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More codes after changing 12v battery a week ago

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by av8erdunn, Dec 23, 2014.

  1. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The reoccurrence of DTC P0607 is troubling. How likely is it that the replacement HV ECU has a problem? This is very strange.

    The left and center brake lights get their power from the same source as the right brake light. 12V power goes through the 7.5A STOP fuse, then through the brake light switch. There is a junction connector which connects the three lights together. Maybe that connector is having a problem. Also check the ground connections for the lights. I don't think this problem is related to the HV ECU, but it may be indicative that the vehicle wiring harness is starting to get flaky, and if so that would be one reason that the car would eventually end up in the salvage yard.

    Mobile, AL current weather shows 100% humidity. That may be part of the problem with the wiring. Has the car ever suffered flood damage?
     
    #61 Patrick Wong, Jun 16, 2015
    Last edited: Jun 17, 2015
  2. dolj

    dolj Senior Member

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    I'm a bit perplexed; these two codes seem to go together:

    C1249 Open in Stop Light Switch Circuit
    P0607 Control Module Performance (in CC section)

    I think Patrick is sort of on the right track. My interpretation of these two codes is that the control module is not able to function correctly as it is getting bad data from the brake switch. I'd be looking at the brake switch a bit more closely and be doing some diagnostic testing there. It wouldn't be the first time a brake switch went bad. Focus also on the junction connector which connects the three lights together mentioned by Patrick.

    There again, I could be completely off track.
     
  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    In post #33 the OP says he replaced the brake switch.

    Since the car worked OK from January to April, I am wondering whether the issue might be climate-related, which would imply flaky/intermittent wiring. The OP lives in an area that is currently showing 100% humidity on weather reports.

    The wiring diagram shows there is only one connection from the brake light switch to the HV ECU so if the two processors within disagree about whether the brake pedal has been depressed you would think the intermittent fault has to be internal to the ECU.

    So I guess if I were the OP I would buy yet another ECU to see what happens. His experience has shown that the first used ECU was definitely faulty since he could not configure it to operate. Could it be that his original ECU and the second used ECU both have an intermittent connection within which is causing the two ECU processors to be out of sync?
     
    #62 Patrick Wong, Jun 17, 2015
    Last edited: Jun 17, 2015
  4. dolj

    dolj Senior Member

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    You have a better memory than me, Sir. That is a few posts back.

    But I guess it is possible that the brake switch has developed a fault since, though.
     
  5. av8erdunn

    av8erdunn Junior Member

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    The car doesn't show any of the typical signs of having been in a flood before nor did the car fax come back with anything. I will look into the light problem this weekend but as for another ECU I can try it but whats the chances of getting 2 bad ECU's in a row. From what I can gather the ECU problem is a fairly rare problem. You make a good point as far as humidity having a factor on this problem. Now that we have HIGH humidity every time she drives it the lights will come on.

    Brake switches are cheap too!!! I might go ahead and replace it again just to be sure.
     
  6. Beachbummm

    Beachbummm Senior Member

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    dim and flickering tail light sounds like a bad ground wire...check the wires going into the hatchback from the roof..i had a ford wagon with tail light issues no one could find, turns out the wires had pulled apart inside the black covering from the body to the hatch back..look for breaks and see if the wires have pulled out of the connectors ..
     
  7. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I actually don't think the brake switch is the problem if at least one brake light is working correctly.

    Regarding another ECU, if you buy another used one you might try to get one from a 2008 or 2009 model year, from a part of the country that does not experience such high humidity.

    Your car is 9 years old, I understand you've owned it for more than 2 years based on one of your prior posts. That post has a picture which shows the same DTC that your car continues to log as of yesterday, so there has been no improvement despite your efforts.

    Are you able to return the used ECUs that you have already purchased? If not, you might be interested to open one up if the covers are not too hard to take off. Use a bright light and magnifying glass to inspect the solder connections around the two processors if you can find them. Look for two integrated circuits that have the same part number, which have a relatively large number of connections leading to them.

    You would be looking for any cracks in the solder connections, or solder that looks dull or pitted.

    I do not recall very many owners complaining about P0607 so this issue is pretty rare.
     
    #66 Patrick Wong, Jun 17, 2015
    Last edited: Jun 17, 2015
  8. av8erdunn

    av8erdunn Junior Member

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    I am actually able to return both of the ecu's so tearing into them isn't a possibility. Yes I have had the car for almost 2.5 years now with this happening for about the last year or so. I am actually at a loss as to what to do. I know if I take it to the stealership they are going to want to replace the ECU since that's where the codes pointing to. I am going to try to fix the brake light problem and see if that has any influence on whets going on. Not likely but I am keeping my fingers crossed. It might be time to get the wife another vehicle. :(
     
  9. av8erdunn

    av8erdunn Junior Member

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    Another odd problem I just thought about. Sometimes when you are slowing down I get a grinding noise coming from the brakes as I am slowing. Pads are good and rotors don't show rust. Just trying to think of any other factors that may be contributing.
     
  10. valde3

    valde3 Senior Member

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    Have you looked at the inside of the brake discs? If brakes wear one side more than the other your caliber sliding pins need lubrication.
     
  11. av8erdunn

    av8erdunn Junior Member

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    Pads are wearing evenly and rotors are in great shape.
     
  12. av8erdunn

    av8erdunn Junior Member

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    Thinking about what you said in regard to it being climate related, I wonder if heat has anything to do with it. Ever since we started getting in the high 80's to low 90's it happens every time when its that high. This morning when she went to work the lights didn't come on.

    Just a thought!!
     
  13. av8erdunn

    av8erdunn Junior Member

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    What's the chances that I need to replace the brake pedal stroke sensor? Would that cause the p0571? Also when I replaced the brake switch I went with an aftermarket unit. That shouldn't matter but what's your thoughts?
     
    #72 av8erdunn, Jun 17, 2015
    Last edited: Jun 17, 2015
  14. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I do not think the stroke sensor is at fault.

    The brake light switch consists of two separate switches. One switch is normally open and the other is normally closed. Then when you press the brake pedal to activate the switch assembly, the normally open switch will close while the normally closed switch will open.

    The HV ECU expects to see 12VDC coming from one of those switches at all times. If it gets 0 voltage from both switches then it assumes the switch assembly has failed.

    You can test the switch assembly by measuring resistance across the two switches, then pressing the brake pedal to confirm that they work (or else find they do not work).

    I am not a proponent of buying aftermarket parts in general. However since you already bought the switch assembly, I suggest that you test it if you are concerned about its functionality.

    I have a suggestion for something else that you can try: Buy a can of electrical contact cleaner spray at the Walmart auto chemicals aisle, or your local discount auto parts store. Remove the brake light switch wiring harness connector and spray the connector and the switch terminals. Have a paper towel available to catch the overspray and the cleaner dripping off. After the cleaner dries, install the wiring harness connector. Also remove the wiring harness connectors from the HV ECU and spray the connectors and the mating terminals on the ECU.

    Do not use a cleaning product other than electrical contact cleaner. If for whatever reason you cannot obtain this product locally, use isopropyl alcohol which you can get at any drugstore. I use this in 91% strength, to clean electronics parts and printed circuit boards.

    After testing the brake light switch and cleaning the terminals, if the HV ECU still logs the brake light switch fault code, another test is to measure voltage at the ECU wiring harness pins which relate to the two separate switches, using the electrical wiring diagram to identify those pins. When the car is READY, measure voltage at those two pins. One of the two pins should measure ~12VDC when the brake pedal is up, and the other should measure that voltage when the pedal is depressed. If the voltage measurements are correct but the ECU logs the fault then you will know the problem is with the ECU. If the voltage measurements are not correct then there may be a fault with the wiring harness. This assumes that the fault is solid - if it is intermittent then the fault may not appear while you are testing.
     
    #73 Patrick Wong, Jun 17, 2015
    Last edited: Jun 18, 2015
  15. av8erdunn

    av8erdunn Junior Member

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    I will try that this afternoon(hopefully if time allows). When you say it consist of two switches, you mean its basically two switches contained in one unit. Right? Beacause I only changed one button switchfor the brake lights. Also I was just thinking in the drive in this morning, if my brake light switch isnt ajusted appropriately and the pedal sensor is seeing movement but lights arent coming on would that cause a fault? Just brain storming here.
    Thanks again for hanging in there.
     
  16. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Yes, the one brake switch assembly contains two switches inside. There should be at least four wiring harness terminals.

    The adjustment spec is 0.020 to 0.095 inches of clearance between the brake light switch and the area of the brake pedal which contacts the switch. I don't know what would happen if the switch is not correctly adjusted.
     
  17. av8erdunn

    av8erdunn Junior Member

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    Well I'm pretty sure I found out what happens when its not adjusted correctly. I adjusted it to the upper limit of .095 and no lights have come on since adjustment where they were coming on every drive. I think the stroke sensor was seeing movement and it was faulting out because the brake light switch wasn't coming on until later in the pedal depression.
    Keeping my fingers crossed that they don't come on again but I feel certain that it solved it.

    Thanks for hangin in there and trying to help me fix it.
     
    Patrick Wong likes this.
  18. bisco

    bisco cookie crumbler

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    all the best.(y)