HP tuner would be something you would want to do let me know.

 

I'm telling you this is the exact scenario I had, the CAT and EVAP tests would never set and there were never any codes to read. It appeared as if everything was working correctly and that I just needed to set the drive cycle. I drove 1000 miles and the CAT and EVAP tests never set.

I wonder if there is another option to fixing this before replacing the ECU. At the time I could not find my HPTuners cable so I bought the ECU off of ebay for $100 already flashed to my VIN, no problems since then.

 

Hey Guys,

I redid the ignition switch yesterday and plan on driving it today so lets see what happens now. I had cleaned the switch about a 1 year ago so I was not surprised to see a really clean switch. It only had two contacts that had little burn marks on them. We will see.

I will post back later.

If this does not work after a few days of driving. I am going to find a turner that can at least tune out the CAT IM monitor test.

Thanks
Aaron

 

You should find someone that can exercise the EVAP system to see if it's working. The valves can be commanded open/closed to see if the respond.

 

I might if the ignition switch does not clear up the problem. How can it be done?

Thanks
Aaron

 

That test or operation can be done with a GM TECH 2 or one of the snap-on similar devices.

 

I heard that there's a proud owner of a GM Tech II, who lives somewhere near the CT shoreline.

Too bad oneshot doesn't live closer. In less time than it took to do all this typing back and forth, his problem would have been fixed for good!

 

Yea,, I have a TECH 2 ,,,,,, BUT,,, it has NEVER been updated and needs a new card with the latest calibrations. I have to work on it this winter and get the stuff to update it. Stuff that your learn the HARD way!

 

There is someone in the area where we are that can tune out the cats. I sent him a pm so he has that option available.

Dave

 

Hey Dave,

Yup I got the PM, I am going to call Brian next week and see about setting up an appt if the cleaned ignition switch does nothing for me.

Thanks for the info.

Aaron

 

I just went through this with a friends car. His car had a colder thermostat than stock, and the monitor tests would not run because the ecm did not see engine operating temperature. Does your car hit normal Vette running temps? There are requirements that need to be met before the monitor tests will run. He spent a ton of cash replacing parts that were never bad, I just replaced the stat with a stock one, and boom...all tests went right through. If you had a voltage or ignition problem, all of the monitors would reset, not just these 2. Hope this helps, good luck.

 

Excellent info. Thats where data logging helps diagnose the issue. You can see if its in open or closed loop and the status of NUMEROUS other operating systems and their status.

BC

 

That's good information, and certainly worth considering.

In this case however, with the extreme heat in TX where oneshot lives, outside temperatures have been consistently over 100 degrees for weeks. I can't imagine ANY C5 not reaching operating temperature when it's over 100 degrees outside!

 

Absolutely Correct!!! Just driving down to the corner store my car hits 196 degrees according to the temp read out. Most mornings it is 80+ degrees outside so if anything my car might not get cool enough. lol!

 

Update:

I have driven it 4x times since cleaning the ignition switch and no dice. It still shows the CAT and the EVAP IM Monitors as not ready. So I will drive it some more over the next couple of days and see. If by Thursday it still does not work, then I am going to get the CATs programmed out of the PCM and see if that gets me legal.

Thanks

 

Do a search in the Tech section on OBDII Readiness monitors. Lots of good info. Went through my own issues a few years back. If the car runs good, rather than continue to screw around with trying to figure this out by shotgunning parts, get in touch with a tuner and have them go into those two systems and set all DTCs on these two systems to Not Report. This will automatically make these systems go into a Ready state and you will pass inspection. There very well may be issues with your PCM but who knows. Setting all DTCs in these two systems to Not Report will work. Good luck with it.

 

oneshot i notice you are in Round Rock. drive your car up here to Bell County in Killeen. i doubt any shop in town will test for what you are having problems with. i dont have any cats on my car and i had it inspected in july at the jiffy lube off of Stan Shulder Loop & Robinette Rd. hit me up in a pm if you do come up here, i am right around the corner.