my gen I Prius started having issues. Every time I drive about 30 miles the triangle and check engine light come on with a ding and also my dash lights immediately dim. I just replaced the 12 v battery. Still no fix. I also switched the fuel pump relay with the horn relay which seemed to help the dash light dimming problem (oddly enough) So I'm not sure what it could be. Also I live in Utah and it's getting into the high 90s and I only started to notice this problem as it started getting hot outside. Coolant inverter problem? I've ordered a replacement so hopefully that will fix it. Any other ideas? Thanks
It does sound like the inverter coolant pump has failed. Make the Prius READY, open the hood, and look at the inverter coolant reservoir. You should see a "step" in the fluid level and turbulence in the fluid which shows the pump is running. If the pump is not running then it needs to be replaced. Note that it is not easy to get air out of the Classic Prius inverter coolant loop and that must be done before the car is returned to normal use. Use a multimeter to measure voltage across the 12V battery when the car is cold, and also when the dimming dash light issue occurs, which is evidence that the voltage has declined.
