p261b and now check hybrid system

You need to purge all air from the system

 

what are you reading codes with?

 

P261B: engine coolant pump speed less than 900 RPM. Problem areas include the wiring to the pump, the pump, and the ECM (engine control module).

The pump wiring harness has five pins. Two of those pins should have 12V (when IG-ON) and one pin should be connected to body ground.

The engine coolant pump relay (ENG W/P relay in engine room relay box) condition should be checked.

If no other issues are found, the ECM might have a fault.

Obtain the factory repair manual info at techinfo.toyota.com which is a subscription website. That will show you the troubleshooting tree for P261B.

 

Don’t rule out a restricted coolant pump heat exchanger (radiator). I understand that you can see coolant flow in the tank but is it enough? If the impeller on the pump is struggling against a restricted flow, the pump motor will heat up, slow down and command a CEL .

 

Im having the same problem.

I recently bought a 2010 Prius used with 204k miles. Previous owner said he had replaced the waterpump himself and showed me receipt for the electric waterpump. I test drove it and it was fine. So i purchased the car drove it home about 1hr drive and it was fine. Next day i drove it to run errands for about 30miles, chk engine light comes on. then check hybrid system comes on. I chk it with Innova scanner and it said bad circuit 261b waterpump. So i tried clearing code and it didn't work. Read alot of forums and i learned that maybe i needed to purge air out of coolant system and it was good for 2 days. then same thing came back. Btw i ended up buying a better scanner autel mx808ts and it showed the water pump was not running. it would show the target speed around 2750rpm and the actual speed read 0rpm. I would clear the code and bang on the waterpump and it would work... then i would drive and it would randomly stop working sometime good for 1hr and sometimes it would stop after 2mins. and i would get stranded. Of course i had my scanner with me and a hammer to bang on the water pump to get it working again.

My question is Im not sure if its' the waterpump or a thermostat I need. because Im not sure if the thermostat has ever been replaced as I can no longer get a hold of the seller. and water pump does look brand new oem toyota. when the water pump is running, the water pump spins around 2700rpm-4700rpm when car is running. the temputure ranges from 141-190. I notice when the check engine light and check hybrid system pops on and makes me pull over temp is around 202. Also when waterpump does not work, the heater is cold. So do i need a new water pump or just the thermostat you think??? Please save me as this has been stressing me out and i cant find any info on this forums.

 

Replace the engine coolant pump, it is fairly obvious that is the problem since you have to hit it with a hammer to get it going. It would not hurt for you to replace the engine thermostat but that is not the root issue.

 

My experience with thermostats is no matter how old they are, there isn't any such thing as death of old age. They work by a pellet of wax expanding and pushing open a valve against a spring, and as long as the physics of expanding wax doesn't change, they go right on doing what they do.

One exception I have heard of, though, is if the engine severely overheats (maybe for some other reason originally). If the overheating is severe enough, the thermostat's wax might expand right out of the cylinder, and then it's a dead thermostat (not of old age but foul play). The engine may then continue overheating because the stat doesn't open, even with the original problem fixed.

 

Thanks guys... i also forgot to mention, when water pump is not running and car temp is in the 200's, the lower radiator hose from the thermostat is not hot. Meaning the thermostat is stuck closed? Could the waterpump not run because thermostat is not opening to let water into it?

 

Hello, I have a similar problem with my 2012 prius 3rd generation, 230k miles.. Please be patient when ready my questions as I am not that familiar with working on cars but smart enough to know where to go to get reliable answers and advice. My Prius stopped running while driving, pulled over, restarted and went about 2 mins before stopping again. This time it would not restart, yellow check engine light and skid control illuminiated with check hybrid system displayed. Took 12 volt in to get recharged since it was completely dead and then hooked up an OBD 11 scanner that came back with a P261B code (without turning engine on or driving it.) Confirmed the water pump is not running but leaves me with a couple questions.
1. Would a failed engine water pump be the cause for car not starting, the yellow check engine light and skid control to illuminate with check hybrid system displayed? Or is the pump just the part of an even bigger problem?
2. Is the engine water pump linked to the Power Inverter? I was hoping it would be since that is covered under the ZE3 extended warranty program.
3. Should I try to hit the water pump a few times to get it started so that I could have an All Diagnostics scanner ran on it?