LowRyter

I've been experiencing a CEL for a couple of years due to purge valve / EVAP code. The valve, pigtail and gas cap have been changed out and smoke tested. The CEL keeps coming back on. I would occasionally disconnect the battery to reset the CEL but it would come back on after a couple a weeks and recently, after a couple of days. I finally just stopped fooling with it and left the CEL on.

Now today, I start the car and hear a loud chime and the CEL goes out. Huh?

I am guessing someone here knows what's going on or perhaps the car is haunted?

bartsky

Could be fixed after the changing of parts and a drive cycle

LowRyter

It must've been a dozen tankfuls and battery disconnects since the last change out of purge valve.

The chime was a real surprise.

LowRyter

anyone?

LowRyter

anyone here know why the dashboard chime would signal clear of CEL?

z06clif

thats my guess

Clif

Bruze

Didn't anybody actually READ his post(s)?

LowRyter

It's been 5 days and the CEL is still off. No experts here have made comments regarding the Chime

In other news, "Generalissimo Francisco Franco is still dead".

Bruze

They obviously MISSED your entire post #3 that you've had a dozen or so tanks through it and still have a problem. "You need to change more parts and have a couple of drive cycles."

LowRyter

I can understand that the drive cycle theory is a valid idea. But why the chime? Why didn't the CEL stay cleared when the parts were changed out (twice over two years) or after the many times I cleared the codes by disconnecting the battery?

Why has no one else here experienced it?

Bruze

I have no idea, I'm hardly the expert on modern cars. I had a CEL a month or two ago that was the purge valve thingy, new part, light stays out.

SOMEBODY here can help with this (Dano?) and will check in I'm sure.

owc6

What exactly are the codes?

The chime being part of it seems odd, frankly.

Dano523

Its the C184 connector that is next to the battery half way down on the fender side (or could be the ecm connector instead) .

The short version since I have 05 opened up in GM SI, purge vavle that is in front of the motor on the passanger side, C2 connector out of the fuse box, hits C8 connector, hits the EVAP canistor, then drk gr/white is the negitve side back to the ECM for ground on on C2 50 pin (ecm controls the ground, and does the ohm/voltage check to make sure it sees the evap).

The other set of wires for the vent solenoid on the passenger side rail next to the tank, Rd/white out of the fuse box on D5, hits the C184 connector, S420 splice block, C420 connector, hits the EVAP canistor, then white wire on the negitive side back through the C420 connector, theC184 connector, then lands at the ECM on C1 pin 54 (and again, ecm controls the ground, and does the ohm/voltage check to make sure it sees the evap) .

2005 C6 Evap wiring diagram is any one want to down load a PDF of it,
http://www.mediafire.com/file/lbo3b1...iring.pdf/file

And for later years which is pretty much the same, but with different landing pins and connector on the ECM instead.
2008 LS3 evap wiring
http://www.mediafire.com/file/jgzuq6...ring_.pdf/file

2008 LS7 evap wiring
http://www.mediafire.com/file/ndaat0...iring.pdf/file

The C420 connector is the Transmission harness to fuel tank harness, the underbody at RR frame rail, while the C184 connector is right next to the battery, with the S420 around 7" from the C184 connector instead.

So short of a problem with the ECM connectors just needing to be pulled and cleaned with the problem there, you can bank that the problem is the C184 connector that needs to be pulled apart and cleaned isntead. And again, its about half way up to the fender side of the battery, and while you in there, a couple more main connectors with lots of wire that you may want to pull the connectors apart and clean as well.



LS2, but you get the jest of where the main connector are located.
http://garage.grumpysperformance.com...nds-etc.10092/

On my car, since the rear wheel hub sensor wires run through the C186 connector in the same location, when it gets wet by me power washing under the hood and behind and to the side of the battery once a blue moon, becomes the anti-Christ connector until it dry back out, getting DTC codes for lack of communication with the rear wheel sensors isntead.

________________________________________ ___________________
As for glitch I have with GM designing while going over this, is that the maintenance free battery will vent, the pressure in the engine bay areas will push pressure down the sides and out the front fenders vent and bottoms, why in the name of all that is holy, did GM not put a battery venting/splash guard over the side connector and above the ecm connectors in the first place. Worse when the battery does fails and puke's, So the acid from the battery does not reach the connectors there nor the ECM connectors for that matter below.

Hence splash cover is nothing new for GM, since they stick one over the NPP vacuum solinenoid in the rear bumper area, but they can't install one over the connectors/over the ECM connectors next to the battery isntead.




My take since I'm on a tangent and have the industry size spray can to paint the world black tonight, both of the above are more about product obsolescence isntead.
The Cover over the NPP solenoid helps to trap heat in so the Npp solenoid burns up faster/has to be replaced more often, and the lack of splash/vent guard over the connectors (and there placement next to the battery in the first place, with a open direct path to the ECM connectors as well) is so if the battery does fail and pukes, more work for the GM techs for needed repairs on connectors as well.

LowRyter

wow.

Although unrelated to the Chime and CEL, quite an explanation I am not sure where those connectors are located in the photo, but I did have the pigtail under the rear fender replaced when the purge valve was changed the 2nd time.

Dano523

The C184 connector is next to the battery and in the cubby hole on the fender just past the red battery cable cover in the photo.


The C420 connector is on the on the rail side, and to the right of his hand when he is pointing to the canister vent solenoid.


As for the valve and vent systems, the valve/vent in the diagrams that I posted links to, are for two different items.

The canister purge valve on the far left of the page in the wiring download that I posted links for, if for this one right in front of the passenger side valve cover, hence wiring out of the engine block, to the purge valve connector, then straight back to the ECM connector.



The canister vent control second line from the left on the wiring download links I posted, is the one that is at rail passenger side next to to transmission on the back side of the car, and it wires go through a bunch of connectors isntead (C184 S420, C420, hits the vavle connector, then back through C420, C184, then hit the ECM connector-pin. Look at the tanks cross over tube on the passenger side as our reference point as your looking up from the back of the car.



As for the new canister purge valve when you replace it, they changed the connector for it on the new ones, and will notice that when you buy the new one, you get the little pig tail converter for it as well.

Hell most of the time when you think the canister purge valve bad, a quick test will tell you if it bad or not. With it in hand, suck through it to start with, then put 12v power to its two pins, should hear it click, and should not be able to suck through it powered up. So powered up, and not begin able to suck through it, it's fine, and you have a wiring problem isntead if a P0449 code. As for my tangent, the wiring problem 99% of the time when it happens, is at the C184 or ECM connector, due to the battery venting or spilling acid to these connectors. The other 1% wiring problem, with the canister purge valve connector itself, or the added adapter pig tale connector they add with the new one ,or right there at the C184 connector isntead.


As for pigtail and connectors in the rear bumper cover area, all of that is for rear lighting, and guess that you had lighting problems back there that needed to be resolved. If you take a look at the photo pointing at the canister vent solenoid, the two wires for the solenoid only come out a short distance from C420 connector before they jump out the main harness and become the connector for the solenoid. Hence these wire do not continue on farther.

So the reason that you kept getting the P0449 code once in a blue moon, is that you have an intermittent wiring problem on the canister vent solenoid wiring. Hence the reason that the ecm throws the P0449 code, is when it goes to close the vent solenoid (since it is controlling the ground side of the circuit), its not getting the correct resistance reading for the circuit when it grounds out the loop to close the solenoid).


Now to answer your haunted car problem!!!!!!!!!!!!!!!!!!!!!!!!!!!
As for the chime and CEL going out, this happens when the wiring connection does self-heal itself (for how long is the question).
If after 4 starts and run cycles of the car and the canister vent solenoid/ P0449 passing each start up test , the ECM will clean the CEL and the chime was to let you know the car cleared the code itself (will still still show up in the old DTC list for a while when you check with a tech II, but since it passed the last 4 test, will not show up as a CEL in the dash instead).

So I would say for now with the car has "self healed itself of the the wiring problem", your may be out of the wood for a while, but if the code/CEL comes back, you know where to start looking for the wiring problems.
I'll give you a hint, and if you wash the engine bay area around the battery, and the P0440 code comes back, its in the C184/ECM connector that water is causing the ECM resistance reading problem when the ECM goes to close the canister purge valve and gets back the wrong resistance reading on closing the circuit .

Hence got to love the C6 Electrical Gremlins, since there such a "Ball of Joy" to track down and resolve when the happen.

LowRyter

Thanks for the the trouble shooting info. When I said "pig tail" I was referring to the connector to the purge valve unit.

I assumed that it was a connector/ground somewhere. The CHIME was a real surprise

Dano523

On the purge valve problem with a bad connector,broken wire, or it burnt out, you get the P0443 code isntead.
Hence on the download link for wiring, it's the far left hand line labeled canister purge valve.

P0443 Evaporative Emission (EVAP) Purge Solenoid Control Circuit ECM



That a lot easier to trouble shoot since you don't need to get under the car, since either the purge valve is burnt out, or you have a problem on the Fuse 14, pink wire from the fuse box to the purge vavle connector, or the G-gr/wh wire on the purge vavle connector that that goes back directly to the ECM connector for the control ground side isntead.


So that one is really easy to figure out the problem, and you just put the car into Run mode, motor off, use a tech II to close the purge valve, the break out the test light.

Clip the test light clip to Negative battery terminal on the car, then probe the Pk wire on the connector and make sure the test light light ups. Test light does not light up, you have a problem from the connector wiring back to the fuse 14 in the fuse box somewhere.

Now clip the test light to the battery positive terminal, and probe the D-gr/wh wire on the connector to see if the test light lights up. Test light does not light up, and you have a problem from the connector wiring to the ECM connector (or ecm taking a noise dive) instead.

Test light lights up both test, its the purge valve that needs to be replaced and cause the break in the circut.

LowRyter

OK, the CEL came back on today. I took the advice listed here and removed the battery and sprayed the connectors with contact cleaner.

I screwed up and didn't position the blue clamp correctly on the big connector. So the car wouldn't run and I got some kind of traction control notice on the dash. Took it back apart and saw the blue clamp wasn't closed. Put it back together and the car started right up. A short drive and car learned the tire pressure and traction button started to work. Reset the clock., etc., etc.

So we'll see if the CEL stays off.

Thanks for the advice.

LowRyter

CEL is back on