Name that tune...

You’re getting out of the car, walking ‘round the front? It’s running or off?

 

I have read about the "3 way" coolant control valve going bad and causing that kind of noise. The valve has a motor and a position sensor. The sensor gets worn and causes position signal to be erratic- so the ECM commands the motor back and forth as it tries to "hunt" for the correct position.

The valve is located between the inverter and the radiator support to the driver's side. The ECM runs the pump & valve for the Coolant Heat Storage tank after you turn the car off. The valve controls engine (ICE) coolant in/out of the tank & to the heater.

The ECM pumps hot coolant into a thermos tank. That's used to help the engine warm up quicker after you start the car the next day (or even 2-3 days later). So you might hear also the pump and valve after you go to "ready" but before the ICE starts.

Usually this type of fault triggers a P1121 code in the ECM, but not always.

Posted via the PriusChat mobile app.

 

Here's one of the threads where we've discussed that noise before:

3 way coolant valve noise. | PriusChat

For more details on what's really going on, there's this one:

P1121 and inside the coolant valve | PriusChat

The valve and the pump that mr_guy_mann mentioned are separate parts, and do different things at slightly different times.

The pump just runs after engine shutdown, and before startup, to store hot coolant away in the thermos or to preheat the engine with it.

The valve shifts between different positions for pumping into the thermos, out of the thermos, or normal engine operation where coolant just circulates through the engine and heater. The valve has a position sensor that reports back what position it's in. Any time (any time, pre-start, post-shutdown, or while the engine runs), if the valve doesn't report being in the right position, the ECM will try to send it there.

If the valve position sensor is flaky, and never looks like it's in the right position, the ECM will be stuck sending the valve back and forth to try to find the right position. That's the washing-machine noise.

 

I had that sound for months on my car until the valve finally triggered that code. Replaced the valve and no more sound!

 

Wig-wag? lol... What in the world does a wig-wag sound like?

 

Click-schlunk.

Wig-wag was the actual name of a part in most washing machines of a certain vintage. Those machines used a single electric motor to drive a gearbox that could either move the agitator back and forth, or spin the tub around, or be in neutral while the drain pump ran.

Shifting that transmission was done indirectly by solenoids, but those weren't powerful enough to directly shift the linkage. Instead, there was the wig-wag, a little appendage that the transmission always drove back and forth, and when one of the solenoids clicked in, it would lock one of the shift linkage pieces down to the wig-wag, and the motion of the wig-wag would push it to complete the shift.

Which is why every time one of those washing machines shifted from one part of the cycle to the next, the sound was click-schlunk.

 

Interesting how the generation you grew up in defines how you describe sounds... For me the best description of failed 3-way coolant valve sensor is "sounds like an old computer disc drive."

 

The second link I gave in post #4 is to a thread with pictures of the valve disassembled. There's an ordinary potentiometer in there, if you feel up to changing one of those. Many people will just replace the valve.

 

If someone readings this ends up repairing rather than replacing a three way coolant valve please post pics and other details so we can learn how to do it too.