Hello, I recently had an issue where where the P2601 error code was displaying on my prius, I ended up clearing it a few times this week and ordered a replacement auxiliary pump. Following some instructions I removed the tire, replaced the inactive heat sink pump and reconnected the wiring. After attempting to refill the overflow, and doing the bleeding, the fluid is circulating but does not appear to be filling up the gallon of fluid that was drained. I checked the voltages on the pins going into the small auxiliary motor and it did not have any voltage. I was reading up that there was a relay that may be the source of the issue, is there an easy way to test the relay and force the pump to run?
The coolant heat recovery system pump receives voltage only a few seconds at a time upon startup and shutdown, so you have to force the pump to manually run. You can use Toyota Techstream to do that, or you can do this manually by shorting the correct terminals of the CHRS relay socket. Do not run the pump more than 30 seconds at a time, to avoid overheating it. Even after you think you are done, it is not easy to get all of the air out of the engine coolant loop, so keep checking the radiator fluid level at the radiator itself (not just the overflow reservoir) on a daily basis when the engine is cold, and fill as needed. See my post #22 here: Changing engine coolant | Page 2 | PriusChat
