Inverter coolant changed - now ABS failed.

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by kkeane, May 14, 2015.

  1. Patrick Wong

    Patrick Wong DIY Enthusiast

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    A good point. I suggest you measure the voltage across the 12V battery when the car is IG-OFF, and when it is READY. If the DC/DC converter is working, the voltage will be ~13.8V when READY. Measuring the voltage when the car is IG-OFF will give you an idea about how well-charged the 12V battery is. A new AGM battery, fully-charged will measure ~13.0V and a battery that is discharged will measure ~12.0V.

    It is certainly within the realm of possibility that your car may have more than one problem.

    Well, the coolant pump is noisier but I would not characterize the sound as whirring. The proof of whether the pump is doing its job or not is if you see fluid turbulence in the reservoir. If you do not see this, the pump either has failed or there is air in the system.

    Yes, the skid control ECU would be quick to log a DTC reporting low voltage on the 12V bus since brake operation depends upon that source of power.
     
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  2. kkeane

    kkeane Junior Member

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    I measured it earlier with IG_OFF, and it was at 12.48V. Have to do it again in READY mode.

    Come to think about it, a couple weeks ago my wife was driving, and I was following, and I noticed that the tail lights looked very dim. So that would support your theory.

    Not just within the realm of possibility; I know of a few other problems. Those just didn't seem related, but maybe they are. Maybe the inverter coolant change just aggravated the problem to the point where it affected the ABS.

    The first problem is that one of my brakelights is near-dead (sometimes dark, sometimes just extremely dim). It actually died about three years ago, and I replaced the taillight assembly. The light went dead again fairly quickly. Checked the voltages on the tail light, and I saw 11.8V, I think. So replacing the taillight assembly a second time went on my to-do list.

    The next problem I know of is that the traction battery is discharging quickly, and charging very slowly - it spends a lot of time at a single bar. I attribute that to old age, and was going to have it rebuilt or replaced (haven't made up my mind about that yet).

    There also is an exhaust issue; when the engine is running, there is a strong exhaust smell in the engine compartment.

    I think the catalytic converter is also plugged.

    And the engine was burning quite a bit of oil, but oddly enough stopped doing that a few months ago.

    So, yes, the car has more than one problem. I'm not complaining, though; after 300k miles, that's not surprising.

    Regardless, on Saturday I'll try your bleeding suggestion and also measure the voltage with IG-ON. That should give me more information.
     
  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Regarding the near-dead brake light, check the ground connection to make sure it is tight.
     
  4. kkeane

    kkeane Junior Member

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    Will do, thanks. All the other lights in the tail light assembly are working fine, though, but you may still be right - possibly, the LED is more sensitive to a poor ground connection.
     
  5. kkeane

    kkeane Junior Member

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    There goes another theory. The voltage across the 12V battery is normal - around 12.4V in IG-OFF, about 13.8V in IG-ON. I won't rule out that the voltage drops during my uphill mountain climbs due to the bad traction battery, but the ABS reports failing even with the normal voltages.

    I haven't been able to bleed the inverter coolant yet; the vinyl tubing I have turned out to be too big.
     
  6. JC91006

    JC91006 Senior Member

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    I don't think you have to lead the vinyl tubing back to the reservoir, that's just so you don't waste the coolant. If you have a bigger tubing, just lead it downwards to the ground or into a big cup. Add to the reservoir as it gets lower and lower.
     
  7. SageBrush

    SageBrush Senior Member

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    Stressing your inverter with an inadequate cooling system is not smart, unless you are looking for an excuse to buy a new Prius.
     
  8. kkeane

    kkeane Junior Member

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    No, it's the diameter; the tubing I have doesn't fit onto the bleed valve itself. I'm thinking about simply using a straw for that purpose, but it wouldn't allow me to see the air coming back in.

    Agreed. That's why I'm trying to work it out.
     
  9. SageBrush

    SageBrush Senior Member

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    Yoda impressed, is not.

     
  10. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Actually, I don't bother to use the vinyl tubing. I just open the bleed valve and watch the flow of coolant - and close the valve when there are no air bubbles in the coolant.

    As JC indicated, the purpose of the tubing is to avoid spilling the coolant on the ground. Only a few ounces need to come out of the valve so it is not the end of the world to lose that coolant. However you should hose down the driveway with water so that no local fauna is tempted to drink the coolant which is poisonous.
     
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  11. kkeane

    kkeane Junior Member

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    I think with the inverter coolant pump, I may have been chasing a goose. I had seen some waves in the reservoir and assumed that they were simply from the vibrations from the ICE. Turns out that these waves were still there even after the ICE shut off, so it was my lack of experience that failed to see the turbulence.

    I also did try the bleeding valve with a simple straw. Worked fine. The result is that there were a few tiny air bubbles, but very few of them (I think I only counted two larger than a millimeter, and one that was a fraction of a millimeter, during four or five iterations). Interestingly, the bleed valve was solidly seized up; I don't think the shop bled the system - they probably instead used one of the vaccum devices I read about. Regardless of how they did it, it looks like they did get the air out of the system just fine.

    Also, I don't hear anything that looks like air in the coolant pump. When I go IG-ON, I do hear a whirring sound (the same one I always heard, nothing that sounds abnormal). In the past I had always assumed that it was some fan, but it might actually be the coolant pump. I also added a tiny bit of coolant so it is now at the full line slightly above the seam in the reservoir, and a little easier to see the level. I still don't see the level rising towards the front, but it looks like the inverter cooling system is in fact working as it should.

    I also felt the hose leading to the inverter coolant reservoir, and felt some vibration, as if fluid is going through it.

    So, bottom line: voltages are normal at least with the car parked and the traction battery at two bars, no air in the inverter coolant system. I don't see the turbulence, but that might be me, rather than the pump. I suppose at this point I have to conclude that there probably was nothing wrong with the work the shop did, and my problem is probably unrelated. That is all I set out to determine.

    Thanks, everybody, for your help!

    Of course if you have any more idea for things I could investigate or fix with my DIY tools and (lack of) experience, I'd appreciate it. The more of the labor I can do myself, the cheaper the car maintenance will be!
     
    #31 kkeane, May 16, 2015
    Last edited: May 16, 2015
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  12. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Thanks for the update. If you intend to continue DIY, the next step is to purchase Mini VCI so you can retrieve the DTC logged by the skid control ECU.
     
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  13. kkeane

    kkeane Junior Member

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    Oh yes, thanks for reminding me of the DTC. The Mini VCI seems like a good investment in any case.

    I was able to retrieve the codes with the jumper method earlier. The codes I retrieved were:35 for the (!) light, 42 for ABS and 45 for VSC.

    By any chance, do you know where I could find a list of what these codes actually mean?
     
  14. ChapmanF

    ChapmanF Senior Member

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    You'll find them in the diagnostics volume (that's vol. 1) of your service manual on techinfo.toyota.com. It's not the sort of information that translates well into list form. Somebody's always trying, so you might well find a list somewhere that says

    42 TURBO ENCABULATOR UNDERVOLTAGE

    or the like (or, you'd see it display like that on a scantool), but that almost never helps you any. (Or, the sort of person who thinks a "list of what the codes mean" is the last word would see that entry, immediately spend $BIG on a new turbo encabulator, then wonder why the problem's not fixed.)

    When you look the code up in the manual, you see it listed with the starting page number of the workup section for that code. In that section, you'll find out what exact conditions cause the computer to log that code. (It can't just psychically know the encabulator voltage is wrong, it has to be measuring something, and when you see how it does that, you also begin to see what other things could possibly be wrong that would result in the same code being shown.) Then you can follow through the workup steps in that section to step-by-step rule out the possibilities for why that code came up, until one remains.

    (In another post I covered one concrete example of how the computer actually monitors just one of the components in the Gen 1 brake system; that post is here. It's the wrong generation and may not be the source of your problem, but a good example of how the codes from the computer make the most sense when you can see exactly what the computer looks at to produce them.)

    -Chap
     
  15. kkeane

    kkeane Junior Member

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    Thanks, Chap. Completely agreed on the codes only being a starting point for troubleshooting. I'm an engineer by profession (mostly software, some hardware), so I can completely relate!

    Wouldn't that still be true with the MiniVCI, though?
     
  16. kkeane

    kkeane Junior Member

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    Thanks for the tip! The ground connection looks good, unfortunately. I unplugged the wiring harness from the taillight assembly and measured the resistance against the car body (I used one of the screws in the cargo compartment). The brown wire (I believe that is ground) showed around 2 Ohms.
     
  17. ChapmanF

    ChapmanF Senior Member

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    Exactly. The Mini VCI will give you the five-alphanumeric code and that might cover a slightly narrower stretch of ground than the two digit blinky, and the Mini VCI will probably give you some one-liner code translation like the example I gave above, but still your next step really is to flip to the corresponding workup section in the manual and proceed with your diagnosis from there, not to puzzle over the six words on the Mini VCI screen as if they were some oracular pronouncement. :)

    -Chap
     
  18. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Although it is true that the skid control ECU will report two-digit blink codes, I discourage relying upon those because many of the codes are undocumented. Of the three that you reported, only "35 for the (!) light" is documented, and it means that the stroke simulator or the skid control ECU are defective. I would confirm that using Mini VCI before taking any action since neither of those are minor repairs.

    Well, a resistance of two ohms is not great. Make sure you have accounted for the resistance of the test leads by shorting them together to see what the reading is. Then subtract that baseline reading from whatever other resistance tests you do.

    Suppose you are starting with a voltage of 14V, and the current in the circuit is 4A (required to power both of the tail light assemblies). A resistance of 2 ohms will result in an 8V drop across the resistance, so the remainder of the circuit is left with 6V. That is a highly significant voltage decrease.
     
  19. kkeane

    kkeane Junior Member

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    Thanks for the warning about the blink codes. I think it's time to take it to a shop at this point... Bracing myself for a fairly major bill.
     
  20. northwichita

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    I still wonder about this issue, that you may still have a air pocket causing less fluid flow . Do you know someone with a similiar model Prius you could compare it with? I looked up youtube videos, but it doesn't video very well.
     
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