Mystery Vacuum Line - Can someone check theirs?
 

(I initially posted this is the performance section before realizing it should go in here. Sorry for the cross-post if I can't figure out how to delete the other one)

I need help identifying where a vacuum line begins and ends on my '04 Alero 3.4L. I discovered, quite accidentally, that the line was broken. I could not find where the other end of it is supposed to terminate.

I looked all through AllData but there is no information on it other than two part numbers (also not sure why there are two part numbers for the same diagram point). Those part #s are 12581196 (Harness, Emission System) and 24508188 (Tube, Crankcase Ventilation).

Still not being able to answer the question of what it is and where it's supposed to be connected on the other end, they had a mechanic come out and look at it. He couldn't figure it out either.

Here is a photo of the top of the engine where one end connects. Can someone take a look at theirs and tell me, with a photo if at all possible, where the other end of the tube should be going?

https://www.dropbox.com/s/vbd0rqy9qh...12.36.jpg?dl=0

Looking at mine it goes up to a spot by the brake fluid reservoir then curves back to the left... I'm just going off a picture on my phone... and i can't figure out how to get it on here lol

I'm pretty sure that's for the HVAC controls.

The PCV line under the throttle calbe bracket is broken too. $14 at the dealer;)

Yeah, the PCV line breaking is what drew my attention to the other thing. I'm fairly confident that the mystery vacuum line isn't HVAC related since this mystery line has been broken for quite some time and the HVAC has always changed between modes just fine.

Hopefully somebody can "put eyes on it" under their hood to see where it goes.

That PCV connector assembly was only $8.75 in Atlanta at a dealer. Either I got a great deal or yours is a ripoff ;-)

http://www.aleromod.com/forums/showthread.php?t=34231

U can see it in one of my pics. I almost think it enters a wire loom and that's how it should get to the hvac controls. I do feel that that is the original hvac vacuum signal.

HVAC for sure, goes into loom and into the interior controls somewhere, have fun

That's interesting cuz when mine broke I code an emissions code for a small leak. Fixed it with some rubber vacuum hose. Simple and easy repair.

Hate to say it but no u didn't. If that line breaks it does not effect evap. If anything it would set bank 1 lean codes.

Now if u had a crack in your purge line and sealed that... That would do as u discribed.

Yes I did. It was a P04.... code. I am in my second year of tech school and know what I saw on the scan tool.

And I'm in my 8th year as a full time GM tech. Plus two years at GMASEP. The only relation between the vacuum line in question (unless previously hacked up) and the purge valve/evap system is the intake manifold there attached to.

The evap system only has ONE line in this particular system and it goes between the purge valve and fuel tank. Vacuum is only applied when the purge valve is open. Manifold vacuum Does not effect the evap system and has no other means of being introduced other then through the purge valve.

Large and small leak tests are performed when our ecm seals the purge valve with vacuum inside the tank. The ecm monitors the tank pressure through the fuel tank pressure sensor and determines a leak when vacuum is lost within a set amount time. The ecm can also set another code for flow during non-purge which happens when the ECM sees vacuum increasing in the fuel system and the purge valve is commanded off.

To put it simply. Leak test are only performed inside the fuel tank/evap system. A leak outside of the evap system (vacuum signal lines, manifold leaks, ect) have no effect on the evap system diagnostics.

yup that's the line that powers your climate controls. Mine broke other day and my controls didn't work any more until i patched it up with some rubber hose. unless a previous owner ended up swapping the controls from vacuum controlled to full electrical