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C1249 code and randomly activated warning lights

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Kristen678, Aug 15, 2020.

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  1. Kristen678

    Kristen678 Junior Member

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    Hello all -
    I recently started getting a series of warning lights after a mechanic, during an oil change, attempted to reset a TPMS light. The lights that come up are Parking Brake, ABS, and Traction Control. I got a code reader (VEEPEAK) and used the Garage Pro app (Torque Lite didn't seem to work and Dr. Prius is only for batteries). The code that came up is C1249, Open in Stop Light Switch Circuit. The lights don't always come on and when they do, it isn't predictable. There's a quick lag when they come on that feels like the cruise control coming off but that may be a safety feature. When the lights are off, I am still able to get the fault reading using the code reader. Without the warning lights on, my brake lights work - I don't know if they work when the warning lights are on.

    I was going to replace the brake lamp switch but I couldn't remove the lower panel. I've now started thinking that, since the warning lights aren't always on, it may not be the switch at all but something else like the wiring or speed sensor. I'm a novice to this stuff so any help is enormously appreciated! I've been playing it safe and not driving far but honestly, with the pandemic, I'm getting really stir crazy and antsy so I'm very motivated to fix the problem as soon as I can.

    Thoughts?
     
    #1 Kristen678, Aug 15, 2020
  2. ChapmanF

    ChapmanF Senior Member

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    That's not a code that gets discussed here a lot, so I'm not sure how much PriusChat wisdom there's going to be.

    Have you looked in the repair manual yet? (more info) It will have a whole section for each code, including that one, that will give steps you should follow to find out why you have it and what to do about it.
     
    #2 ChapmanF, Aug 15, 2020
  3. JC91006

    JC91006 Senior Member

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    You can find youtube videos that can help you remove the panels on the car. Look up how to replace the MFD on a Prius, it involves removing all the same pieces.

    The stop light switch is not a common failure, but I've experienced that myself. After replacement of the switch (I just bought a used OEM switch), it fixed the problem. It's a tight fit for your hands under the dash area, but it's not too bad
     
    #3 JC91006, Aug 15, 2020
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  4. TMR-JWAP

    TMR-JWAP Senior Member

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    I have also seen this code be present several times with a P0A93 inverter cooling water performance code, yet I've never had to replace the switch and the code never returned after installing a replacement cooling pump.. I've often wondered if an inverter cooling pump starting to fail electrically (drawing excess current) is somehow triggering the C1249 code when the current increase causes voltage in the circuit to drop but isn't high enough to open the 15 amp fuse. I only see about 50% of the pump failures pop the AM2 fuse. The others just eventually burn the electronics in the pump and the pump stops working. Then at some point later, minutes or weeks, depending on how the car is driven, the P0A93 shows up.

    With my curiosity peaked again, I just looked up that code in one of my manuals (not Toyo) and it mentioned it could also be triggered by a intermittent brake light. Might be worth checking out before digging into the dash. Unfortunately, the brake light portion is LED and makes it to where the entire assembly has to be replaced if it fails.

    Perhaps the DTC Guide will help...
     

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    #4 TMR-JWAP, Aug 15, 2020
    Last edited: Aug 15, 2020
  5. Kristen678

    Kristen678 Junior Member

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    Thanks everyone!!
    ChapmanF - I don't have a repair manual but I just remembered seeing that my library has vehicle manuals. I'll check to see if they have one I can check out (literally).

    JC91006 - I followed your advice and went down the youtube rabbit hole but I don't have the tools I need to ensure that I don't bust a panel clip. :/

    TMR-JWAP - you definitely know a lot more about the cars than I do! Based on new info, I don't think it's the pump. :)

    Since I couldn't get into the lower panel area and the warning lights don't come on often, I was in a holding pattern but this morning they went off and I was able to verify that the brake lights aren't staying on. When I hit the brake, only the brake light in the hatchback activates - the others don't come on. When I remove my foot from the brake, it goes back off. I restarted the car to remove the warning lights and repeated the process and found that the problem is always happening. I think this eliminates a few of the other options and brings me back to the brake light switch but I haven't seen anything about it failing in this way...I've only read about it causing the lights to always be on. Can anyone confirm?

    Thanks again, I really appreciate it!!
     
    #5 Kristen678, Aug 19, 2020
  6. dolj

    dolj Senior Member

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    FYI, you might want to link your other thread back to this one and just run with one. It is less confusing and avoids double-ups of information.
     
    #6 dolj, Aug 20, 2020
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  7. Tideland Prius

    Tideland Prius Moderator of the North
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    #7 Tideland Prius, Aug 20, 2020
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