How can we troubleshoot isolation issues with the 500e?

[Scotty]

My cousin has been dealing with some issues with his 500e, which has under 25,000 miles but definitely needs some TLC. After getting it, he replaced the 12V battery and manually charged the high-voltage battery, and thankfully, all the cells are healthy. However, when he ran an isolation test, it showed good battery isolation but reported the vehicle isolation as either 0.00 MOhms or 0.06 MOhms, which raised some concerns. Interestingly, the Power Inverter Module and Onboard Charging Module didn’t report any faults, still the Electric Vehicle Control Module flagged a couple of faults that seem more like effects than actual causes.

We are wondering if anyone else has encountered a similar vehicle isolation fault, so any insights would be really helpful.

 

[LucyM]

My cousin has been dealing with some issues with his 500e, which has under 25,000 miles but definitely needs some TLC. After getting it, he replaced the 12V battery and manually charged the high-voltage battery, and thankfully, all the cells are healthy. However, when he ran an isolation test, it showed good battery isolation but reported the vehicle isolation as either 0.00 MOhms or 0.06 MOhms, which raised some concerns. Interestingly, the Power Inverter Module and Onboard Charging Module didn’t report any faults, still the Electric Vehicle Control Module flagged a couple of faults that seem more like effects than actual causes.

We are wondering if anyone else has encountered a similar vehicle isolation fault, so any insights would be really helpful.

It sounds similar to what I’ve experienced. An isolation meter might test at a higher voltage than a multimeter, so maybe that’s why the isolation fault is showing up, and also, when the cables are disconnected, the BPCM can’t perform an isolation test, so it makes sense that it would show zero or maybe a small reading like 0.06 MOhms, just like your cousin saw. If there’s an open circuit in the HV Interlock Loop, it would deactivate the contactors, which could explain the faults your cousin’s Electric Vehicle Control Module is flagging. Has anyone else dealt with this?

 

[NovaNomad_]

I had to make sure all the little clips on the cables were locked in place to fix the HVIL error.

 

[Scotty]

It sounds similar to what I’ve experienced. An isolation meter might test at a higher voltage than a multimeter, so maybe that’s why the isolation fault is showing up, and also, when the cables are disconnected, the BPCM can’t perform an isolation test, so it makes sense that it would show zero or maybe a small reading like 0.06 MOhms, just like your cousin saw. If there’s an open circuit in the HV Interlock Loop, it would deactivate the contactors, which could explain the faults your cousin’s Electric Vehicle Control Module is flagging. Has anyone else dealt with this?

Thanks for sharing your experience...That explanation makes sense, especially about the BPCM and HV Interlock Loop. I’ll have my cousin double-check the wiring and connections to be sure.

 

[Scotty]

I had to make sure all the little clips on the cables were locked in place to fix the HVIL error.

I’ll pass this along too