P0449 - 2008 Chevrolet Impala

Hello there!
2008 Chevrolet Impala, former police car

First of all, thanks for the super informative videos on testing the EVAP Solenoid circuit on GM vehicles. I've watched several of them now and feel like I've followed the test procedures close enough to have tracked this down as a shorted driver.

Symptom: P0449
Evap Vent Solenoid was replaced in a shop last winter

The connector has a white wire and red with white stripe.

I don't have a scantool or test light to test further, so I'm using my hand multi-meter.

Probing the connector, plugged into the solenoid, with the key to on/not running gives 12v on red lead, 0v on white lead.
Not the coil, not the connector

At this point I disconnected the battery and made room to access the PCM in the air intake area, but left the PCM connected.

Connected MM to battery positive and disconnected the connector from the solenoid, key off.

Tested for voltage on white white with EMC connected / 12v (7b), next step to disconnect PCM and see if it's 7c or 7d

Disconnected PCM, 0v now detected on white wire. (7d) shorted PCM

However, just for giggles I connected the MM to the red lead on the connector and saw 12v, which I didn't expect with the battery disconnected and the PCM also disconnected. There shouldn't be a path to ground on this side, correct? Could there be more going on with this? Should I go back and verify those results because them seem awful odd?

At this point I'm certain it needs to go to a shop, but I'm curious as to why the red lead now indicates 12v. Thought I'd bounce this off of you for some ideas and what to possibly expect from the shop.

Thanks!

Kevin

Hi ,

Ok you have a code that is p0449 , the code is telling you you have a circuit problem.
The way to test a circuit is by loading the circuit. You need to have a test light or make one from a head light. Hook the wires to the plug at the vent solenoid (unplug it and do not damage the pins in the plug)
if the light comes on then you know that the PCM and the wiring is all good. If it does not turn on try and new ground . If it still does not light you need to check closer to the pcm for a bad wire or check at the pcm to see if the pcm is in dead bad.

You cant test with just a DVM the first rule in testing circuits is to load it.

If you test a wire with a DVOM you know that it may have one strand good but that does not tell you that the wire as hole can handle the load.

You ca get a head light and solder a sewing machine needle on the end of the wire and use it to back prob it works well…..


good luck
Doc.

Doc,

Thanks for the tip. I was following the procedures ScannerDanner has outlined in this video and this video .

I'll probably pick up a test light eventually, or make one for the dozens of spare bulbs I've got lying around that have proven to be less than useful as the vehicles in my garage have changed a bit. Maybe it'll be warm enough this weekend and I can take a shot at it with a homebrew light. If i do I'll post back here with the results.

Thanks!