HELP: Clicking in driver's side dash when cold

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Breef, Dec 8, 2016.

  1. Breef

    Breef New Member

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    Hi Everyone - first time poster, but I've been lurking for a while and really appreciate all of the comments and help that is archived here.

    Vehicle: 2006 Prius

    I've had an issue for about a year now and it's come to the point where I just can't take it anymore and would really like some help.

    Whenever it is cold (50F or below) and I press on the brake of the car there is a clicking sound on the driver's side directly under the dash behind the wheel. When braking the car tends to jerk only when this sound is present. The sound will begin before even turning on the car at all as long as the brake is being pressed.

    When you take your foot off the brake the sound completely goes away. Also, when the car is warmed up (driving for 35 min or more) in cold weather the sound will go away. When it is hotter outside (over 50F) the clicking will not occur. The car will not jerk while braking when the sound is not present.


    Here is a video that should illustrate the issue:

    https://goo.gl/photos/qVD4oEi5HKU2uq9w7 (click on the video to start it)

    I went to a mechanic once and he explained it is most likely linked to the defrost system, but I'm not sure if that is valid.

    Any and all help would be greatly appreciated. Thank you again for all of your discussion!
     
  2. andrewclaus

    andrewclaus Active Member

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    My first guess would be a problem with the stroke simulator. It's mounted on the firewall right next to the brake pedal, inside the engine compartment. Get an assistant, open the hood while it's making the noise, see if that could be it.
     
  3. Breef

    Breef New Member

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    Stroke simulator might be a good idea, thanks for the update, but upon closer inspection it appears to be just directly under the dash, as you can see when I put my hand on the area (I can feel the clicking).

    Any other ideas?
     
  4. andrewclaus

    andrewclaus Active Member

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    It's not very hard to remove the dash panels around the steering column. Google that. With components exposed, it would be easier to identify something.

    The skid control ECU looks like it might be right there on the left of the steering column. I thought that was all solid-state, but there could be a relay in there.
     
    #4 andrewclaus, Dec 15, 2016
    Last edited: Dec 15, 2016
  5. Breef

    Breef New Member

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    Thanks again for the reply. Would either the skid control ECU or stroke simulator be affected by cold weather only? Is there any type of a defrost mechanism or something that would react to cold inside the panel?

    I watched the Youtube video for removing the dash panels but I'm just not sure that even when I have identified where the clicking noise is coming from that I could identify what specific part I'll need to replace.

    Thanks for your continued replies, looking forward to your answer.
     
  6. andrewclaus

    andrewclaus Active Member

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    It sounds like it's braking-related, since you said you feel a pulse in the pedal and the noise only happens when braking. I don't know how that could be related to the defroster, but never underestimate the power of coincidence.

    If the problem is in the hydraulic system, yes, cold could definitely affect it. Cold can easily affect electronics as well, for that matter. There is a famous problem with the combination meter on the Gen 2s that occurs mostly in cold weather, for instance.

    If you can identify the clicking part, you can at least narrow down the solution. If it's hydraulic, you probably don't want to do that yourself--Prius brake hydraulics are tricky. If it turns out to be a relay or ECU, try slapping in a salvaged one from eBay or a local wrecker for $40 or so. I use this site with my VIN to investigate part locations, numbers, and prices. It takes a while to get the hang of navigating the site, but it's pretty powerful.

    Before you do much work on this car yourself, consider buying a Mini VCI cable. Lots of threads on that. There may even be pending codes stored in the OBD system for this problem. And the Mini-VCI allows the DIYer to work on the brake hydraulics. $20 for the cable, $75 for an old 32-bit laptop if you don't have one lying around.

    The blender doors for the A/C system are located in the center of the dash, I believe, as are the controls. But again, if you pull the dash panels, you'll see what it is.
     
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