Vent Valve Issues 2012 Chevrolet Malibu
Got a call to come program a PCM on a Chevy Malibu. The customer had stated that they had replaced the vent valve and a code still existed. Seeing that it was a circuit failure, I doubted that it would do any good. I went ahead and updated the calibration to the latest. As expected the code remained.
Looking at the wiring diagram, I saw that there was one wire from the trunk fuse box that fed the vent valve and another that went from the vent valve to the PCM. Before lifting the vehicle, I disconnected the battery and checked continuity to the fuse and the fuse itself. It was all good to there. I then measured the resistance from the positive lead to the White vent valve wire at the PCM. It was showing "OL" or out of limits. I surmised that there was an open based on information so far. The vehicle was then raised with the battery connected and Ignition on. At the vent valve there was a few hundred millivolts. At the body connector X413 there was 12.5 volts. So it appeared there was a problem in the wiring between the vent valve and the body connector X413. Further inspection of the wiring revealed the culprit. The winter's snow and ice melt found a chink in the wiring's armor. I had the technician helping me pull on the wire. It broke easily. What was once nice Copper was now Green powder. The wire was repaired and codes cleared. No return of the code.
There's a couple guys that make good diag videos and they use the term "green crusties" when wiring corrosion sets in.
We call it the green monster...
One of my early mentors referred to these as "nose goblins"...
What terminology do you use?
Verdigris-a-fication, Y'all :O)
We call it 'green death'. :)
Thanks for sharing.GM does have a history of putting critical electrical components in places prone to the hazzards of road crud.
This totally blows me away too. Every time I deal with something like this I just have to shake may head and thank the engineers for such a good pay check
When I see wires like these I remember when used to work at the gm plant and seeing that every harness comes in a box with a big warning sticker that says " do not use sharp objects to open box" or something like that, can you guess what every worker on the line uses to open the box ? Yep : utility knife
Thanks for your case study. This is why piercing wires is such a bad idea.
Hi Mike: The owner of the shop, where I worked on Peugeots, used to say that the eyes are a mechanic's best tools. Good grab. BTW, it appears there is some consistency here. The white wire looks like it's been stabbed also. Guido
Mike, Nice case write up! I will surmise most of us believe connection resistance and wire probing issues will continue on a steep growth curve! Even today, I still see wire "stabbing" tools included in electrical testing kits.