I recently got the Red Triangle of Death icon while driving home from the gym in my 2003 Gen I Prius (114K miles). Until recently I was getting 45mpg city/Hwy and the battery seemed to be operating normally, although discharging a little faster than usual. I’ve also noticed that the ICE motor has been working more recently while idling. I was stopped at a light then when I hit the gas there was a delay then the car lurched forward a bit, then the warning lights mentioned above came on. I took it to the Toyota Stealership and was quoted $3900 for battery replacement, and possibly another $1500-2000 for an ECU (they weren’t sure which one could be affected, or if just a battery replacement would fix the issue). Here are the codes that were found: P1636 HV ECU Malfunction P3002 HV serial communication P3006 Battery Levels unusually different Here is the text from the technician: Hybrid codes for HV battery levels are unusual. Graphed voltages and concluded that differences in voltages are our of spec. HV battery will need to be replaced to resolve this issue. Code P1636 HV ECU malfunction - Freeze frame data shows normal operation. Possible intermittent communication loss. Can be related to faulty battery. May need HV ECU. Will need battery replacement to continue testing. Does this sound like something common in a failing battery or more of a possible ECU failure/corrosion issue? Thank you for any help on this issue.
I don't know , but I'd look at the HV and 12v batteries for corrosion on the connectors before I did anything, clean and test with Dr Prius OBD2 APP
If you are able unplug the connectors on the HV battery (in the trunk left side) check for any corrosion, clean all four sides of each pin with a finger nail file if necessary, put dieletric grease on the plugs and plug them back in. It also sounds like your HV battery needs to have all the connector plates cleaned. Your cells have added resistance and wont charge.
@martinman151 It's pretty common for the Gen 1 HV batteries to develop corrosion where the HV battery sensor harness plugs into the HV battery ecu. The bad news is this sometimes leads to electrical arc damage/smoke and destroys the connector. Even serious corrosion will effectively destroy the ECU socket and/or the harness connector and minor corrosion can easily lead to signal problems. If you are able to do a bit of DIY, I would be happy to hook you up with an ECU and harness to install yourself. I have plenty of Gen 1 ecus and sensor harnesses that are in great shape. Think I probably even have one or two harnesses that have the nickel plated bus bars. As for the actual battery modules, keep in mind that if they're original, they're definitely getting to the point of needing some work. The great thing is that the car is low mileage and your modules may be great candidates for a prolong type refreshment instead of total replacement. That could be determined after examining the harness/ecu first and fixing that if needed.
