I have a 2000 C5 and have noticed these codes (not current but H/History)

B0-RFA (Remote Function Activation)
U1096 - Lost comm w/IPC
U1064 - Lost Comm w/BCM
U1016 - Lost comm w/PCM

Anyone else had these and found they were due to gnds?
(Gnds used for remote ckts listed as G201, G202, G104 IIRC.) - since they're not a constant problem I assume it's wiring/intermittent connection related?
(the remote itself should not be a factor right? I replaced battery about a month ago - after having the battery disconnected recently for about 1 hr, I noticed after reconnecting the battery the first time I tried the remote unlock I had to hit the button twice - but I checked codes soon thereafter - none were present.)
I noticed them today after driving to the store - returned home, unloaded car (popped hatch), drove back out for a short drive, then returned home. Checked codes and found them. (I've seen some history U codes before about a month ago - same numbers but I don't think they were in the RFA section - maybe in the BCM list, can't recall now. I wrote the numbers down but not what module they were under back then.)

G201 and G202 are behind the inside panels (side panels at floorboard area) I think and 104 is near the battery right? (104 is a gnd std at the battery area plastic wall/shield area IIRC) doesn't happen often but I'd like to try and fix it. (what would make the error appear infrequently? if the gnd was bad I'd expect other faults as those gnds are used for other functions I think - could it be the gnd (or some other circuit connection/connector) gets disturbed from say a rough road? (but even then I'd expect other faults)
And since those codes were under RFA (Remote Function Activation) - I assume that means it happened during a remote (fob) command (car sitting still - no shock/impact from road, etc.) - and today I didn't see any problems with the remote unlock (door unlock or popping the trunk).

Unless it's some other connector in the ckt (BCM?) that is intermittent.
just thinking out loud...

wondering if anyone else has seen this sort of thing (and fixed it for good) or have some suggestions - I've had the car only a few months. Not taken those panels off to get to the gnds listed (and check the BCM connections while in there) Thanks.

 

i'ts either your battery or the FOB battery

 

The very first thing that I would do is charge my battery. Make sure it is FULLY CHARGED!
Next , check chassis G-104/108 in the battery compartment:

Follow the small negative battery cable down to the chassis ground stud. G-104/108. That is the PCM and RFA ground.

Remove the grouund eyelet from the stud and clean it with a wire brush.


See if that corrects the issue.

BC

 

I would not be concerned about U codes unless you have some function that is not working. I got U codes for the door lock solenoid problem but they are not that useful.

 

Battery is an almost new Red Top and I always have it on a Battery Tender when in the garage.
And I mentioned the FOB I'm using has a new battery (replaced within the last month)

From the other replies here are those "U" codes (lost comm w/XXX) very very common then? (I know since owning the car I've seen those codes once before - but not under RFA section IIRC)

 

Thanks - I had checked 104 (cleaned it but not wire brushed, tightened it) - is that the same gnd as 108? (108 not in the gnd table/manual copy posted here but I'll check my 00 service manual)

Battery is kept on a battery tender and is relatively new (Red Top).
(Also per schematics I guess I should check the gnds in side the interior floor panel areas - G102 and G202.)

 

Are you having an issue with your key fob or tire sensors???
if not then i wouldnt worry about the u codes

they are not uncommon in the RFA on c5's

and u codes dont have to mean there is an issue

there are more to help a technicain if he has an intermitant problem that is driving him crazy and even then i dont have u codes help me fix a car very offten

the different modules verify communication with each other alot( i cant remember how often)(but i thought it was every couple seconds or a couple times every second, cant remember)

but you get the code when a module doesnt check in correctly or its 2 busy to check in, but the next time it usually does whci is a second or so later

so u codes dont have to mean there is anything wrong with th ecar

 

I have had the same codes since I bought the car, my battery is fine and so are the grounds. Had the car for 2 1/2 years, no problems. Ignore these three codes, you will be fine.

 

As long as the U codes are history, I wouldn't worry too much about them. It is indicating that the module is shutting down or failing to communicate at some point in time, most likely during engine start up.

My 98 had lots of on coms. It was because of the battery and the grounds. My 02 Z has not had any. Woops,,, I'll take that back. Once the door electrical connector shorted out and I had a LDCM NO COMMS until I fixted it.

BC