p261b and now check hybrid system

Discussion in 'Gen 3 Prius Main Forum' started by Azlandshaper, Nov 17, 2019.

Tags:
  1. Azlandshaper

    Azlandshaper Junior Member

    Joined:
    Mar 5, 2018
    16
    11
    0
    Location:
    Old Pueblo
    Vehicle:
    2010 Prius
    Model:
    Four
    My prius has 227k. Its a 2010. Has been acting up as of late. I did a recent EGR cleaning and after reassemble it the car proceeded to over heat (temp light came on). I heard a bad noise coming from the water pump so I replaced it w an Aisin (sp?). The old pump was locked up upon inspection. Still after replacement we are getting a temp light. I changed the therm as well after realizing the hose from the pump to the rad wasnt heating up after a decent drive. Well the next morning I have a check hybrid system light, car drives for 3 miles and then quits. I pulled the bat cables to reset things and tried to continue on my way only to get 5 miles and have the CHS light again and the gas engine quit out on me. Now the CHS light illuminates almost like clock work after a short drive. CEL codes are low power and p261b (current in the water ??).
    Traction battery is now down to two bars and the car is dead in the drive. Any thoughts? I checked a few fuses and found nothing wrong. Dont know what relays to look at or if thats even pertinent.

    Appreciate the help.
     
  2. Pluggo

    Pluggo Active Member

    Joined:
    May 23, 2016
    463
    410
    0
    Location:
    Folsom, Pennsylvania
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Advanced
    You need to purge all air from the system
     
  3. Azlandshaper

    Azlandshaper Junior Member

    Joined:
    Mar 5, 2018
    16
    11
    0
    Location:
    Old Pueblo
    Vehicle:
    2010 Prius
    Model:
    Four
    Done and no change. Reset the codes and didnt make it 5 miles before the CHS indicator popped up and the gas motor shut down. There is deff now coolant flowing through the coolant pressure tank. Air was successfully purged and I now have heat as well.
     
  4. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    83,689
    36,605
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    what are you reading codes with?
     
  5. Azlandshaper

    Azlandshaper Junior Member

    Joined:
    Mar 5, 2018
    16
    11
    0
    Location:
    Old Pueblo
    Vehicle:
    2010 Prius
    Model:
    Four
    Been getting them read at autozone. I know its not ideal but I would be paying an arm and a leg at the dealer and my tech-stream is en route as I type this. Not a lot of options atm.
     
  6. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    18,046
    6,016
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    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.
     
    SFO likes this.
  7. BZzap!

    BZzap! Senior Member

    Joined:
    Jun 13, 2012
    1,446
    733
    0
    Vehicle:
    2012 Prius
    Model:
    Two
    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 .
     
  8. Sneakyx16

    Sneakyx16 New Member

    Joined:
    Nov 18, 2019
    4
    0
    0
    Location:
    Castle Rock, Co
    Vehicle:
    2010 Prius
    Model:
    ----USA----
    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.
     
  9. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    18,046
    6,016
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    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.
     
  10. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    7,790
    5,436
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    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.
     
  11. Sneakyx16

    Sneakyx16 New Member

    Joined:
    Nov 18, 2019
    4
    0
    0
    Location:
    Castle Rock, Co
    Vehicle:
    2010 Prius
    Model:
    ----USA----
    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?
     
  12. Azlandshaper

    Azlandshaper Junior Member

    Joined:
    Mar 5, 2018
    16
    11
    0
    Location:
    Old Pueblo
    Vehicle:
    2010 Prius
    Model:
    Four
    Lower Rad hose is not hot because the pump is not moving hot water through the system. The lower hose is the last spot to heat up as water exists the radiator and then passes through the pump.
    Do you ave coolant moving through the pressure/ refil tank?
    This is one way to know the coolant pump is active. You will see coolant flowing from the top hose attached to the pressure/ refill tank.

    Either way your due for a pump. Might as well do the therm while there since its a $35 part and is attached tot the pump and both will require draining coolant and refilling and bleeding air.
     
    Sneakyx16 likes this.
Loading...