robertfa

Unfortunately, The Nav Radio unit doesn't get it's time info from any of the other car's systems. It gets its time from its own GPS receiver which, is working just fine. GPS will not determine location without precise time data (down to the nanosecond). Somehow, the part of the unit that coverts GPS time data to a conventional time/date display is not working. My post 691:

"I believe the clock in our nav radios continues to free-run when GPS signals are not available (probably also so long as the car battery is connected). I believe when anyone with this vintage of nav radio disconnected power and re-connected power it looks for time and date translated from the GPS time which it is *failing to provide. I'm amazed that it is not designed to allow the clock to free run all the time if it's not being synced to GPS. I think the firmware (or software) flaw is more like post#656 (also see my post#674) incorrect data conversion. In any previous post reporting the clock problem, most, if not all people on this list have noted that the navigation is still working, map displaying the correct location. I've experienced that the navigation has worked OK all of this time on my nav radio as well. If the GPS receiver is functioning correctly, displaying accurate location, it must be receiving all satellite data (including time) and it must be syncing to GPS system time. If it does not have precise time it will not calculate a location. *My theory (and I'm not a GPS expert but do have an engineering background) is the problem is down stream from the GPS receiver where time data is converted to conventional time and date for display. Also, from what I've seen, latitude and longitude as well as time are not displayed or falsely displayed on the diagnostic GPS page (see post#622) yet the receiver must have lat and long and correct time in order to determine valid location".

It would be great if 50 re-starts would clear the problem but, I'm sure most of us have re-started at least 50 times in the last four months (especially daily drivers).

vintagegas

Thank You for that great explanation.

harryjam

Yesterday I’m cleaning of my 2007 C6. I leave it in acc mode overnight.This morning in need a Jump. Got the Jump. Back out the garage. CLOCK was Working.All i did was jump it . Both cables on both batteries . Clock was working. ITs been out about a month, after i was cleaning the post. Bad news ,the year was 2000,but i have a clock now.

robertfa

Interesting, sounds very similar to others. If you go into the diagnostic mode, nav page (post#610), does it show running GMT time and active latitude/longitude?

harryjam

ITS showing everything. )GPS time and position . I guess it’s right. Right now I’m happy. Give it 24 hours

harryjam

GPS still has a line thru it . Every time I cut the car off the clock stops. So really is not working. But I see a clock. That’s working when the car is running. GPS is working

robertfa

The line thru 'GPS' might take more than a few minutes (maybe 20 or 30) especially after power disconnection as the Nav unit probably needs to re-acquire the Almanac (what I understand is a 'cold start'). The Almanac is the data the receiver gets that tells where the satellites are supposed to be and when. Just because there is a line thru 'GPS' doesn't necessarily mean no GPS data is received at all.

Troy

I contacted BBB not because they would solve the problem but I knew they would definitely let an office higher in Chevrolet than Engineering know there was a complaint and problem. The net result is I know for sure GM is aware of the problem and, more importantly, they are working on it.

harryjam

Well my clock has been working now for over 36 hours now. Time and everything is correct. Haven’t checked the year yet. Yesterday it was showing January 2001. Also the clock would stop when the car was off . Today it’s correct no problem.

96LT1coupe

i have a 2010 LT3 grand sport recently out of winter storage and have the same situation here Everything functions after window index procedure although clock display is blank and will not accept input to set.

harryjam

After i gave myself a jump yesterday.Clock started working . Today no problems . Clock kept correct time all day today. Yesterday the clock was acting up today no problems. Tomorrow is another day ‘I’ll see what happens.

Vette core

PIT5652 dated 1/18/19 - Clock Shows Dashes And Cannot Be Set After Battery Disconnect
Page 1 identifies 12 brands of impacted Chevrolet cars and trucks with associated production years
ADDITIONAL OPTIONS (RPO): U3R, U3U, U3Z, USR, UUK, UUL, UVB, YQ4
CONDITION: A customer may comment that after the vehicle battery was disconnected or replaced that the clock no longer displays on the radio, or displays dashes. The technician may also find that the clock cannot be set through the radio menu.
CAUSE: Engineering is currently investigating the cause of the concern,
CORRECTION: Please follow the latest version of PIT3830 before continuing with this PI.
CUSTOMER INFORMATION: Please communicate to the customer that we apologize for this inconvenience and that General Motorsis currently evaluating this concern. This PI will be updated with additional details as they become available.

Chevy = Customer service: 1 (800) 222-1020 , 1-866-694-6546
Ask for an American!!! Don't settle for less! IMHO! Ask for a Case #. Mines fixed but I will bitch again about my OE Nav head sitting on the counter! LOL

compyelc4

I jumped my '07 today to see if clock would magically return. It did not.

harryjam

My battery was DEAD. I had to use the key to open the trunk to open the door. I had to get cables .So it was dead about 5 minutes. I was driving and just looked down and saw the clock running.Today I’ll see what year I’m in.

leres

Looks like your car is a 2007? What part number is your radio? You can find it on the hidden diagnostic "software information" page. On the 2013 nav radio in my car both EMP and BMP say 0020856087 which is the 2011-2013 that we know doesn't suffer from the problem.

Online parts houses list 20906715 as the non-export part number for 2007-2010 and I'm guessing that's the one with the broken firmware. My 2007 came with 15791220 so I'm guessing again that was the 2005-2007 part and at some point in production they switched from 15791220 to 20856087.

What I'm wondering is if only the 20856087 has the problem. I don't know if my old 15791220 has it or not, I didn't know about this problem when I swapped radios a few weeks ago. I'm working on getting it running on the bench so I can see...

leres

On second thought another explanation is that although your battery was "dead" it still had enough voltage to keep the volatile memory in your nav unit up. (I remember they used to make a gadget where you could hook a 9V battery up to the cigarette lighter port to keep radio presets from going away.)

Mr.Fixzit

Disconnected my battery yesterday for about 15 minutes. Reconnected, reset windows etc, still no clock. Drove 3 times yesterday (3 restarts) and still no clock. Everything else continues to work correctly.

harryjam

My clock is still working. GPS is working. The year on my GPS is 1/3/2001 . Other than that everything is fine.

compyelc4

But his clock was already toast before he left ACC on and killed battery. After jump it was fresh bread.

FatsWaller

Just musing out loud here, and I can't go back and read through all the posts, so maybe this has already been said. When was the first instance of this problem reported? If we go with April 08 as the date when the GPS week number goes from 1023 to 0, and go back to Oct 15, 2018, then if I did the math correctly, the GPS week number would have been 999. I've seen some pretty incompetent programmers in my time, and the kludges they come up with boggle the mind. If for some reason they were converting the week number and using a 3 digit field to store the value, there would have been a problem when the week number became 1000. Then the problems might have started occurring on Oct 22, especially if they were storing some reference point in volatile memory. Remove power, and the volatile memory contents are lost, and on startup, the NAV unit can't correctly compute the date and display time. There's no doubt that the NAV systems must still be receiving and parsing the GPS signals, otherwise they wouldn't function at all. To me, it's more of a problem in converting and displaying the Date / Time from the GPS signals.