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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.

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  1. av8erdunn

    av8erdunn Junior Member

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    Well I changed my 12v battery to a yellow top optima a week ago cause my other battery crapped out on me and the car had to be towed home. (see thread here fiinally pulled my DTC's | PriusChat

    Tonight she was stopped and lights showed back up as before but without the big red triangle. I pulled the codes and this is what I found.

    As always help is greatly appreciated. I need a reliable vehicle, I half thinking about trading in on a prius v if this keeps up.
     

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    #1 av8erdunn, Dec 23, 2014
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Make sure that the battery cables are tight, especially the negative cable where it bolts to the body.

    Then, use a digital multimeter to measure voltage across the 12V battery:

    1. When the car is IG-OFF. If less than 12.6V, put the battery on a charger now and fully-charge it overnight.
    2. When the car is READY. If less than ~13.8V, you have a problem with the DC/DC converter within the inverter.
     
    #2 Patrick Wong, Dec 23, 2014
  3. av8erdunn

    av8erdunn Junior Member

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    I just load checked the battery and it load checks fine. With a multi meter ign off I am reading 13.0v with it ready I tead 14.1v. Negative is tight at battery, I will check body bolt.

    Edit: Body bolt is tight and I made sure terminal was TIGHT.
     
    #3 av8erdunn, Dec 23, 2014
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The voltages you measured are good.

    Regarding DTC C1241, check the ABS 1 and ABS 2 relays. "Check" means that you find and remove the relays, one at a time. Use an ohmmeter to identify the relay coil terminals, the resistance will be ~100 ohms or so. Apply 12VDC to the relay coil terminals. Measure resistance across the switched terminals when the relay is energized. If the resistance is more than 0.5 ohm (after accounting for test lead resistance) then replace the relay.

    If the relays are good, was the car in a rear-end accident that would have damaged the brake power supply (the large black rectangular box located next to the 12V battery) or its wiring harness?

    If you don't find an obvious problem and wish to continue the DIY process, I suggest you subscribe to techinfo.toyota.com so you can follow the troubleshooting tree which involves measuring voltage at the brake power supply, verifying the wiring harness, etc.

    Regarding DTC C1249, that indicates a problem with the brake light switch, the wiring harness, or the brake light LEDs. When you depress the brake pedal, do the brake lights work?
     
    #4 Patrick Wong, Dec 23, 2014
    Last edited: Dec 23, 2014
  5. av8erdunn

    av8erdunn Junior Member

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    Why would the c1241 be a relay considering it says low or high battery voltage? I'm willing to check anything but I like to understand the reasoning behind checking something. The car hasn't been involved in an accident so that's unlikely and both brake and tail lights are working. It seems like once this thing hit 190k and the 12v battery started going bad its been a problem. I'm gonna look at the tech site now. I like to do my own maintenance as I really don't trust most mechanics to work on my cars, boats and airplanes.

    I am also wondering if the c1241 may be a residual code from when I changed the battery? I'm not sure if I ever cleared them after the tow home. I'm thinking so but the only reason I don't know is because it states the speed as 37mph. She was sopped at a light when the dash lights came on tonight which shows on on c1249. The only other thing I wonder is if it could throw the c1241 and not actually show that its thrown one.

    Thanks for the help.

    Looking at the tech site, which package comes with the troubleshooting tree you mention? Standard or professional diagnostic? Does the site help you use the tech stream software to its capabilities? I can use it but I know it can do a lot more than I'm using it for.
     
    #5 av8erdunn, Dec 23, 2014
  6. bisco

    bisco cookie crumbler

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    how many miles on her?
     
    #6 bisco, Dec 23, 2014
  7. av8erdunn

    av8erdunn Junior Member

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    #7 av8erdunn, Dec 23, 2014
  8. Patrick Wong

    Patrick Wong DIY Enthusiast

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    DTC C1241 is logged by the skid control ECU. That DTC means that there is abnormally low battery voltage present at that ECU.

    The ECU receives voltage via the ABS 1 and ABS 2 relays, hence it is necessary to verify proper functioning of those two relays.

    The minimal techinfo package, $15 for two business days, will provide access to the repair manual info you will need. I suggest you do a search in the repair manual text for the DTC logged by your car. Also look at the electrical wiring diagram for the skid control ECU so you can develop a full understanding of the issue.

    You can try clearing the DTC to see if they will return or not. However since you reported that the warning lights appeared only after a period of time had elapsed, then the DTC are likely the result of a current problem.
     
    #8 Patrick Wong, Dec 23, 2014
    Last edited: Dec 23, 2014
  9. av8erdunn

    av8erdunn Junior Member

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    That makes sense. I will try to diagnose it further this afternoon after the wife gets off work. I have since cleared it to see if it's going to come back which I'm sure it will.

    Thanks for the help
     
    #9 av8erdunn, Dec 24, 2014
  10. av8erdunn

    av8erdunn Junior Member

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    I checked the relays and they are fine. I remember about a week ago I heard a grinding noise that i never heard before as I was coming to a stop. I immediately tried to recreate the noise many times but was unable to get it to do it again. I'm not sure if this has anything to do with the codes but I figured I throw this out there just in case.

    Also another question, in one post you mention the code being caused by brake control module then the other you mention the skid control module that abs1 &2 supply voltage to that could cause the code. Can it be either of them? Just want to be sure I'm not looking in the wrong places.
     
    #10 av8erdunn, Dec 24, 2014
  11. av8erdunn

    av8erdunn Junior Member

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    Does the code point to the skid control or the brake module?
     
    #11 av8erdunn, Dec 26, 2014
  12. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The DTC is logged by the skid control ECU because the 12V bus is measuring low as viewed by that ECU.

    So the question is, why is the voltage low? It could be due to several reasons: the ABS 1 and ABS 2 relays, the brake power supply which is the black rectangular box near the 12V battery, the wiring harness that feeds the skid control ECU, or the ECU itself.
     
    #12 Patrick Wong, Dec 26, 2014
  13. nh7o

    nh7o Off grid since 1980

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    That may have been the brake discs getting cleared of rust. If there is salt on the roads I would think they could rust up over a short period, but would get cleared on the first brake press.
     
    #13 nh7o, Dec 26, 2014
  14. av8erdunn

    av8erdunn Junior Member

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    There wasn't salt on the roads around here and the car had been driven about 200 miles that night prior to the noise.

    I have driven about 250 miles so far and the codes have not come back. I check it every afternoon to see if there are pending codes or anything. I'm going to keep an eye on it to see if it happens again. I'm hoping it was just a fluke.

    Thanks for the help and I will keep yall posted to if it returns.
     
    #14 av8erdunn, Dec 26, 2014
  15. Patrick Wong

    Patrick Wong DIY Enthusiast

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    If the problem returns, I would suggest replacing both the ABS 1 and ABS 2 relays. That would probably cost ~$150 in parts.
     
    #15 Patrick Wong, Dec 26, 2014
  16. av8erdunn

    av8erdunn Junior Member

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    Even after checking them and they checked ok?
     
    #16 av8erdunn, Dec 26, 2014
  17. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Assuming the problem returns after some trouble-free period of time has elapsed, and considering the possible causes, the most likely cause of an intermittent issue would be a relay.

    Another possibility would be wiring harness damage due to rodent infestation. You'll have to determine how likely that scenario is.
     
    #17 Patrick Wong, Dec 27, 2014
    Last edited: Dec 27, 2014
  18. av8erdunn

    av8erdunn Junior Member

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    I see!
    As for rodents, I think that is a slim to nonpossibility. I have lived here for 25 years and we have never even seen a rat nor had any damage to our vehicles due to infestation .

    I really appreciate all your help..
     
    #18 av8erdunn, Dec 27, 2014
  19. av8erdunn

    av8erdunn Junior Member

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    Well so far the codes have not shown themselves again. Keeping my fingers crossed it stays that way. Then the only thing that puzzles me is what caused them to show the first time. I'm leaning towards the relays as you stated.

    Just wanted to give an update.
     
    #19 av8erdunn, Jan 2, 2015
  20. av8erdunn

    av8erdunn Junior Member

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    Well I spoke too soon but this time the codes are different (though it flashed the cruise before but not since changing battery). The wife had been using the cruise for about 5 minutes; she pulled to a stop light and the cruise light started flashing. I am at a loss with this thing :( .

    Any ideas what the problem may be now? I am going to get on Toyota tech but with so many codes I feel like I will be chasing my tail.
     

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    #20 av8erdunn, Jan 5, 2015
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