I have a 1998 NHW10. The inverter has recently started overheating, it appears because the Inverter Coolant Pump is behaving strangely. When I turn the ignition key ON, the inverter coolant pump runs normally but when I start the engine the inverter coolant pump stops running. This happens irrespective of engine/inverter/inverter coolant temperature. If I turn the engine OFF then turn the ignition back on without starting the engine, the inverter coolant pump runs normally again - until the engine is started, then it stops pumping again. I've heard that the GEN II inverter coolant pump has some mysterious electronics inside it but I didn't think it communicated with any of the ECU's & I don't know if GEN I I/C pump is in any way similar. Anyone know anything about this? Why would an apparently serviceable pump fail to pump only when its needed, then pump normally again when its not? Any knowledge/suggestions on this problem would be GREATLY appreciated! (btw: Brand new to the forum - Hi!)
Hi new, you should also mention this in the yahoo! group called Mk1_Prius. It is the largest group specialising in NHW10, and many Australian members.
Ideally you would obtain an NHW10 wiring diagram to shed light on your problem. However, since tech documentation for that model probably is only available in the Japanese language, maybe the NHW11 wiring diagram will be relevant. The NHW11 inverter coolant pump receives 12VDC via the IG2 relay. The IG2 relay coil is powered up when the ignition switch is in the IG-ON position. Power comes via the 15A AM2 fuse. If NHW10 is similar, you would need to check the IG2 relay to see if it remains energized when the car is READY. Is it possible that there is something wrong with your ignition switch, so that when you rotate clockwise from ACC-ON to IG-ON, the switch works properly. However, when you rotate further clockwise to START, then release the switch counterclockwise back to IG-ON, the switch no longer is providing 12V to the appropriate circuits? Good luck with your troubleshooting.
nhw10 pump is not turned on always like in nhw11. it's always off, and turns on by some temperature level.
