2010, multiple PCM issues

[withku]

Hey all, my 2010 has been acting up lately. A while ago, my a/c stopped working intermittently, air just got hot and humid. I reset my APIM , and that solved it for a couple weeks. It’s back to working about half the time. I checked codes though ForScan, and my PCM isn’t receiving the required voltage, and multiple other modules lost communication with the PCM, including my APIM. I checked my battery and alternator, both are good. Bad PCM? What are your thoughts?

Edit: I’m getting multiple U100x codes, and P1602, but they are intermittent as well. They show up when my ac shuts off.

 

[glockcoma]

I didn’t have any symptoms but upgraded when I did an audio upgrade.
Check Ground wire passenger side near the strut tower.
mine was corroded and was very brittle and basically disintegrated when bent.
It goes from the strut tower area to the top of the manifold.

 

[withku]

I didn’t have any symptoms but upgraded when I did an audio upgrade.
Check Ground wire passenger side near the strut tower.
mine was corroded and was very brittle and basically disintegrated when bent.
It goes from the strut tower area to the top of the manifold.

mine was fine

 

[glockcoma]

I would check the physical PCM then under the wiper cowl.
check for chewed wires or compromised wiring/harness.
wiper arm removal tool is highly recommended so you don’t accidentally crack the windshield.

 

[withku]

I would check the physical PCM then under the wiper cowl.
check for chewed wires or compromised wiring/harness.
wiper arm removal tool is highly recommended so you don’t accidentally crack the windshield.

Will check PCM when I can. Did you see my edit?

 

[SHOrod]

How old is the battery, and how did you determine it's fine? If the battery is 3 or more years old, I'd consider replacing it before investing in a PCM or other more expensive component. The batteries in these cars can cause some pretty strange symptoms, even when they seem to be fine by a load test or conductance test.

-Rod

 

[Ta2dResqr]

Have you checked the voltage at the PCM? A damaged wire could increase resistance and cause a voltage drop. I would hate to see you spend a bunch of money on a PCM and still have the same issue and figure out it was a simple wire. Is the Low Voltage code P0562? What other codes do you have? You stated the A/C issue was intermittent. If the right (wrong) conditions are not met during testing of the battery/alternator, you may have an issue with one of those and not the PCM. Honestly, in all the years of working on cars (professionally and at home) it has only been a PCM/ECM/BCM/TCM issue a handful of times. Generally, there is something else wrong.

 

[Steven Grappy]

I would suggest looking for a bad battery, shorted internal alt, wiring/corrosion problem. In all my years of being a professional mechanic, I have never seen an ECM/PCM go bad intermittently, they are either good or they aren't. The reason it gets worse with the a/c on is from the increased load the a/c is using.

 

[SilvererSHO]

My wife's 2014 SEL HVAC system went haywire a couple of months ago. The heat was stuck on. She stopped by a shop we are using and they didn't have time to do a full diagnostics on it but they unplugged something under the glove box I think to disable the heat for the few days before they could get the car in. When they went to do the diagnostics they unplugged something else and it checked fine. They plugged it back in and it has been working fine ever since. So in the end, it was just a bad connection at the plug connector. Sometimes it's just that simple. As a bonus he earned our trust as a mechanic. She had some other things addressed while it was in so they didn't lose any money wasting time on her car and they didn't try to $crew us over potentially losing a customer. Win win!