I've been having this issue with my 2010 Nissan Altima Hybrid where it completely loses electrical power upon shut of. This happened initially a few weeks ago and has happened 4 times since. The first time it happened, I parked and pressed the push button start/stop to turn the vehicle off and the entire vehicle lost electrical power. It remained in this state for a few minutes until suddenly everything started coming back on. After things came back on I left the vehicle parked while I ran errands and when I returned and started the car everything appeared normal except my check engine light was on. I drove home planning to scan for codes but unfortunately turned off the vehicle again out of habit and the same complete loss of electricity occurred but this time without returning. The next few days, I started investigating by checking the 12V battery (which had been replaced in April) and all fuses/relays. The only discovery was that the terminal next to the positive terminal (used for jumpstart under the hood) in the high voltage fuse box was at ~2V when it should be the battery voltage (~12.8V). I also noticed that whenever I disconnected the battery, reconnected it, and opened the driver side door, I hear some relays clicking and then the car makes a high pitched beep sound for 3 seconds. After some more investigating, I was calling it a day and opened the driver door to manually lock up but I noticed the push button was illuminated. I turned on the car and everything was operating normally again. I remeasured the area with low voltage and it was now the same as the other terminal. The car ran and drove perfectly. At this point I decided to take it to a hybrid vehicle mechanic to get things checked out but half way there the engine began to shudder, turned off, and all kinds of dash lights came on. I drove on the Hybrid battery for a minute or so but that quickly drained and I pulled over. The car still had electrical power when I turned it off. I got it towed to the mechanic and after a few days they discovered one of the ignition coils had shorted pretty badly but they didn't experience the complete loss of electricity. I replaced the ignition coil and the car was running and driving perfectly again. I test drove it 3 or so times and no issues came up. Just as I was beginning to regain confidence in the car, I decided to drive it to a nearby grocery store and upon turning it off the complete loss of electricity returned. Again I began investigating and it was in the same state as before with low voltage in areas that should be battery voltage. I had to get it towed home and have continued investigating and reading through the service manual routing circuits to determine the source of the low voltage. I have found that terminals into fusible link G have the battery voltage on one side and low voltage (varies 0V to 2V) on the other. It seems that any area connected to the "Hybrid Vehicle Control System" is at this low voltage. Another interesting thing I've observed is that voltage on pin 3 of where the IGCT Relay connects is the battery voltage when fusible link G is inserted but drops to the low voltage when G is removed. Fuses 60-64 are all at battery voltage. Sorry for the length of the post, just want to provide as much information as possible.
Any help is greatly appreciated.
Last edited by mikemikey96; 08-09-2023 at 11:37 AM.
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08-09-2023, 11:23 AM
Complete Loss of Electrical Power
