2005 Vue 3.5L codes, rough starting P0340 P0386

[inardan]

I spent a considerable amount of time on this platform searching for solutions to my 2005 Vue's rough starting, stumbling, and persistent check engine lights. Through my research and with a spare 3.5 engine and harness at my disposal, I undertook the following steps to eliminate possibilities:

Substituted the camshaft position sensor with a known good one.
Replaced the crankshaft position sensor with a known good one, along with its sub-harness.
Cleared the codes, which would return immediately.

Despite my efforts, there was no improvement, but since I had the components on hand, it did not cost me anything. I then devoted an entire day to inspecting the engine harness and the fuse box underneath it.

Next, I checked the three pins of the camshaft position sensor connector for continuity with the ECM (the larger of the two connectors), starting with my spare engine, and then the problematic one. There are three wires - white, brown/yellow stripe, and yellow. This test revealed that my spare (known good) engine had THREE pins for the brown/yellow wire, while the problem engine had NONE.

Beginning at the camshaft position sensor connector, I removed a section of its three-wire harness and several inches of the larger harness into which it fits. I discovered that two additional brown/yellow wires connected to the first wire, which explains why there are three pins for it at the ECM.

This section of the harness is located in a plastic trough with partial coverage, allowing dirt and moisture to seep in. I noticed green corrosion where the second brown/yellow wire joined the first one, and when I touched that connection, it had corroded through.

The fix was simple, but finding the problem was difficult! All of the codes and starting difficulties have now vanished, and as an added bonus, this was also the source of my cruise control problem several weeks ago!

Having owned six 2004-2007 3.5L Vues, I found this platform to be quite helpful and decided to share my findings here, as it appears that others may have experienced similar issues.