06 monte carlo LTZ with U codes

[Triple-X08]

ok guys, i got a fun one here. friday i had a older lady come in with a 06 monte carlo LTZ. the complaint was that the radio would intermittently shut off at times, it would go completely blank, no sound, no lights, no display, like as if someone unplugged the radio and just had it sitting in there.

anyways, the car has been to another dealer, which will remain nameless at the moment, im not to thrilled with there lack of diagnostics. and the fact that it came to me with an intermittent problem doesnt exactly blow my skirt up either. details i have, the other chevy dealer where the car was purchased from, they installed a new radio. problem still existed after they got done with it. so they recommended her to our dealer.

problem is, i cant get the damn thing to act up. no problems at all. so i checked si found no bulletins for it, checked the BCM and radio for dtc's found a couple u codes in it. with symptom code 00. so i called TAC. they told me to check the usual stuff like power and grounds, and low speed GM LAN lines. so i did, and i found no problems at all. so i had the customer be on there way, and said to bring it back in when they have more time, well yesterday rolls around.

i get the car, and i have the same problem. no problems that i could visibly see, and i still cant duplicate there concern. so i have my manager drive it to see if he can get it to act up, no luck at all. i then checked the vehicle for dtc's i performed the vehicle dtc check on the tech 2, through the vehicle communication interface module. i have 15 dtc's all u codes. all with symptom code 00. all modules that were on the dtc list, were all on the low speed GM LAN line.

i still have not got the vehicle to act up. i checked the LAN line, it is ok at the moment, i can communicate with all modules through the tech 2, they all respond when i ping them. so i have been driving it and idling it and doing anything i can to get it to act up. i dont believe its a problem on the low speed line itself, but i believe its something internal to a module. i say that because i can communicate with them through the tech 2 and no modules have a problem communicating with the tech 2.

i have constructed a harness that plugs in place of splice pack 205, which is the star connector for the GM lan low speed line. so when a module acts up i will disconnect that module from the group and see if the problem still exists.

but still the problem exists, i cant get the car to act up. but when i do, i will figure out whats going on.

also, i have cleared the dtc's and none of them have returned. yet.

judging by the history the new W cars have had with BCM problems, i am willing to believe that that is the problem. i dont want to throw parts at it, and i will not even consider it until i have substantial evidence that a specific part is the cause of the malfunction.

so if anyone has any ideas on this, let me know, im not really familiar with the GM LAN networks, as i dont normally work on them, we dont see many come in for a LAN problem.

[GMCdriver]

I had a customer(an older guy) come in with a similar concern one time, "The radio will just shut off all by itself."
He had it in to our service department and they gave it back to him as "unable to duplicate concern."

I talked with him for a little while and discovered that he didn't understand "retained accessory power." As it turns out, he was stopping in the mall parking lot and sitting in the car while his wife went shopping. He would shut the car off and since the radio was still on he figured that he had the key in the Acc position when in fact he had it off. Our service advisor assumed that the guy was talking about a concern that occured while driving but it was actually a missunderstanding of a vehicle feature that the customer perceived as a defect.

[Triple-X08]

yeah, im not really sure, i wish i could be with the customer when it happens.

[rbarrios]

I dont have any input- except my story.
Yesterday- 07 Impala.
Remote start the vehicle.
I go to get in- as im getting in- I hear 3 quick clicks (similar to what my old add-on car alarm would do when the lights were flashed by the alarms module)...
Never heard that before... hmmm. I even wondered--- did my lights just flash?
I insert key- turn key- AC blowers stops- (feature of remote start).
I begin to backup- and drive....
I look at clock--- NO clock visible on radio... odd
I try to turn on radio--- radio does not power on.
I go make a turn-- turn lights blink- but no blinker sounds......
I stop and get out to make sure my blinkers blink externally--- they do....
I hit the onstar and phone button---- no sound. But the onstar LED is green.
I shut off car- and restart.... still no audio/radio.
when I get to my destination- I take out manual find the fuse #... pop the hood and remove the fuse for 30 seconds.
Get back in the car- and I now have time. restart car- I now have radio, onstar, phone, and blinker sounds.
I dont know if the clicking sound came from the speakers or dash....

I figure that the radio ran into some LAN communications problem when it was doing its thing and required a reboot/reset by removing power......
Your post reminded me of my scenario yesterday.
the impala has not had any problems and never been back to dealer for any problems.
we are about to hit 20,000.
I sort of figured it was a problem that I can only describe as you running windows- and you have something running and then click on something else- and something else- and the system either bogs down- or it suddenly locks up on you.
I dont know-- maybe just a communications problem via that LAN?????
Just guessing on my part.

[scooter10572]

Originally Posted by Triple-X08

ok guys, i got a fun one here. friday i had a older lady come in with a 06 monte carlo LTZ. the complaint was that the radio would intermittently shut off at times, it would go completely blank, no sound, no lights, no display, like as if someone unplugged the radio and just had it sitting in there.

anyways, the car has been to another dealer, which will remain nameless at the moment, im not to thrilled with there lack of diagnostics. and the fact that it came to me with an intermittent problem doesnt exactly blow my skirt up either. details i have, the other chevy dealer where the car was purchased from, they installed a new radio. problem still existed after they got done with it. so they recommended her to our dealer.

problem is, i cant get the damn thing to act up. no problems at all. so i checked si found no bulletins for it, checked the BCM and radio for dtc's found a couple u codes in it. with symptom code 00. so i called TAC. they told me to check the usual stuff like power and grounds, and low speed GM LAN lines. so i did, and i found no problems at all. so i had the customer be on there way, and said to bring it back in when they have more time, well yesterday rolls around.

i get the car, and i have the same problem. no problems that i could visibly see, and i still cant duplicate there concern. so i have my manager drive it to see if he can get it to act up, no luck at all. i then checked the vehicle for dtc's i performed the vehicle dtc check on the tech 2, through the vehicle communication interface module. i have 15 dtc's all u codes. all with symptom code 00. all modules that were on the dtc list, were all on the low speed GM LAN line.

i still have not got the vehicle to act up. i checked the LAN line, it is ok at the moment, i can communicate with all modules through the tech 2, they all respond when i ping them. so i have been driving it and idling it and doing anything i can to get it to act up. i dont believe its a problem on the low speed line itself, but i believe its something internal to a module. i say that because i can communicate with them through the tech 2 and no modules have a problem communicating with the tech 2.

i have constructed a harness that plugs in place of splice pack 205, which is the star connector for the GM lan low speed line. so when a module acts up i will disconnect that module from the group and see if the problem still exists.

but still the problem exists, i cant get the car to act up. but when i do, i will figure out whats going on.

also, i have cleared the dtc's and none of them have returned. yet.

judging by the history the new W cars have had with BCM problems, i am willing to believe that that is the problem. i dont want to throw parts at it, and i will not even consider it until i have substantial evidence that a specific part is the cause of the malfunction.

so if anyone has any ideas on this, let me know, im not really familiar with the GM LAN networks, as i dont normally work on them, we dont see many come in for a LAN problem.

Just remember class 2 and lan are about opposite.if you have a class2 module shorting and unplug system is fine,lan is a looped circuit with terminating resistors to boot so the unplugging definitely does not work,ever think of putting in the vdr and seeing if cust can get a snapshot?

[Triple-X08]

i couldnt get the car to act up today, just put it all back together, service manager said to put it back together there is nothing we can do.

possible my u codes could have been caused by something different. possibly a dead battery or something at one point.

i dont know, never ran into a problem like this.

had a couple nice ones today, both involving stop lamps, one on a trailblazer and the other on a colorado.

trailblazer no lights worked, not even the chmsl. ended up being a stop lamp switch.

colorado both stop lamps in the rear were inop, but the chmsl worked. checked wiring had 12 volts at the rear body harness, but no power at the sockets, both sockets melted, replaced both rear socket assemblies, nice because they come in a complete setup, with harness from the rear body connector to the tail lamp assembly equipped with lights and even the tail light housing itself. so just bolt and plug and play.

[TRWRacing]

On my 06 MC once I started the car and the radio did not work, DIC did not woark. Turned the car off and started it again same thing. Drove the car 10 min. Turned it off and the radio and DIC returned to normal. It has not occurred again. This was a year ago.