Gearhead Jim

I keep forgetting to cancel all my Onstar stuff and disconnect the antenna.

This week I received my September Diagnostics Report. The five different systems they normally report on each said "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."
They then tell me to unplug the device, press the blue OnStar button, then plug the device back in.

What I have plugged in is a Valentine "Savvy", which gets 12v power and reads the vehicle's speed from the OBD port. It does not send any info into the car, just reads the existing speed.

Do people with the Range AFM disabler get this same message if they leave the Range always in/on?

NSC5

The Range module does interfere with OnStar's ability to generate reports/run diagnostics. This is also true for devices like the Progressive "snapshot" device that plugs into the OBD-II port.

Rebel Yell

IDK brother, I had mine out last Saturday with the Range unit on and got the entire diagnostic report from OnStar. My unit is version 8.2, and that may make a difference from the older versions.

Zymurgy

I have a Window Valet plugged into mine and it does not interfere with the OnStar diagnostics.

tcinla

I've left my range plugged in an have received the onstar report so it does not interfere with OnStar.

rmorin1249

Same here. Mine stays plugged in all the time but turned off when I can remember to turn it off. Just received an OnStar report.

Steve Garrett

^^^^ +1

NSC5

I have an older version of Range so it sounds like they have updated it. I have been waiting for them to finalize one that doesn't cause a CEL but it sounds like it is time to update mine so that it no longer interferes with OnStar in the meantime.

Not everything plugged into the OBD-II port will interfere with OnStar but I recall last year one of the OnStar email blurbs specifically pointed out that at least some of the insurance plug-in devices were an issue; of course they also have a vested interest in getting you to use their reporting service to insurance companies rather than another device

Maxie2U

Yes, my Range Disabler interferes with OnStar if leftplugged in when they attempt to run a diagnostic report.

Avanti

Heck, I've even received a diagnostic report for a car I don't own! And, the wo I've received for my car have both had incorrect info... glad I'm NOT paying for this crappola.

Bvvet

How do you get your diagnostic report, I only received one, purchased car 7/15
Guess I have to call OnStar

LT1 Z51

I still don't get why people want to plug things into the OBD-II Port. If you want to add features, pay for a module that gets mounted somewhere (all you have to do is tap into the existing wiring). OBD-II ports are for test tools, and development work.

Moot point long term as the CAN Bus (other than Diagnostics) will be removed from the OBD-II port over the next 5 years from every car for security reasons.

GR Jay

You can the exact information from the OnStar app if you have it on your phone. It's really not all that exciting. Tells you how many miles are on the car, what the tire pressure is and what % oil life is left. I suppose if their was a system issue it might tell you that but I have never had one.

Gearhead Jim

Are you saying that adding another OBD connection somewhere else will solve the Onstar "problem"?

I don't really care that Onstar can't do their diagnostics right now, and I like the Valentine Savvy that powers the detector, then reads the car's speed and mutes radar warnings below whatever speed I set. I only plan to unplug/replug the unit if I take the car to a different dealer for work.

LT1 Z51

No, what I'm saying is you need to use a module that is designed to work on the system, or is designed to be a "sniffer" and not disturb traffic on the bus. A sniffer is undetectable, programs that we use at work to sniff a CAN bus (or as we call it data loggers) are CANalyzer, CAnoe, and to some degree CANape.

If a module isn't doing things right it can introduce NAKs (Not Acknowledged) onto the CAN bus eventually overloading it and causing "bus off" errors.

This isn't about OnStar working right, this is about potentially messing up other things in the car. OnStar not working right is a symptom that whatever you are plugging into the OBD port is behaving badly and causing issues. And while you may not notice them day to day, it doesn't mean they aren't bad.

The OBD port is not to be used for "adding" functionality. You are basically hacking your own car. If you want to add functionality, vendors which take the time to "piggyback" off of an existing connection with USCAR connectors and proper pins and thread gage are the way to go, they probably have more knowledge of the CAN bus and are less likely to cause issues.

At the end of the day, this is just my opinion as an automotive engineer, so I don't expect others to take it serious.

Gearhead Jim

I can take it seriously.

But I note that the devices insurance companies give people to track their driving habits, connect the same way and can cause the same "no Onstar diagnostics" situation.
Do those people unplug their unit occasionally? Once a year? Once a month? Once a day?

Or is there some easy way for me to make the connection with power and speed readout?