Bad Water Pump or Spark Plugs?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by ShenmueTacos, Aug 31, 2019.

  1. ShenmueTacos

    ShenmueTacos Junior Member

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    On my way to work today the check engine light, red triangle, VSC, and tire pressure light came on. I pulled over briefly and turned the car off and back on. During this time I checked the 12V battery through the maintenance mode and the battery had 12.4 while off and 14.0 while on. I checked the oil level as well and there was plenty of oil with no signs of burning. I turned the car back on only the red triangle and check engine light was on. I drove on to work as I was closer to there instead of home and the car seemed to act normal while driving but seemed a little rough on idle at a red light before the engine shut off. It started back up fine once the light turned green. The traction battery appears to be fine as well. State of charge doesn't fluctuate like crazy and doesn't really act much differently than my 2015 Prius' battery. The battery bars made it up to green at one point and stayed there for a long time before going back to blue.

    I purchased the car with 108K on it and it now has 110K. I have looked up service records on the Toyota Owners website. The car had the water pump, engine coolant, and 12V battery replaced around 80K in late 2015 by the previous owner. However, I don't see any indication of the spark plugs ever being changed. I also wondered if the pump has malfunctioned, even though it isn't that old. The car is due for an oil change in about 100 miles and I was originally going to have the the spark plugs changed then anyway.

    As of right now, I don't have an OBI-II code reader yet but plan on ordering one today but was wondering if anyone could tell what the problem may be simply from my description.
     
  2. sam spade 2

    sam spade 2 Senior Member

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    Your 12 V battery is old enough that it is suspect.
    The 12.4 reading is another possible indicator that it is going bad.
     
  3. jerrymildred

    jerrymildred Senior Member

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    Nope! Need the codes. Everything else is total speculation. Let us know when you get the code reader. Hopefully, you made sure to order one that reads the Prius proprietary codes. Most code readers do not. The best option (and cheapest if you have an old Windows XP or Win7 32-bit laptop) is one of the Techstream and dongle kits available through Amazon or Ebay.
     
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  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Start by checking tire air pressure.
     
  5. edthefox5

    edthefox5 Senior Member

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    See if the Inverter cooling pump is bad.

    Check Inverter coolant pump:
    Make the car ready and then open the hood and take the cap off the inverter coolant reservoir and with a flashlight look inside at the fluid it should look like its boiling which means the pump is working. If the red fluid is not moving at all the pump is bad.

    Check the engine coolant:
    That must be done by removing the radiator cap. Disregard the plastic overflow tank coolant level. The level in that tank is pretty meaningless. You must look inside the radiator itself for correct level check.

    Take the black plastic cover off the top of the radiator. It has 5 screws easy way to remove screws is to snake your hand behind the screw and give the screw a little push as you unscrew it with a screwdriver. With cover off you can access the rad cap its on the left. With car off and engine cool open the cap the fluid should be at the top. If low or very low you have a bad ice water pump. The fluid level in mine has not lost a drop in 12 years.

    You do not have to put the screw's back in that cover. The cover fits snugly and the hood traps it in when closed. My cover has been missing screws for about 10 years. I like to check all the fluids every Saturday and the loose cover makes it fast and easy to check rad level. Low coolant is the only hint you get that the ice water pump is leaking. They start weeping when going bad. if not addressed the engine will overheat and destroy the cyl head. You will never know till the check engine light comes on by then its too late. Many an overheated engine replaced on this forum. No temp gauge is ridiculous.

    You have no engine temp gauge so it behooves you to be vigilant. Your wallet will thank you.
     
    #5 edthefox5, Aug 31, 2019
    Last edited: Aug 31, 2019
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  6. ShenmueTacos

    ShenmueTacos Junior Member

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    Updating my thread because it turned out that the issue from before was the spark plugs misfiring. I did buy a Carista OBDII adapter and downloaded both the Carista App and the Torque Lite app. Both were showing the same codes for the plugs. I got those replaced, an oil change, and went ahead and had the coolant replaced a day or two after I posted on here. The car ran great until yesterday...

    On my way to work yesterday all the same dash lights came on and I pulled over. Like before, everything seemed fine when it came to the oil levels, 12v voltage was the same as before, traction battery SOC was good, there is turbulence for the inverter coolant and the inverter didn't appear hot. However, I am now getting the P0A94 code. Looks like the apps I have don't show any sub codes, just the "DC/DC Converter Performance." The car drives fine after throwing the code and the SOC of the traction battery goes up and down normally still. If it wasn't for the red triangle staying up you wouldn't know of a the issue. I did clear the code yesterday to see if it would come back up. I drove all the way home (40 miles) and it never came back up, but the code came back this morning as soon as the car was started. Drove the car around and it drives perfectly fine. Again, if it wasn't for the triangle then you wouldn't know of the problem. I did open the hood to double check the coolant and there was still turbulance and the inverter was not hot. If the inverter completely failed, I wouldn't be able to drive the car at all, correct? I also know that my 12v is going on 5 years old. Would a 12v that's going bad throw this code or would that be a different one?
     
  7. sam spade 2

    sam spade 2 Senior Member

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    Possibly.
    A weak 12 V battery can cause all kinds of erroneous codes to pop up....but there often is more than one and sometimes they come and go and change.

    You should definitely check the voltage on the battery itself after sitting overnight and BEFORE starting the car.
    Then again after READY.
    Should be around 12.5 when "cold" and a bit over 14 when running.
     
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  8. ShenmueTacos

    ShenmueTacos Junior Member

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    Okay, I'll have to double check it tomorrow morning. If I remember correctly, I believe the voltage was 12.4 yesterday and today before startup according to the MFD.
     
  9. sam spade 2

    sam spade 2 Senior Member

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    You should NOT use the MFD for this reading......because some things must be "started" for it to work.
     
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  10. ShenmueTacos

    ShenmueTacos Junior Member

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    Since I posted earlier, and before I saw your message, I looked at 12v reading on the MFD in accessory mode and it was saying 12.2, 11.8 with ignition, and then 14.0 in ready. I don't know the accuracy of these as it's currently the only way I can look at the voltage.

    I also drove around a little bit to look at the 12v voltage on the MFD and had to run an errand, then the car stalled, and I am now getting the P0A78 code along with the P0A94. So...that mean the inverter is toast?
     
  11. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Maybe, maybe not. Get the three-digit info codes associated with P0A78 and P0A94. Depending on the info codes, you might get additional clues about the fault.

    Mini VCI allows visibility to the info codes. On the screen which shows the DTC, look for the little blue cloud icon. Click on that and you will see info code detail.
     
  12. ShenmueTacos

    ShenmueTacos Junior Member

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    I just ordered a Mini VCI off of Amazon. It should be here Tuesday.

    Man, I really hope I don't have to replace the entire inverter.
     
  13. bisco

    bisco cookie crumbler

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    that would be unusual. do you know the cars history?
     
  14. ShenmueTacos

    ShenmueTacos Junior Member

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    All of its maintenance was done at Toyota dealer over the years. I looked the VIN up on the Toyota Owners website before purchasing and couldn't find anything that was done to it that wasn't routine or normal.

    I bought the car at a local used car dealership back in July.
     
  15. dolj

    dolj Senior Member

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    The only thing the 12 V is suspect of is being a little low. A full charge with a battery charger will fix that.
    But more likely, possibly not. See above re just being low.
    While there might be a basis of truth to this wives tale, the reality is the battery will have to be pulled down into 8 – 10 Volt territory for this to even be a factor. Again, this line of enquiry is just a red herring.
    And all this really tells you, yet again, you just need to charge up your battery.

    Listen to the good advice from Patrick Wong. That is where you should direct your efforts.

    One last thing, @ShenmueTacos, you haven't actually said what car is the subject of this thread, although you have said it is not the 2015 that is in your avatar and I presume it is a Gen 2 as you have posted in the Gen 2 forums. What year is this Prius with 110 kmiles?
     
    #15 dolj, Oct 1, 2019
    Last edited: Oct 1, 2019
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  16. ShenmueTacos

    ShenmueTacos Junior Member

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    I own both a 2015 and 2008. I'm posting about the 2008.
     
  17. sam spade 2

    sam spade 2 Senior Member

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    Just stop it please.

    It is virtually impossible to accurately tell what voltage the various computer boards are actually getting at the moment of boot up.
    And this forum is FULL of all kinds of reports about multiple codes suddenly showing up and the cause being a 12 V battery going bad.

    And it certainly is worthy advice to first charge up a battery that appears to be a bit low.......but if it IS a bit low, there is some reason and finding that reason often is important. The battery itself is but one of several possibilities.

    Encouraging owners to chase codes pointing to systems that might require a LOT of time, money and effort to "fix" without FIRST being sure that their 12 V system is completely healthy, including loose connections. is just giving irresponsible advice.

    Nothing I have said qualifies as an "old wives tale" or a "red herring" but what you have said certainly qualifies as BAD advice.
     
  18. ShenmueTacos

    ShenmueTacos Junior Member

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    I finally have had the chance to check the sub code through Techstream and I am getting P0A94-585. A quick Google search seems to be pointing the toward the entire inverter/converter is the problem and the assembly needs to be replaced.

    A PDF I found says the DTC needs to be checked to confirm that it is indeed the problem. I assume that is something that will have to be done at a dealership?

    Anyone have any experience with this particular code?
     

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  19. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Make sure that all battery cables are secure including the negative cable where it bolts to the body. Measure voltage across the 12V battery when the Prius is READY. The voltage should be around 13.8VDC.

    If you find the voltage is substantially different, that shows further evidence the DC/DC converter has failed. if the voltage is correct then I suggest that you verify the wiring harness connections via the troubleshooting offered by the factory repair manual.
    techinfo.toyota.com

    If the wiring harness is found to be good then you would have to replace the inverter.

    The pdf you found is for a Nissan vehicle, hence it is not very useful or applicable to the Toyota Prius.

    If you decide to replace the inverter you can look for a used unit which should cost in the low hundreds. If you have the dealer quote a new unit price, the price will be in the low thousands.
     
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  20. dolj

    dolj Senior Member

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