All,

After a few months of moving, and just getting busy I finally got to the car this weekend to try and find out the root cause for my Christmas tree of lights.
I knew from reading countless posts that it could be so many things and now I'm sort of leaning toward a faulty VTG, but am reaching out for smarter heads then me.

EDIT: Heres my car info:
2008 BMW 535Xi with N54. 144,000 miles, Nothing aftermarket. 90AH AGM batt registered (new). On a battery charger/tender all the time.

Here is what I've done so far:
- In INPA I reset all codes, same in ISTA, the same S0204 Error came back (No comms with Transfer box), sometimes it throws a few DSC comm errors but they are related with the VTG
- The previous owner put a new batt in but it was a lower AMP/hour (80), and it ran like that for a few months with the lights on. Finally a new 95Amp/hour AGM went in, and I coded the new type and registered it (verified in INPA)
- Read the wheel sensors, all checked good, showed speeds, and the SZL showed good steering angles without any errors.
- I was able to get under the passenger seat, and looked at the VTG box and saw nothing, no water issues, no wiring issues, but didn't check actual ohms or voltages.
- No moister near the battery at all, and all of the listed 4x4 fuses look good. There was a weird thing where the 50amp was missing from F1 which was for ABS so I replaced that but still nothing.
- Took the time to learn and update the ECUs for the DME, DSC, and the EGS, simply because I wanted too and they are all original software. When I updated the DME the lights would go out but then came back after.
- I can't seem to clear the lights themselves ever, tried the battery unplug with fuses and ISTA, but they never go out.

So, now I'm looking for some help. Is the VTG box bad? Is an ohm test on the wiring easy to do? Did the shitty battery maybe fry something? Or am I just looking in the wrong place? Could the actual transfer box have a problem (the car drives PERFECT)

Thanks all. (BTW the no CID comms is most likely because I added a CARPLAY display that works excellent, and my RDC is probably from faulty wheel sensors)


only interested in the Transfer box error

VTG is always red

 

Also just curious if anyone has heard of a throttle body harness being the culprit? I read on another forum someone said it fixed it for them but I don’t understand how that would have any thing to do with the transfer case.

 

I've never heard of a TB causing the issue you're having but bad wiring can cause crazy issues. I would check out the connections and wiring them do a module swap. The battery is a mute point. Had you went through troubleshooting through ISTA to see what it recommends

 

thanks for the reply!
so in Ista it only came up with a super generic “loss of comms” troubleshoot, nothing directly for the VTG, so I guess I might need to look deeper and see if it has something like that.
when yo I say module swap, do you mean get another VTG box and see what happens? I see some on eBay for around $100.

 

In ISTA you should be able to highlight the error and calculate test plan. Have you went through the test plan to troubleshoot? Yes I do mean replace the module.

 

yeah hopefully today o can see if I can get it to give me something better, but when I highlighted and calculated a test plan it was a super generic one for just the can bus and not like for the actual VTG, so maybe I can try and find one in the system for it.

 

Ok so that means it was going to test the connection and if that was good it should of said to replace module

 

copy. I will run the tests and report everything back.

 

After running tests in INPA with the module plugged in and unplugged, it would seem the module is bad. I also checked the voltages for terminal 30 (supply) and 15 (wake up) at the plug that goes into the VTG controller and both showed 12.5-13.2 V while the car was running.

Am I missing anything?
Will I need to do anything special if I do order a new module? Code it?

 

Just making sure you're getting new versus a used one.

If new then you would calculate plan and install. Are you using an ICOM diagnosis/programming. If not you will have to use standard tools because if you use ISTA I'm sure it's going to have you update other modules with a new install.