ScanGauge almost killed my traction battery

OK, might have been *partly* my fault, you decide. Please excuse the lengthy details. Timeline:

Wednesday kids said the check engine light on in Sienna. I take the SGII out of the Prius and use in Sienna to get the code, looked like loose or faulty gas cap. I tell the kids, they say they found a bunch of parts in the filler hole and thought they came out of the gas pump. I put the parts back in the gas cap (at least they were smart enough to keep the parts) and tell them to let me know if the light is still on after driving it a while, put SGII back in Prius.

Thursday kids say check engine light still on in Sienna, move the SGII again and reset the warning light and put the SGII back in the Prius. No further Sienna problems.

Friday I start the Prius and the red triangle comes on, I figure from the SG remembering something from the Sienna. I reset the codes and had no trouble with commute.

Sunday I drive the Prius the first time since, fuel is full, Red Triangle comes up and I figure SGII is still remembering fuel system errors from Sienna and I reset codes again and start driving. I go around a mile and see that SOC is down to 42% and think it should be higher, and notice ICE is not coming on. A few seconds later I look again and it's down to 32%, I pull over and shut down the car. I restart and the ICE still will not run. I shut down, pull out the SGII plug, start again, and ICE fires up and starts charging the battery, I plug in the SGII again, and I start driving when its back up to 40% SOC and car runs normally.

I'm not sure what happened here but I'm certain it involved the SGII. I also could have a few details not right in the description of events above. I assume my main mistake was plugging in the SGII with the Prius not running. I think maybe when the Prius booted up it got some garbage Sienna info from the SGII and it blew its mind. I doubt if the traction battery was damaged from going down to 32% once, but it could have quickly turned into a disaster.

Lesson learned: Be wary of swapping ScanGauge between vehicles!

 

I think before this the only red triangle my Prius had thrown was door ajar, I don't think it could be coincidence that when the ScanGauge was moved back to the Prius, it threw 2 check engines, each after it had been plugged into the Sienna. I had not pushed any buttons on the SG except to reset the check engine light, and I didn't push them very fast. I didn't read any codes on the Prius, and I didn't check any setup parameters on the SG. It seemed to remember it's display on the Sienna and the Prius, I think the Sienna had a SOC of zero if I remember correctly. Since I got the SG last January, after I had programmed what it displays I haven't touched the settings since. I had to look at the book to see how to reset the Sienna's check engine light. I recommend everyone be cautious when moving the SG from Prius to another Toyota with a problem and then back to the Prius. You could have a disaster in short order.

 

I agree, sounds exactly like what happened. I don't remember starting the car before plugging in the Scangauge first time when I installed it, maybe I just got lucky or maybe it makes less of a difference when it's never synced up with a car before. In the future I'll definitely start the car before plugging it in!! It could have been a $3000 mistake.