Prius overheating after water pump replacement

To be a little more specific, the one line (WPO), with the red pointer aimed toward the water pump, uses pulse-width modulation to control the pump's speed. It switches repeatedly between near 0 volts and near 12 volts, and the higher the "duty cycle" (meaning the wider the high pulses, or the more of the time it is near 12 volts), the faster the pump goes. When the low and high times are equal (it looks like a square wave on a 'scope), that's a duty cycle of 50%, and the pump goes about half speed.

It is most easily seen on an oscilloscope, but you might also just have a multimeter with a duty-cycle button that will show you the % duty cycle directly. Failing that, if you have a slowish average-reading DC multimeter, you can get a decent idea what's going on: if the average looks around 6 volts, it's around 50% duty. You might be able to do the same with a "true RMS" AC voltmeter, and a little bit fancier math.

Notice the averaging meter won't show you the difference between, say, a properly-functioning call for 50%, and some kind of wiring problem where the duty cycle is 100% but the pulse only gets up to 6 volts. A 'scope would show that difference clearly. You could check for that with a simple meter by also switching it to peak-reading and making sure the peaks are still 12 volts.

The other line, WPI, with the red pointer aimed back toward the ECU, is the pump's tachometer signal, just so the ECU knows how fast the pump is really going. It does not use pulse-width modulation; it just outputs a simple square wave, two cycles for every revolution of the pump. So if you use a 'scope, or a multimeter with a frequency-counter button, and read off the square wave's frequency in cycles per second, just multiply by 30 and that's the pump RPM (and should be close to what you see on any OBD scan tool watching the Elec Water Pump Spd from the ECU). That's all there is to that.

 

Dealer

 

Where did you get the pump before? I am having the same issues but I ordered my pump from a Toyota dealer. Wondering if I should go to a Toyota dealer and ask them why the water pump doesn’t work.

 

From intital post:

Did anything in particular prompt you do this change? Was it already overheating?

Ever cleaned the EGR circuit?

Have you had the car since new? If not, when you changed the coolant, was there any goopy stuff, evidence of stop-leak product?

 

I have similar issues with my Prius. I have a 2011. Changed out engine, water pump, sensor and thermostat. I have issue when I drive high speeds 70-80 mph up hill. Reservoir very hot almost to boiling temperature. Temp red light would turn on or flash and then when I slow down it will eventually turn off. My mechanic replaced literally everything minus the radiator and the inverter coolant pump. Can anyone please help????

No codes or no check engine lights just the red light engine temperature turns on when driving high speeds up hill for long periods of time.

Is the issue temp sensor on EGR pipes?

My mechanic has replaced with all OEM parts. Any advice?

Toyota service rep says might be inverter water pump, radiator clogged up, or water pump.
Just had Toyota dealership diagnosed and they check for any leaks so it’s not the engine. They said water pump and thermostat. My mechanic replaced those 2 parts. I thought I was in the clear but I wasn’t. The car still overheats when driving high speeds 75-80 mph for long periods of time and red temperature light turns on again uphill at high speeds. Anyone please help and TIA

 

Again counterfeit parts

 

"Minh: ...My mechanic has replaced with all OEM parts....

 

@Minh , this doesn't make it easier:

 

like its been said bad.. counterfeit parts.. this was my solution to what you are facing with your Toyota Prius water pump

 

Correction-

Car Scanner app does not currently show "Elec Water Pump Target Spd" or "Elec Water Pump Spd". It has a “Water Pump Duty Cycle” but it is in fact the Inverter pump. It does have Inverter Water Pump rpm.