How To Diagnose a Locked Up Brake Caliper and/or Dragging Brakes

In this video I’ll show you how to diagnose a locked up brake caliper and/or dragging brakes for one wheel. Usually, when brakes lock up on one wheel its caused by either a locked up caliper piston, stuck caliper slide pins, or a clogged flex hose going to the caliper. This video will give information on how to test each of these components in order to get a better idea of what is causing your brake problem.

!!Warning!! If your brakes are locked up its going to be very hot just after driving. The whole area that is affected is going to be very hot. Let the vehicle cool down before attempting to diagnose the problem. Don’t touch a hot rotor or any hot brake component! Injury can occur. An infrared thermometer would be suggested to verify that the area is cool enough to work on.

Note: This video is designed to only diagnose brakes locked up on one single wheel. If your brakes are locking up on more than one wheel this video may help you but may not help you with all possible causes of your symptom.

Also, if any air has gotten into the system during testing, which is entirely possible, then you will need to bleed the system of air. And, it should go without saying, but I’ll say it. Everything that was loosened or taken off during testing will need to be reinstalled and tightened down properly.

At about the 1:59-2:35 mark I discus how the piston is supposed to retract back into the piston bore because of a seal inside the piston bore. If the piston is seized up on the bore then this seal will not be able to pull the piston back. The test we perform by compression the piston back into the caliper is meant to check to see if the piston is seized in the caliper bore which would prevent the seal from pulling the piston back….Just in case that needed clarification.

Here are links to other great videos that may help you!

Four Ways to Collapse a Caliper Piston

How to collapse/ compress a twist in rear brake caliper

How to replace front calipers, rotors, pads and hoses

How to bleed brakes using the buddy system

Here is a link to a video that features a locked up caliper caused by a clogged flex hose:

Barbour’s Auto Help is not responsible for any damage or personal injury incurred in the process of performing any auto repairs done by you the viewer. Auto repair and diagnostics are very dangerous.
Repair and diagnose your vehicle at your own risk. It is the viewers responsibility to verify all information and procedures as outlined in YOUR REPAIR MANUAL AND OWNERS MANUAL FOR YOUR VEHICLE. Owning and using a repair manual suited for your vehicle is essential for correctly and safely performing ANY repair to your vehicle. Always wear safety glasses and heed all instructions for use applicable to any piece of equipment you may use. Also, I make no guarantee that the information given in this video is completely accurate for all situations and applications. I also make no guaranty that you will make a proper diagnosis for your problem by using this video. Use the information found in this video at your own risk.


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Comment (42)

  1. Excellent video, I love how you watch it afterwards and then go back and edit in missing information, thanks for taking the time to help everyone. One question about why in a functioning floating caliper system after releasing the brake pedal, why does the piston retract and why does the caliper slide back releasing the opposite side pad as well?
    You mention the dust boot over the pistons itself which is hard to swallow, but if that's true, why does the whole caliper slide back to neutral after releasing brake pressure?
    Would love to know
    Thanks again for such informative well explained videos!

  2. Im in a situation where im questioning weather I have a brake problem or a wheel barring problem the wheel acts mildly siezed and pulls to the drivers side. Its too hot to check right now so once it cools we will see. Hopefully its just the brakes.

  3. Please HELP. I love my '06 Toyota Solara. Wish I could bring it back to factory condition. 253,000mi. Recently I've had the front drivers side wheel freeze up when shifting to reverse. It's happened 4 times. But when shifting I heard like a hard clunk, reverse only. Then the wheel froze and not realizing it was I totally tore up the yard. I stop, put it in park then reverse again & it's fine. For the 1st time today when I pulled up to a stop sign I smelled a sort of burning smell. Just a quarter mi to my driveway & realized the wheel was smoking. It dissipated & the smoking was over. What do you think? It was just in the garage for inspection and never mentioned it & they didn't either. Should I be afraid to drive it until Monday when I can get it to the garage. It is Friday & they are gone for the weekend.

  4. I am having 2009 Hyundai sonata and front tyre got locked up randomly and give very significant burning smell. I went to mechanic shop and they said it is caliper lock, I changed the caliper and brake pad also.
    But still issue came back after 10 days, firestone check brake fluid flow and other diagnostics and found no issues.
    Issue is still not resolved, tyre locks up and gives burning smell every time specially on hot day.

    Please suggest what I can do to repair, I not not so auto savvy and cant do it by myself. Can you help me in this?

  5. I got rear breaks locked, theres a problem with the mechanism that is actionate by the handbrake cable…everytime i use the handbrakes the rear lockes. Cable is not the problem!

  6. Excellent video, my 2008 BMW 550i has been having this locking issue with the front passenger brake, when I first start driving it’s fine but after a while it begins to lock up, I believe that the flex hose is blocked and not allowing the brake fluid to release back quick enough, if I let it sit for a while it goes back to normal, I’m bringing it in tomorrow for repair so hopefully that’s the only issue, I’m pretty confident that it is just that because it’s the only one of my 4 brakes that locks up.

  7. I have an 08 Scion Xb. Since I've had it, 5 or 6 years, I've had to replace each of the rear calipers at different times. Intermittently the rotor and entire wheel would get very hot and cause the pads to smoke. Typically it happens when when I'm on the freeway at higher speeds for more than 10 or 15 minutes. Now it's happening again to one of them. One of the rear ones again. The last one was replaced less than 2 years ago, before that the first one 3 or 4 years ago. Wondering if I should replace the hoses this time too. Need advice. Thank you kindly! -Jim

  8. Replaced new caliper and it still keeps getting stuck, it’ll free up very little as I drive but I still feel the resistance of the brake , I’m guessing I have damaged brake hose ?

  9. On my 07' Volvo XC90 (12 yrs old now) , left rear brake seized up starting a fire. Replaced both rear calipers, rotors & pads. One week later, right front seized. Replaced both front calipers, rotors & pads ($600 in parts so far). Still, brakes feel as though as they are dragging. Replaced the master cylinder (another $100 + $16 in DOT 4 brake fluid). Brakes STILL dragging (somewhere). Next step … replace all 4 rubberized brake lines (another $82). Wish me luck! I hear the rubber brake lines are a far more common issue than you might think. I never thought it would be that probable. Perhaps this comment may save someone $700 in parts and a ton of aggravation. The lines are probably the cheapest and easiest item of the entire system.

  10. I have a 1987 Toyota one ton pickup chassis with a motor home built on it!!! 4 clyinder, automatic trans, rear wheel drive with a proportional valve in the back. The left fronf wheel locks up and skids. With light braking. But the truck does not stop very well!
    I put a new master clyinder on because it was leaking.. Also put a new vacuum booster. Still the front break locking up, then put new pads and calipers up fromt!!! Still not stopping. The I just put a new proportional valve and now it still locks up and hardly stops. When I bleed the brakes I get fluid out of the proportional valve. But now I don't get any fluid out of the bleeders on the drum brakes.
    What should I do????
    How do you adjust the valve????

  11. So…I replaced the pads and rotors on the rear. I noticed the drivers rear dragging after so I replaced the caliper as it seen better days and was pretty borderline anyway. Figuring it was fixed I soon noticed it wasn't. I'll take a few mile trip and all is well, I'll get back in to take the return trip and my brake pedal is hard as a rock, truck struggles to maintain speed. It's obvious that it's the drivers side rear wheel is hanging up. I let the truck sit for an hour or so and all is well again. I went and replaced the hose because I noticed no fluid was leaking out when I replaced the caliper.

    I did get fluid out of the bleeder but it seemed minimal. I figured it was because my wife was my bleeding partner and she wasn't mashing the pedal when we bled them. Later I removed the hose from the caliper all I got was a slight drip and the pedal wouldn't go to the floor. I removed it from the metal line and tried again and it went easily. I replaced the hose, bled out the air and all was well? NOPE! STILL hanging up doing the same exact thing. All good for a few miles then hard as a rock. I even went so far as to remove the parking brake shoe inside the rotor and nothing is working. I'm out of ideas. On the upside, after now tearing it apart and putting it back together 5 days in a row I'm getting quite quick at it. Any suggestions would be hugely appreciated.

    I'm wondering if it could be farther up the line like a vacuum leak at the booster line or valve or BCM but then I would think it would be on more than one wheel?

  12. What I would like to see a video on is the removal of the rubber brake hose line flair nuts without breaking the end that will need to be in place to screw the flexible brake line to.

  13. So I'm having this problem. I drove my car and the brake pads were dragging that it cause the rotors to smoke up.i compress ed the pistons back in and Its still doing the same thing. People have said to bleed the brakes but I dont see that as the problem because I didnt crack the bleeder valve open.

  14. I have a 2009 Hyundai sonata and my rear driver side tire is locked up. Won't move at all…I've had to replace 4 sets of brake pads and 4 rotors on that tire alone in the past year…would it be possible that my bearing and caliper both went bad? Or would it be something else


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