A few years ago my sister hand an ECM replaced on her '09 LT 2.4l. Soon after she began experiencing odd electrical problems and OBDII error codes. Most recent error codes would be P0014 (VVT) and P0128 (coolant) among others such as ABS. In addition, OBDII often will not read (unfortunately also experienced twice at emissions inspection). Continue on with intermittent electrical issues ranging from gauge cluster randomly spazzing with erroneous readings to A/C and turn signal (RF) intermittently not working. The latter along with an SRS always lit warning light condition could very well be issues of their own.
My focus is on the random error codes and gauge cluster malfunctions. Seemingly I've been able to temporarily cure these woes on a number of occasions by interacting with the cluster of connectors located on and near the BCM. I initially disconnected, cleaned, and tightened up some of the wider gaped BCM terminals (and cycled the other co-located connectors) which usually works for a short while. Not sure if this is due to a computer reset cycle or if I'm actually identifying the problem as faulty connections. The reason I'm focusing on terminal connections is I suspect a fair bit of terminal probing (gaping) was conducted during the week it took the shop to determine it was a faulty ECU.
My hope is that someone can identify a commonality among the bulk of issues I've related. I should note -- The vehicle did receive the TSB repair at the BCM years ago. I believe it was intended to extend the harness which was strained. Unless it was simply to reposition the harness I can see no evidence of modification other than there is an unused snap on t-type splice connector added to the yellow wire just before the BCM connector, could have been added during TSB or ECM repairs.
The battery was replaced recently (about 9 months ago), well after these anomalies had begun to occur as we've been chasing these on and off for a few years. My hope is that there's a common connector/junction or control module related to the bulk of mentioned faults that I could target for closer inspection. To cover all bases I did just perform a static, load, and crank draw test on the current battery and it easily passed.
Check all the ground points and use a electronic cleaner / lubricant in the connectors. A good manual will identify these ground points, there are many.
The fretting corrosion sticky in the beginning of the Gen 7 section covers the issues of that in these cars in module connectors.
Wasn't aware of the fretting issue that seems relatively prevalent, enough so to generate a bulletin. I does give me some hope that a thorough clean, tweak, and greasing of the terminals could possibly provide a positive result. I'll address all the connectors/terminals already mentioned along with any others I can access both in the passenger compartment and under the hood..
Interestingly, I was a tech for many years with Mitsubishi (both in MD and FL) and while we never experienced normal-use fretting issues there were major terminal issues during my Florida stint. These all arose from vehicles which were previously involved in flooding, moisture induced corrosion was the culprit.
I'll be sure update after I secure some time to give it another go. ;-)