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      01-23-2022, 08:55 AM   #23
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Kind of stating the obvious here, once you guys are able to find wire colors and pin locations, you might be able to do the old fashioned work of using a multimeter to see if you have power and where. I.e. does the seat get power but not get warm (issue in the seat), does the seat not get power from an ECU type module (ECU being dumb / busted), does the switch itself maybe not actually work properly, is a wire powered but only part way indicating a break in it. And so on.

My seats seem to work but I've been following along and hope you get it sorted out!
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      01-23-2022, 11:05 AM   #24
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Hey tracer. Yeah I checked a couple of places with the multimeter, the power to the passenger seat module and to both of the rear seat switches and they have power to them.

I'm not sure if a multimeter works to check the LIN_BUS (yellow coloured wire) with a Multimeter. From what I see on the internet you need some special analytical tool to properly check the LIN_BUS?.

I attached photos of the rear seat switches, passenger seat and AUC Sensor that I checked and put an arrow to the LIN_BUS wire (Yellow) Ė thatís according to the previous photos.

I also put this link that gives a simple breakdown of the LIN_BUS and CAN_BUS Ė (simple Ė yeah right Ė hahah). But seeing that there is a Master and a Slave confuses me more and maybe there is an issue with the Slave and thus that row of components donít work? Iím not sure which part is the Slave on this line Ė if there is even one.

https://www.csselectronics.com/pages...l-intro-basics

.... and again I'm really just trying to trouble shoot with a very very limited knowledge (okay none) on LIN_BUS and CAN_Bus so if anyone knows that stuff please HELP!!! haha
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      01-23-2022, 02:00 PM   #25
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Quote:
Originally Posted by Deano58_BMWX3 View Post
Hey tracer. Yeah I checked a couple of places with the multimeter, the power to the passenger seat module and to both of the rear seat switches and they have power to them.

I'm not sure if a multimeter works to check the LIN_BUS (yellow coloured wire) with a Multimeter. From what I see on the internet you need some special analytical tool to properly check the LIN_BUS?.

I attached photos of the rear seat switches, passenger seat and AUC Sensor that I checked and put an arrow to the LIN_BUS wire (Yellow) Ė thatís according to the previous photos.

I also put this link that gives a simple breakdown of the LIN_BUS and CAN_BUS Ė (simple Ė yeah right Ė hahah). But seeing that there is a Master and a Slave confuses me more and maybe there is an issue with the Slave and thus that row of components donít work? Iím not sure which part is the Slave on this line Ė if there is even one.

https://www.csselectronics.com/pages...l-intro-basics

.... and again I'm really just trying to trouble shoot with a very very limited knowledge (okay none) on LIN_BUS and CAN_Bus so if anyone knows that stuff please HELP!!! haha
Hey Deano, check out my earlier post about a quick check you can do for the LIN bus using a multimeter. On the X3 it will be the JBE that is the master (there is only ever one master on a LIN bus) and all the other components are the slave devices. The way I think about the LIN bus is like a classroom where the teacher has to call on the students to get their answer. The LIN master calls out the name of a device, then that device sends back its information. Then the LIN master calls out the name of the next device and that device sends out its info and on and on in a loop. So if the master isn't talking, you will see the bus stuck at 12v (or something like that near battery voltage) because the students won't say anything unless they're called on. If you read 0v, then that means the point where you're measuring doesn't have any master OR slave connected to it, check that the line you measuring is actually connected to the rest of the bus, or that the devices have power. If you measure something between 0 and 12 then that means communication is happening which means the master and at least one slave are working. It doesn't tell you that they're all working, for that you'd need a LIN sniffer.
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      01-24-2022, 08:04 AM   #26
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Thanks Jonmon, that’s awesome and language I can understand – haha. Makes a lot of sense now. I’ll check the LIN_BUS lines on some of the modules (Slaves) this week and see what the readings are.

One question – would you know if it’s possible for the JBE to lose it’s coding for all of the 7 slaves on that line? Or would that be highly unlikely or impossible.
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      01-24-2022, 03:38 PM   #27
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Quote:
Originally Posted by Deano58_BMWX3 View Post
Thanks Jonmon, thatís awesome and language I can understand Ė haha. Makes a lot of sense now. Iíll check the LIN_BUS lines on some of the modules (Slaves) this week and see what the readings are.

One question Ė would you know if itís possible for the JBE to lose itís coding for all of the 7 slaves on that line? Or would that be highly unlikely or impossible.
Typically no, at least in general for CAN/LIN buses (I'm an integration engineer at another German OEM that uses basically all the same tech as BMW), but something like what you're describing is defined in software so they (BMW engineers) could certainly have decided that was a fail safe condition they wanted... But I'm no expert on interpretting the fault codes from these vehicles, maybe a local (preferrably independant) BMW shop near you can give you some extra clues if you come to a dead end.
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      01-24-2022, 05:27 PM   #28
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SOLVED! There are three seat heat modules, one under each of the seats that have no heat: right front and both rear. They are all the same, BMW part number 61-35-7-490-465 Control Module. My dealer (Sandia in ABQ) suggested that I take my shiny new module and try it under EACH of the three seats, one at a time. Sure enough, like a series-wired light circuit, if one fails, the whole string goes down. On my third attempt (right rear), the whole system came alive and all works normally. So get a new module and try it under each seat until you hit on the correct one. (Hopefully only one of three is bad, as was my case!) They are easy to get and remove with no tools.
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      01-24-2022, 07:13 PM   #29
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WOW! That’s awesome Mineral!! I’m going to order one right away! Thanks for getting to the bottom of this!
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      01-24-2022, 10:24 PM   #30
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Quote:
Originally Posted by mineralfarmer View Post
SOLVED! There are three seat heat modules, one under each of the seats that have no heat: right front and both rear. They are all the same, BMW part number 61-35-7-490-465 Control Module. My dealer (Sandia in ABQ) suggested that I take my shiny new module and try it under EACH of the three seats, one at a time. Sure enough, like a series-wired light circuit, if one fails, the whole string goes down. On my third attempt (right rear), the whole system came alive and all works normally. So get a new module and try it under each seat until you hit on the correct one. (Hopefully only one of three is bad, as was my case!) They are easy to get and remove with no tools.
Cool! That's really an interesting way that it fails, seems like the bad part was taking down the lin bus. Just curious, you say once you replaced the right reat they all worked, but I'm wondering if simply unplugging the bad one would be enough to make the others start working. Did you happen to try that?
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      01-25-2022, 07:31 AM   #31
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Good point, I'm going remove my rear seats today and give that a try.
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      01-25-2022, 08:34 AM   #32
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Quote:
Originally Posted by mineralfarmer View Post
SOLVED! There are three seat heat modules, one under each of the seats that have no heat: right front and both rear. They are all the same, BMW part number 61-35-7-490-465 Control Module. My dealer (Sandia in ABQ) suggested that I take my shiny new module and try it under EACH of the three seats, one at a time. Sure enough, like a series-wired light circuit, if one fails, the whole string goes down. On my third attempt (right rear), the whole system came alive and all works normally. So get a new module and try it under each seat until you hit on the correct one. (Hopefully only one of three is bad, as was my case!) They are easy to get and remove with no tools.
Dang, you have to go from Ouray to Albuquerque for service? How big of a pain is that?
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      01-25-2022, 05:17 PM   #33
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Quote:
Originally Posted by jonmon6691 View Post
Cool! That's really an interesting way that it fails, seems like the bad part was taking down the lin bus. Just curious, you say once you replaced the right reat they all worked, but I'm wondering if simply unplugging the bad one would be enough to make the others start working. Did you happen to try that?
No, sorry, I did not.

Last edited by mineralfarmer; 01-25-2022 at 05:26 PM..
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      01-25-2022, 05:18 PM   #34
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Originally Posted by Opie55 View Post
Dang, you have to go from Ouray to Albuquerque for service? How big of a pain is that?
That's why I do all my own work!
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      01-31-2022, 11:17 AM   #35
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Absolutely great timing on this, as this just happened to me this weekend. Wifey not happy I was the only one to have heat at 22 degrees F - though I did ask if she wated to dive, as only the driver seat heat is working! It was not convincing enough an argument though...
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      02-01-2022, 03:42 PM   #36
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You were right jonmom

Hey Jonmon, just got a chance to take a look at my modules and you were right!!! I unplugged my right rear seat module and both rear heated seat lights went on and the left rear and right front heated seats began to work.

So it looks like the right rear module was the problem and just like you thought, when the bad module was unplugged, it solved the issues for the other heated seats and AUC sensor. I hooked up the Diagnostic Scanner and now the 7 codes cleared and it only shows the R.R. seat as an error.

Probably wonít pay the $550.00 CAD for a new module, Iíll just have the family members I donít like sit in that rear seat in the winter. - hahah

Iíve attached some photos of the connection that I unplugged at the module. I see Lurcher has the same problem so this might help him and more importantly his wife Ė hahaha.

Thanks again to Jonmom and Mineralfarmer for solving the problem if it wasnít for you guys Iíd still be in search of that illusive X227Ē1V junction. I was obsessed. Hahah. Anyway I owe you guys a beer!!!!
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      02-01-2022, 09:53 PM   #37
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Quote:
Originally Posted by Deano58_BMWX3 View Post
Hey Jonmon, just got a chance to take a look at my modules and you were right!!! I unplugged my right rear seat module and both rear heated seat lights went on and the left rear and right front heated seats began to work.

So it looks like the right rear module was the problem and just like you thought, when the bad module was unplugged, it solved the issues for the other heated seats and AUC sensor. I hooked up the Diagnostic Scanner and now the 7 codes cleared and it only shows the R.R. seat as an error.

Probably wonít pay the $550.00 CAD for a new module, Iíll just have the family members I donít like sit in that rear seat in the winter. - hahah

Iíve attached some photos of the connection that I unplugged at the module. I see Lurcher has the same problem so this might help him and more importantly his wife Ė hahaha.

Thanks again to Jonmom and Mineralfarmer for solving the problem if it wasnít for you guys Iíd still be in search of that illusive X227Ē1V junction. I was obsessed. Hahah. Anyway I owe you guys a beer!!!!
Awesome! I googled the part number from the photo 921646802, and it looks like used parts are in the $20-50 range if you ever want to try and fix it for a bit less. Having something like that not working on my car always nags at me
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      02-02-2022, 06:06 PM   #38
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I might do that. I called our local bmw dealer last week after mineralfarmer showed the part number 61-35-7-490-465 for the Control Module and that one is $550 here so the backseat ones may be cheaper. I’ll do some checking on line too. Thanks again.
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      02-15-2022, 09:10 AM   #39
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Just replaced mine - left rear. Of course I started with front right , then rear right....

For those who don't know - rear seat, bottom cushon, just pulls up from the front lip of the cushon. Modules on the left and right side attached underneath. 3 cable bundles in pic above, just use your nail and push tab down and pull out. Module has a snap fitting you just pull out to release.

Paid ~$300 US for module. ~20 min to fix. Just replace one , crank car, try to tun rear seat on. Get a light - found the bad one - if not, try again!
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