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Discussion Starter #1
I bought a 2009 smart ForTwo sight unseen. It was a good price and I was willing to take the risk. When I got the car and I took it for a drive the triangle light came on and the car went into limp home mode. I could feel the brakes were dragging. The pedal keeps getting stuck in the down position and if I pull it back up with my foot the car drives fine. At first I was thinking maybe seized calipers but I feel like in that case pulling up on the brake pedal wouldn't fix the issue.

The car also had a code for the brake light switch. I got a new one from the dealer and I replaced it but that didn't fix the issue. I didn't think it would but it was worth a shot since it was throwing the code.

Any idea what it might be?
 

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If your brake pedal goes down but not back up, there is a major brake fluid problem. Could be a ton of air in the system, really bad master cylinder, bad calipers or broken brake lines. It’s a major safety issue and you should not drive it until it’s fixed.

Once the brake pedal returns to the proper travel, the brake switch issue should go away.

If the brakes really are dragging, the pads might have come separated from the backing plates (had this happen and the brakes and drums for insanely hot). This wouldn’t cause the issue with the low pedal travel, but you really need to check everything. If it happens, it can cause the seals in the caliper cylinders to fail and boil the brake fluid. The entire system should be emptied and re-bled.

If you have access to a Mercedes Star diagnostic machine, you can get the fault codes that should point you into the correct direction to fix the problem.
 

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Discussion Starter #3
I don't have access to star diagnostics. I was planning to bleeding the brakes tomorrow and see if anything improves. Will inspect the pads and rotors while I'm doing that as well.
 

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Perhaps a sticking piston. Would explain why you have to pull up on the pedal. Be interesting to see what you discover.
 

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You best bet, have a complete brake job down on your car. You didn’t mention the vehicles mileage. New rotors, front pads, the rear drums might still be good. They will bleed the brake lines, check your ABS system. Power assist.

Not sure why you car, went into limp mode. How that relates to the brakes. That would be a engine issue. You don’t need a star diagnosis system, on a brake system. Any one can pull the codes on a smart car.

good luck.
 

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I would never throw parts at a problem until I knew the cause. Maybe it needs new brakes, but the symptoms you mention don't typically indicate that the rotors/pads are bad. I never change my brakes until they approach the factory minimum. Stuck piston, clogged hoses, bad master cylinder maybe. If it is any of them, new brakes won't help a bit.

Len
 

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I would never throw parts at a problem until I knew the cause. Maybe it needs new brakes, but the symptoms you mention don't typically indicate that the rotors/pads are bad. I never change my brakes until they approach the factory minimum. Stuck piston, clogged hoses, bad master cylinder maybe. If it is any of them, new brakes won't help a bit.

Len
your the only one that appears to know what they're talking about. it's a master cylinder
 

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Master cylinder has a booster. If the pedal doesn't come back up by itself, you have a master cylinder, booster or pedal linkage problem.
Sezied pistons will not cause that.
My guess is the booster if the mechanical linkage to the pedal is ok.
I have a complete assembly from a 2015 with 10k if you need one.
 

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Discussion Starter #10
Pads and rotors are good. Bled the brakes (fluid was in good shape, didn't notice any air) but it did get better for a little while but went back to having the same issue. The only other thing I noticed was that the boot on the right front caliper was torn a little. When I replaced the brake switch I lubricate the brake linkages. I'm also thinking more likely something to do with booster/master cylinder. The calipers moved smoothly and didn't seem seized.
 

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All the hoses were in good shape from what I could see. No pinched or torn hoses.
Unfortunately you can’t see inside the master cylinder to determine if something is wrong there and you can’t see inside the brake hoses to determine if a piece of rubber on the inside diameter of a hose has become delaminated and is acting like a check valve. Hoses may look fine on the outside but have issues inside. Been there, experienced that.
 

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Discussion Starter #13
Well I changed the brake hoses and bled the brakes again. The car is MUCH better but if I drive the car in the city for 30 mins or so I’ll have one episode of the pedal getting stuck down. I’m not talking getting stuck down all the way to the floor. It’s just down about an inch or so. As soon as I pull back on the pedal the car drives fine again. The pedal being down causes the brakes to drag.
 
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