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I just got my monthly email from OnStar and I was surprised to see that all the systems displayed this error message:

"We were unable to successfully complete a diagnostic test. This issue may be caused by an aftermarket device plugged into your vehicle's diagnostic port."

Well, at least their error message is descriptive. I'd have been mystified as to why it all failed without that tidbit of info.
 

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"We were unable to successfully complete a diagnostic test. This issue may be caused by an aftermarket device plugged into your vehicle's diagnostic port."
Well Hmmm.... Do you leave your DD turned on all the time? I've not gotten this error report, but my DD is always turned off while I'm charging, and my off-timer is usually on the order of 10 or 20 minutes anyway. It also has a tendency to be sitting on my desk late at night as I reprogram skins (so that last case certainly wouldn't affect anything).

I can't imagine the DD affecting On*'s ability to run diags on the car if it's turned off. I'm really rather surprised it can affect their ability if it's turned on, since all it does is query status. Then again the phone module must be recovering status as well, so maybe it hangs out on the OBD bus too, and gets confused if it sees query/responses it didn't originate?

I know you were doing some charge time OBD analysis. Perhaps that interfered?

And if the modem's doing a bunch of query polls while the car is otherwise off, that might be something *very* interesting to the OBD snooper contingent (Volt and possibly Leaf both - since CarWings may do something similar).
 

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And if the modem's doing a bunch of query polls while the car is otherwise off, that might be something *very* interesting to the OBD snooper contingent (Volt and possibly Leaf both - since CarWings may do something similar).
I did try looking at the OBD data while I was talking to OnStar, but didn't find anything that looked like it was related to OnStar. I do want to check when myvolt.com connects, but I'm not expecting to get anything from that. Given that there are several buses, only one of which I can access, it's possible that there is OnStar data going on the other. My hunch, though, is that the data they get is accessible via OBD (if you know how).

It is interesting that OnStar "knows" that there is a device there. Perhaps OnStar makes OBD queries to get the data it supplies, and the DD was using up too much bandwidth with its requests.
 

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Have you checked your DTCs? I did a diagnostics scan and one DTC showed up:

U183E: Lost communication with OnStar Module on bus F (history)

I have no idea what that means, other than it looks like DD and On* may not always play well together.
 
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