SL/R230: How do you disable the GPS to set the clock?
02-21-2019, 08:10 AM
#1
Senior Member
Thread Starter
How do you disable the GPS to set the clock?
The clock is 5 minutes behind. It is synchronized with the head unit therefore the head unit is 5 minutes off. I read in this forum that minutes can be adjusted if the GPS is not present. How can I disable the GPS with or without DAS?
02-21-2019, 09:32 AM
#3
Senior Member
Thread Starter
I had this for weeks. I drove the car outside and checked the number of satellites and i had 7-8. Yet the time is still 5 minutes behind compared to my iPhone.
02-21-2019, 10:01 PM
#4
MBworld Guru
You have to use SDS to code the instrument cluster for "COMAND = NOT PRESENT". YOu will then have full clock setting on the MFD. However, you will lose NAV display in the MFD. Note that there is a bug in the NAV system where the clock will be way off. It has to do with a limitation of the way it counts weeks and rolls over. It's been discussed in other forums for other models. It's sort of liek a Y2K bug, and it's not going to be fixed, so the coding is the only way to fix it.
02-22-2019, 02:17 AM
#5
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2005 R 230 SL350 (M112 3.7). Sold the 1966 W113 230SL recently
Funny little blunder, MB... so how is it that my clock is accurate? Has there been a series of Comands with blunder inclusive software?
02-22-2019, 08:49 AM
#6
Senior Member
Thread Starter
Thank you Rodney, I am not sure if de-synchronizing the clock from the head unit in MFD will allow me to set the clock. Another way would be to disconnect the battery at 11:59 for 1 minute although I fear it would go back the moment it receive satellites.
02-22-2019, 11:20 AM
#7
MBworld Guru
If you code the cluster so that NAV is not present, it opens a menu in the cluster for manual setting of the clock using the menus in the cluster. I don't think it will correct the time shown on the NAV unit itself, but it will allow the time on the dash clock to be set.
It is a programming bug, and it's due to the way the GPS system works There's a lot going on with it and it's a bit hard to explain. First of all, it involves Einstein's Theory of General Relativity:
http://www.astronomy.ohio-state.edu/...Unit5/gps.html
So, all NAV systems have to correct for that. It's just 38 microseconds per day, but it adds up over time, and if the NAV systems has bugs in it that cause it to miscalculate the date, it can cause problems with the time Another factor is leap year. Leap years are actually not corrected by an extra day every 4 years. It;s slightly less than that
To make all this work, your NAV system needs to know exactly what the date it. The problem is, the GPS satellites do not transmit a date. The transmit a week number, that started in January 1980. BUt that week is a 10-bit valu, so it rolls over every 10,204 week. See here:
https://www.gps-repeaters.com/blog/g...pril-6th-2019/
So, just like "Y2K" when computers used two-digit years and needed to understand that when 12/31/99 rolled over to 01/01/00 should mean "01/01/2000" and not "01/01/1900", the NAV unit needs to understand that Week 0 is Actually April 7, 2019 and not August 21, 1999.
But you say, "It's not April 7, 2019 yet!" Well, apparently, whoever coded the GPS for your COMAND unit didn't use that date range. They started with a different date. They probably thought they were going to be "smart" and use some other algorithm to correct for the week rollover, and guess what? It didn't work! I think these started failing in November of 2018. Theoretically, MBZ could create a firmware update to fix it, but they have not done so and apparently have no plans for it. Their take is that the affects cars are now over 10 years old, so why bother?
It is a programming bug, and it's due to the way the GPS system works There's a lot going on with it and it's a bit hard to explain. First of all, it involves Einstein's Theory of General Relativity:
http://www.astronomy.ohio-state.edu/...Unit5/gps.html
So, all NAV systems have to correct for that. It's just 38 microseconds per day, but it adds up over time, and if the NAV systems has bugs in it that cause it to miscalculate the date, it can cause problems with the time Another factor is leap year. Leap years are actually not corrected by an extra day every 4 years. It;s slightly less than that
To make all this work, your NAV system needs to know exactly what the date it. The problem is, the GPS satellites do not transmit a date. The transmit a week number, that started in January 1980. BUt that week is a 10-bit valu, so it rolls over every 10,204 week. See here:
https://www.gps-repeaters.com/blog/g...pril-6th-2019/
So, just like "Y2K" when computers used two-digit years and needed to understand that when 12/31/99 rolled over to 01/01/00 should mean "01/01/2000" and not "01/01/1900", the NAV unit needs to understand that Week 0 is Actually April 7, 2019 and not August 21, 1999.
But you say, "It's not April 7, 2019 yet!" Well, apparently, whoever coded the GPS for your COMAND unit didn't use that date range. They started with a different date. They probably thought they were going to be "smart" and use some other algorithm to correct for the week rollover, and guess what? It didn't work! I think these started failing in November of 2018. Theoretically, MBZ could create a firmware update to fix it, but they have not done so and apparently have no plans for it. Their take is that the affects cars are now over 10 years old, so why bother?
