2005 Prius Cooling Problems

P2601 refers to the CHRS pump, which will not affect engine cooling.

How is the car telling you it's overheating?

Have you been checking engine coolant level?

Which liquid are you looking at to see motion? About the only place to do that is in the inverter reservoir, which has nothing to do with the engine coolant or the code you're getting. The Prius has two separate coolant loops with separate pumps.

The hybrid battery cooling system has nothing to do with engine or inverter cooling, and does not have liquid coolant or a pump.

Do I understand that you recently changed the hybrid battery, and since then the battery fan has come on and never did before? Where did you get that battery and what kind of warranty do you have on it?

 

I think your pretty mixed up.

P2601 refers to the CHRS the "coolant hot water recovery system" which is under the front drivers side headlight. It has measured the pump and the pump is not turning. Really common issue.
It is an insulated thermos with a pump that stores hot engine coolant and then when your start the car it pumps that hot collant back inot the engine to meet emiisions quicker. A hot engine makes less emissions. BTW, in Europe cars they omitted that CHRS pump.

Your checking the Inverter Coolant pump reservoir which has nothing to do with the engine coolant. That pump cools the Inverter and the transmission.

And the battery fan has nothing to do with either pump really. 2 separate things...engine overheating and battery fan meaning the battery pack is overheating usually first sign of a failing battery pack. I suspect your not getting ALL the codes read properly. The OBD scanner must be Hybrid Capable P2601 is not a hybrid code .

If car is overheating its usually the mechanical water pump bolted to the front of the engine. Its probably bad and leaking coolant out of its weep hole. get a flashlight and with engine off look closely on the front of the engine the passengers side for bright flecks of green which is dried coolant which is coming from the water pump weep hole. Very very common. Then take the top black plastic cover off the top of the radiator so you can take the radiator cap off and check its level. I bet the radiator is bone dry.

You can only overheat that Little aluminum head motor once or twice before it will blow its head gasket $$$$ so get r done..

 

If your fan is turning on in the back when you have warning lights, you should have a hv battery issue. That's used to cool the battery that the ECU detects has a problem. Who sold you the battery?

The radiator dry is another thing all together

 

The fan is always on in the back But very low.
When it's on so loud you can hear it the hybrid battery is failing. Thats what one or more of the 11 codes it threw was trying to tell you. But for some reason you focused on p2601.

lately there has been literally hundreds of posts about failed hybrid battery's and all have the fan running loud in the back. Time for a new battery, do some research there's thousands of posts about it now.

And also like II said you have a leaking failing engine water pump. Standard water pump just like every car ever made has.
In addition to the bad hybrid battery and probably other issues. I would imagine it's mileage is over 200000 miles but who knows you never mentioned. The high dollar focus is the hybrid battery which is expensive.
So before bothering about the water pump focus on that as the car may be totaled if very high miles.

 

There's some confusion about the turbulence in the reservoir. The only place to see this is in the inverter reservoir, and this has no connection to the engine or P2601. And is that the reservoir that was dry?

Have you been checking the level in engine coolant reservoir, up front near the grille? There would be no turbulence in that, except in extreme overheat conditions and you wouldn't want to be near it then.

The Prius transmission is a CVT, and would never "slip." No gears actually "shift." Fault codes could deal with a failing motor-generator, for example, and you would not "feel" that until failure caused it to stop.

The only reason the battery fan would be on is one of the thermistors in the pack is sensing excessive heat. The new hybrid battery is overheating, so you apparently have a bad one. Or a problem in the transxle is drawing excessive current, but that's unlikely.

 

1. The Prius has two separate coolant loops: a) engine and b) inverter/transaxle
2. Therefore, there are two separate coolant reservoirs: the one next to the inverter is for the inverter/transaxle. The one behind the radiator is for the engine.
3. Which reservoir was empty? I am assuming it was the engine coolant reservoir behind the radiator.
4. If my assumption is correct, did you check the radiator fluid level in the radiator itself?
5. To access the radiator cap, you need to remove the large black plastic panel over the radiator. It is held on with six plastic fasteners. To remove a fastener, rotate the fastener with a Philips screwdriver while exerting upwards pressure on the panel.
6. Remove the radiator cap and fill the radiator to the top.
7. If you find that the engine coolant was depleted, the most likely reason is that the engine coolant pump is leaking fluid. Look at the pump pulley, if you see a pinkish or whitish powdery stain, that is dried coolant leaking out of the pump bearing. This can often be seen as a deposit on the air conditioner compressor housing below the coolant pump. In bad cases the spray will deposit on the sound insulation pad on the underside of the hood.
8. Where did you get the new traction battery from: a Toyota dealer, or some other source?

 

Did you check the fluid level in the RADIATOR?

 

Your primary concerns should be 1) where did the coolant go, and 2) why does the battery fan come on. The two tasks you're planning have little or nothing to do with these concerns.

The installer of the new hybrid battery should have cleaned the fan. There's no need to install a new one if the existing one is blowing. Check and see if it's dirty.

The CHRS pump has nothing to do with engine cooling or coolant loss, but it could have been damaged by low coolant. Fix the leak, then work on the pump.

Do you know that a full reservoir does not mean the radiator is full? The radiator will siphon coolant from the reservoir only after a heat/cool cycle, and if there's a large leak, the siphon may not work at all.

 

Did the dealership install that battery and botch it that badly? Is this a Toyota dealer? The cooling air ducts are extremely simple. I don't even remember connecting them when I've done battery work they're that mindless. I guess that explains the rattling sound you mentioned earlier, too.

Hopefully you got some work done at a deep discount after that error.

 

Errors happen. My wife still is angry at my dealer. He installed a rebuilt HV battery for me and it failed due to his not clicking home a connector when we were 900 miles from home. It cost us an overnight stay in a motel and $40 for the repair in Indiana (refunded by my dealer).

JeffD

 

It is most likely that some air is in the cooling loop for the engine that is causing the pump to lose its priming. See if there is turbulence in the coolant reservoir when your Prius is in "Ready".

JeffD

 

Check your thermostat for proper operation. If it is stuck closed, the engine will overheat.

JeffD