Hey guys! So my problem started after I went to go fill up on gas, the pump was acting a bit weird but still filled the tank. As I was getting home I decided to back into my spot and that's when the cluster went crazy. The problem only starts when it is in reverse and then goes back to normal after. The CEL light turned on giving me codes U0164 and P0463 and now my airbag light flashes, and my "manual mode" won't work. Other than that the car drives just fine so it seems to be a weird electrical issue. I'm completely lost on what it could be but maybe someone on here has had a similar issue? I'll probably take her into the shop tomorrow to see if they can find anything. Will post updates Anything helps!

 

Sounds like your Unified Meter AC Amplifier kicked the bucket. Becoming a more common issue on these cars as they age. As to why it only acts up when you put the car in REVERSE is beyond me. Given the U0164 code, I would start looking for a replacement. It is best to get the part number off of the module that is installed in your car. This will ensure compatibility and retain all features/ functions specific to your car. See this post as it will show you what the module looks like and where it is.

That said, the Unified Meter/ AC Amplifier part number will be 27760-xxxxx. The last 5-digits will be specific to your car.

 

@ILM-NC G37S what is the purpose of a unified meter ac amplifier? This is the first time I’ve heard this term used and am curious.

 

The Unified Meter & AC Amplifier serves two (2) main purposes.

First, for the Unified Meter "portion," per the FSM, "Receives information required by the combination meter from various units via CAN communication line and transmits it to the combination meter with communication line." Items like vehicle speed, engine RPM, fuel/temp, as well as the MPG and other items in the center LCD screen (between the analog gauges) all receive their inputs from the amp.

Second, the AC Amplifier "portion." That is self-explanatory. This is the main module that controls every aspect of the automatic climate control system. It handles temperature, air direction, blower speed, as well as dual zone control, sun load, compressor cycle control, and refrigerant metering. It also handles the "self-diagnostic" protocol for testing the AC system- though that alone is not the easiest to figure out.

The amp is also the unit that handles the paddle shifters. Both the UP and DOWN shift signals get processed through the amp to the TCU. Push-to-start, iKey functions, and a ton of other systems rely on the amp.

Important to note that newer Q models (like the Q60) "divorce" the amp. The gauge cluster contains the "Unified Meter" portion- receiving/ transmitting information directly via the CANBUS. Even the paddle shifters go through the cluster. Whereas the HVAC has its own dedicated AC amplifier as a standalone.

Hope this helps...

 

Ok. This is an excellent explanation. "AC" landing in my brain as "Alternating Current" initially, which set me off down the wrong path. So it seems that the Unified Meter portion is a sensor hub that monitors various inputs over the CAN bus, while the AC Amplifier is dedicated to the HVAC control system. How many of these have you seen go bad? How hard are they to replace?

Is this the unit?
https://www.ebay.com/itm/15564663033...RoCZoIQAvD_BwE

 

If I were to guess I would say about a dozen or so have failed as reported here on the forum and most of those failures are related to the P0460/1/2/3/4 fuel-level errors. Some members have found the culprit to be a failed solder joint on one of the resistors. However, in OP's case with the U0164 (CANBUS error/ amp) code, more than likely the amp is shot.

Replacement is easy- a 1-hr. job give or take as long as one pays attention to the wiring connectors! There are two (2) identical connectors that plug into the AV control unit and too many folks have plugged the wrong connectors into the wrong slots. If the amp is not plugged in correctly, it will brick the car until properly connected.

The amp is the plastic white box attached to the AV headunit. As I mentioned above, it is best to get the part number off of the module that is installed in your car. This will ensure compatibility and retain all features/ functions specific to your car. See this post as it will show you what the module looks like and where it is.

That said, the Unified Meter/ AC Amplifier part number will be 27760-xxxxx. The last 5-digits will be specific to your car.