Landcrabmech Posted February 5 Share Posted February 5 Hi Everyone, Could someone please help me? I have replaced the 12V battery on my 2008 RX400H and now the dealer says I fried the HV control ECU. How would this happen? I have been a certified HD Mechanic for 28 years and have never seen this before. Now I am stumped. Can I replace the HV control ECU with a used one or does it have to be a virgin one from lexus? Issues are the HV battery does not charge when the engine runs, many codes came up when I replaced the battery, I cleared the codes with Techstream and still does not work. The engine will start up but when I try to drive the check hybrid light comes on, the check vsc comes on. I cleared these and still will not drive and charge HV battery. I had a company send me an ecu that the programmed with the info from my original ecu but still not functioning properly. What is the chance the hybrid driver clutch has failed inside the transmsission? How would I check it? I cannot find out much information from the dealer or online about this car. All the dealer told me was they followed the troubleshooting tree and it says " replace HV control ECU". Please help, My car has been down for 8 weeks now Scott Quote Link to comment Share on other sites More sharing options...
HaloRomeo27 Posted February 25 Share Posted February 25 On 2/4/2024 at 9:52 PM, Landcrabmech said: Hi Everyone, Could someone please help me? I have replaced the 12V battery on my 2008 RX400H and now the dealer says I fried the HV control ECU. How would this happen? I have been a certified HD Mechanic for 28 years and have never seen this before. Now I am stumped. Can I replace the HV control ECU with a used one or does it have to be a virgin one from lexus? Issues are the HV battery does not charge when the engine runs, many codes came up when I replaced the battery, I cleared the codes with Techstream and still does not work. The engine will start up but when I try to drive the check hybrid light comes on, the check vsc comes on. I cleared these and still will not drive and charge HV battery. I had a company send me an ecu that the programmed with the info from my original ecu but still not functioning properly. What is the chance the hybrid driver clutch has failed inside the transmsission? How would I check it? I cannot find out much information from the dealer or online about this car. All the dealer told me was they followed the troubleshooting tree and it says " replace HV control ECU". Please help, My car has been down for 8 weeks now Scott That does not sound like an ECU problem that reminds of the battery relay switch and if i was going to guess at it i am going to say it is full or water and corroded they sell a brand new one for about 380 dollars but you need to fix the water issue first Quote Link to comment Share on other sites More sharing options...
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