I recently had problems with a dying battery and having to repeatedly disconnect said battery to recharge it and/or jumpstart the car. I'm worried that something might've gotten fried, so after replacing the battery I went into the hidden DTC menu (the one you can get to with the read+foglight button trick) to check, but I'm not sure what to make of the results.


1) Four modules report DTC errors: DEM, CEM, CCM, PSM. An ODB scan comes up clean. Is there any easy way to get the codes for these errors or figure out whats wrong without throwing a couple hundred bucks at a dealer for a diagnostics test?


2) The TCM, ECM, DDM, PDM, REM, and UEM all say "checking" instead of ready or an error. In particular I'm worried about the DEM/CEM/REM/UEM (the other electronics modules listed in the menu). I heard somewhere that some modules will only report after certain conditions have happened, but after driving around for a couple hours and trying some tests I read, the only module to start reporting was the breaks (BCM). Does anyone know EXACTLY what you're supposed to do to get these to say anything?

 

All of these cars are full of codes. That really doesn't mean anything since they can get set with a low battery and stay there forever.

Your standard OBD II scanner will only read powertrain codes, not other modules. So, you'll need someone who has access and can clear them all out and see which ones return.

 

The CCM and PSM are likely nothing to worry about.

The DEM could be a problem with the AOC pump or temp sensor... You may not have AWD.

If the AOC pump seizes and pops the DEM fuse, there would also be a CEM code for communication with the DEM. However, if the DEM had no power, it wouldn't show a fault, so it is more likely a temp sensor problem. Or an old code due to the low voltages.

Without a more expensive scanner, or VIDA and a DiCE, there is nothinf you can do.