My problems started with the factory radio dying. This weekend I upgraded to a double-DIN head unit and installed some spec-D headlights. I did disconnect the battery in the process so I could run a new dedicated unswitched power lead to the head unit. Plugged the new harness in to make sure the new head unit was working, and all seemed good, so I put the dash back together. Didn't notice anything major at first, but the the next day I realized the temp selector doesn't change, always hot, and the vent adjustment **** isn't responding. Also, the AC won't turn on when I push the button. However the blower selector, rear defrost and recirc all still work.

Then I started noticing the remote lock/unlock started getting quirky, would unlock the driver door but passenger wouldn't unlock no matter how many times I pushed the button, and the lights wouldn't always flash. The next day I got all three brake warning lights as soon as I started it up, but by lunch no more warning lights. This was intermittent for the next couple days. Then this morning I went to go warm it up and all the gauges were dead, so I restarted it, and no change. I went back inside & collected my stuff for work and came back out a few minutes later and the gauges were functioning again, but I also had the CEL on. Went back in & collected my OBDII scanner and drove to work. Once I got there I scanned it resulting in the following codes:

P110F - Ambient Air Temp Sensor Faulty CAN signal
P1551 - External Engine Off Timer Plausibility

Wrote those down and then erased the codes, fired it back up and the CEL was gone, no brake error codes, but still no change in the HVAC controls. Shut it down and noticed it locked correctly and the lights flashed. So some improvement just by resetting the codes. We'll see if any of these gremlins come back. However the HVAC problems remain. I've been doing a lot searching for issues & wondering if some of these issues could be the result of a erratic FRM or possibly the CAS module? It seems like most of the problems I have read about the FRM have to do with moisture from convertible or sunroof cars, but mine is a slick top and my carpets aren't wet, but who knows.

I did have a bit of a challenging time reconnecting one of the connectors to the back of the HVAC control module (the one immediately behind the temp selector wheel), I did my best to reinstall it straight but it didn't want to go in far enough for the lever to swing and lock it back into place, I did finally get it, but it fought me for a bit. At the time I just figured it was an older piece of plastic that was just a little fouled with dust. I was pretty careful with it, but I'm wondering if I either bent over a few pins or something, and I also remember that there were two different connectors with the swing-arm locking mechanism on them, and I'm wondering now if it's possible to mix them up, or will they only fit in their designated slot?

I'm planning on tearing back into the dash again this weekend and re-inspecting the connectors, but it's a bit of a time consuming task & not really looking forward to it, so I'm wondering if there could be some other reasonable things to check out first since I had a few other electrical gremlins that appear to have resolved.

TIA

Jesse
'09 R56 JCW

 

Well, I had dead gauges again this morning, but they came back to life in a few minutes.

 

Just had another thought, does anyone have any information of the pinouts in the engine bay fuse box? Specifically the pins that look like they are for a diagnostic port located next to FL6 and R1 in the area that the map on the underside of the cover identifies as "spares" which is silly because you can't store spare fuses there...

When I installed my Spec-D headlights, I was looking for a switched 12V source to use the halo portions of the lights as daytime running lights. I popped open the fuse box and used a multi-meter to find an un-used switched 12v source and several of those pins seemed like a convenient and innocuous source. I've unplugged it for now to see if this makes any difference, but I'm nervous that my "convenient 12v source" might not have been such a good idea...

 

HVAC issues resolved by removing the center panel and re-connected HVAC plugs.

Issues with dead gauges and only driver's door unlocking remain when vehicle is parked overnight remain. Everything operates normally if started recently.