Did you also re-flash the BECM?
Sorry for the delay in response.Did you also re-flash the BECM?
^^^ The same happened to me. ^^^Just wanted to report I got it done over the weekend. I updated the Battery Energy Control Module as reported by OP and the latched DTCs didn't come back. Guess an updated Hybrid Powertrain Control Module 2 (HPCM2) without updating the BECM results in a conflict issuing the latched Service High Voltage Charging System DTCs.
If I understand this correctly, you are stating that the circuit for the coolant level or WOT sensor plug does not require resistance in order to send the proper signal to the hpcm2 and desires instead to see ideally, a dead short on that circuit throughout, correct? If that is the case, then the WOT defeat plug, or sensor rather, is really just a jumper plug that you could otherwise wire the leads together to short only without the $30-$40 price tag. I assumed that the WOT defeat plug was either a short jumper or at least included a resistor wired in series that the hpcm2 is/was expecting to see. I've defeated a few airbag codes by using resistors instead of deal with the expense of replacing the airbags on a wrecked Volt that I repaired a couple years ago.. Let me know if we are on the same page, much appreciated.I have seen this on a few cars, comes in for the message and the sensor showed a failure as history only. Replace the sensor and program the modules just to have the car come back with the same issue within 6 months. Called GM tech assit and they have no new ideas other then to replace the sensor and the connector for that sensor. Did the repair and a month later, same issue. This time I rewired the complete circuit from the Hybrid Powertrain Control Module 2 (hpcm2) to the sensor. New terminals in the hpcm2 connector, new wires from the hpcm2 to the new connector and sensor. All terminals were soldiered to the wires for the best connection possible. This bypassed one connector located under the hood so the new circuit is much better. After this
repair, I have not seen the car back for this issue, repaired over a year ago (knock on wood). The problem with this circuit is that its a very low amp circuit and its looking for a small voltage drop to set the code. So if there is just a small amount of resistance in the circuit, it can cause this issue. I have done this repair on 3 cars now, not one has come back, now any car with this issue that I get has this repair done.
I had the Service Theft Deterrent System alert and it was caused by a weak ground connection. You can find details here to compare to your symptoms:One thing I noticed however, was that when I was done the reprograms, the main dash said 'service theft deterrent system' before I took the car out of service mode. Once out of service mode, the main dash did not show any messages. I saw the 'service theft deterrent system' message after each re-programming, because I took it out of service mode and powered up normally in between them.
Has anyone seen this message before? Some quick searches have shown that a degrading 12V battery could cause this, so I'm thinking about replacing that out of caution. I bought the car used and have had it for two years, so it wouldn't surprise me if it's starting to degrade.
kwantorbit. Did you find these pins on HPCM2?I'm checkin the Service Manual for 2012 Volt, HPCM X1 connector, PIN 32 is labeled AC Refrigerant High Temperature Sensor Signal, circuit 732, Color: WH/L-BU and PIN 33 is labeled Low Reference, circuit 452, Color: BK/VT. According to diagram you shared, PIN 32 is circuit 68, Color: L-BU/YE and PIN 33 is circuit 476, Color: BK/L-GN. It might be possible it corresponds to a different year model or Ampera has a different schematics. Nevertheless, I'll try to verify correct PINs during the weekend.
Again thanks for your help.
This thread originally began with the OP wondering about failures where SHVCS was triggered even with WoT's plug. Well, that just happened to me. I had the SHVCS four times before moving to WoT's plug. It's been solid for some time, but SHVCS triggered today. BUT, what makes this curious....is that when I checked under the hood....my batter coolant bottle was TOTALLY empty! Well, that's not good. And is very interesting. Now, everyone will be saying that Wot's plug is fine and SHVCS triggered because other sensors detected the low coolant. But, no. Long time veterans on this topic will know that WoT in multiple posts was absolutely clear that the ONLY way to trigger SHVCS was THIS sensor. But, this sensor on my Volt is currently just WoT's plug. So....WoT's plug has unfortunately failed for me and it's coincidence the fluid actually IS empty. Who knows how long it's been like that. As WoT stated, and actually tested himself, Volts can operated with an empty battery collant bottle.My early 2012 developed the Service High Voltage Charging System error message months after having installed the WOT sensor replacement.
did you solve your problem, I have the same problem right nowAnd write us what DCT you have revealed? WOT wrote about the fact that there can be many other errors. It is true that he also wrote that SHVCS is revealed only as a result of low level or problem with the installation. So the question is what is the module saying now? I have two errors P1FFF and P1E00 with a 2.47km resistor connected. That is, I removed a magnetic contact from the sensor that contained a value of 17.4 to zero. And the error occurred again. The fact that after 7 days but occurred. I was surprised by the frozen frame that showed the 0.00kochm insulation test. This is a short circuit. After connecting GDS2 and doing the test I have the result = 650kochm, so the question is where is hypocrisy ?. Someone describe how to check the insulation with a meter. Maybe it is a problem with some 380V device. The only question is why the errors concern the sensor and there are no others?