247C6Guy

Considering buying my first Vette: a 2005 C6 from a NON GM dealer..Is there a standard GM diagnostic test(s) that I should consider getting from the non GM dealer (hopefully they have the correct equipment).
What do these computer (diagnostic) tests show specifically?
Is there a specific name of this official recommended diagnostic GM test ?
Thanks in advance..I want to lessen the chance I buy a lemon.

Coogster

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schpenxel

I don't see this doing anything other than showing you codes that would already be obvious anyways. Codes will set check engine or airbag lights or 'service traction control' messages, etc. It doesn't stay quiet when things are known to be wrong. The exception being if a tuner has gone in and disabled codes (which can only be done on engine and transmission codes, not airbag, etc.)

Coogster

If this is true then that really sucks. I bought a 2004 Yamaha Four Stroke 115 boat motor I had the diagnostics ran on it it showed everything in its history. The total hours, the RPM's and how many hours in each RPM range from 0 to 7000, plus all sorts of other data in real time and its history. I find it hard to believe the ECM on a 2005 Corvette would be that pathetic.

schpenxel

Yeah you can see hours ran I would think but I doubt you'll get much more than that. I'm sure you can get things like OS #, how many times it has been flashed, etc. But as far as problem goes, I don't think you're going to learn much.

Maybe I'm wrong.. but I've never heard of anyone knowing data like hours in each RPM range. I know that info isn't available in HP Tuners or EFI live, so it would only possibly be factory equipment that would have any chance at doing it. I still doubt it though.

Coogster

What about error codes history?? It sure would be nice to know when and how many error codes have popped up in the ECM.

247C6Guy

Other than hooking into the OBD plug, it looks like there is also a manual way of checking codes as well on the dash (present) and past codes (codes that were thrown previously have an "H" after them)? ...Looks like you can click through codes manually on the dash to see if any pop up ? I really thought that an official GM diagnostic test was available (beyond an OBD plug hookup) or manually checking codes ?

schpenxel

The history codes I know about can be erased easy enough.

Maybe there's more stored than I know about. Honestly, I hope there is..

Hopefully someone like Dano will chime in and give us more info on what GM can see with their tools.

jft69z

Nope. All you can do with GM is scan the modules for active or history codes. If they're cleared, that's it.

Fords have a half-a**ed self test with their KOEO (key on-engine off) and KOER (key on-engine running) routines. It will check various components and report if they don't pass. In the running tests it will actually vary the idle speeds to check things.

247C6Guy

Thanks for the replies guys...Being new here, and a first time owner, I'm trying to be certain that although I'm buying the car from a non GM dealer, I just want to insure I'm getting the best GM standard diagnostic(s) before I take ownership of the car.

Maybe looking at the OBD readings are the only thing available other than looking and listening to the motor ?

247C6Guy

Do GM dealers have special Corvette VIN histories that may NOT show up on Carfax report? The Carfax does show some GM dealership activity however.

jft69z

Any GM vehicle can be looked up to see the service history. It only would apply to work done at a GM dealership. If done at an independent shop, it won't show up.

Ask a local GM service advisor to run the VIN for you and they should be able to help you out.

Carfax is hit or miss. I wouldn't buy a car based on carfax info, or lack of info for that particular vehicle. A lot of things never make it, especially if done at an independent shop, or your own driveway.

247C6Guy

I wonder if most GM dealerships would give you this GM dealer VIN printout for a nominal charge?

jft69z

They should do it free.

You may slip into the conversation that when you do purchase the car, you would like them to be the dealer that services it for you in the future too. They may be more willing to take the 90 seconds it will take to run & then print the report.

Doesn't mean you have to go there after you buy it, maybe that particular dealer has a poor reputation. But if they're very helpful at this stage, it may say something about their customer service.

Worth a shot anyways.

247C6Guy

Thanks for the replies JFT, much appreciated ! Good insights.

jft69z

You're welcome. Good luck & keep us updated on how you make out with it.

247C6Guy

Quick update: I bought the Vette, an 05 silver with removable glass top. The OBD codes checked out, and the VIN history from the GM dealership was good. I appreciate everyone's input and support here, and will post pictures sometime. I look forward to being a part of the fraternity here. Very cool club.

jft69z

Congratulations! Have fun