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Discussion Starter #1
So I changed out the rear pads and rotors today (2002 1.8T). After reassembly the brakes work great but got the brake fault. When I was pressing the caliper back in I opened the bleeder screw. My rationale was that I would introduce some newer brake fluid into the lines rather than shove the same fluid back toward the reservoir. It also was topped off so I didnt want to overflow the reservoir. I guess in hindsight this may have been a bad idea since the fault is on now. I bled the brakes the best I could with my 8 year old son on the pedal. Like I said they feel good and work good, but are in a fault. Do I just need to rebleed them better? Could I have gotten air in the master cylinder? It is just the Brake light flashing, not the ABS light. How would one go about bleeding the master cylinder or just checking to see if there is air in it? What would even cause the STOP brake fault anyway? I know for a fact the reservoir is not low on fluid so that is ruled out.
 

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Bleeding the brake fluid must be done in a particular order of wheels. You can't just do that with one arbitrary wheel. Also check your brake sensor for not being damaged.
 

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Discussion Starter #3
Where would I find the brake sensor? I know there are sensors in the front but are there in the rear? If there is a particular order of wheels that would probably explain it. Is the particular order only on the B5.5's and not the B5's? I have done brakes many times on the B5 but this is my first time changing a B5.5, I have never paid attention to order of wheels bled before and have never encountered a problem. Also is it possible that I got air in the master cylinder or ABS from changing the rear pads?
 

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The bleeding order is the same on B5's and B5.5's.
Right Rear, Left Rear, Right Front, Left Front

I would re-bleed the brakes in the correct order to make certain you do not have any air in the lines. You also should completely flush the brake fluid every two years. On the B5.5 this is done using the bleeding procedure and bleeding 7oz of fluid per wheel.

I would see if the level sensor in the fluid reservoir is stuck. It happens. Remove the strainer and there is a "float" directly below the opening. Check to see if it is moving freely.

And the best way to bleed brakes on a Passat is with a Pressure Bleeder. Like the Motive Power Bleeder or ECS now has one as well.
 

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The cylinder bleeding order is more a matter of ensuring fresh brake fluid throughout the system, than anything else. Basically, the cylinder farthest from the master cylinder goes first- passenger rear. Now with that whole line full of clean brake fluid, the next closest, then next closest, then the driver's front. Doing this in any other order won't cause problems. By the way, opening the bleeder screw, then retracting the piston which pushes old fluid out, is exactly how I do it.

You said the brakes feel and work well. Is the brake pedal firm as normal, or does it feel mushy? If it seems OK, then perhaps the brake fault is related to a pad-wear sensor, fluid level sensor, etc.
 

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Discussion Starter #6
The pedal is firm, brakes work well, no mushiness. How do you pull the screen out of the brake fluid reservoir? I can spin it and I got ahold of it with a needle nose but cant pull it out, what is the trick to that?
 

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Discussion Starter #7
I just got rammy and yanked the damn thing out with the needle nose. The float moves freely and there appears to be more than enough fluid in there. I guess I will just try to re-bleed them and hope for the best. At this point Im still not even sure that brakes that are improperly bled will throw the brake warning light but I am hoping that is what is causing it. Just hoping it's not an electrical issue. I'll give that a try and see what happens.
 

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The pedal is firm, brakes work well, no mushiness. How do you pull the screen out of the brake fluid reservoir? I can spin it and I got ahold of it with a needle nose but cant pull it out, what is the trick to that?
Nope, wrong tool.
You need a small 3/16" thin blade standard screwdriver. Slide the blade between the edge of the strainer and the of the reservoir and GENTLY pry the edge of the strainer up. You will not be able to remove it at this point. Now hold the part of the strainer you pried up in place with your finger and walk the blade of the screwdriver around the strainer lip GENTLY prying up as you go. Kinda like opening a can of tuna. That should do the trick. Oh, by the way. Wear safety glasses and don't get brake fluid on the paint!
 

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Discussion Starter #9
Ended up re-bleeding the back brakes, got quite a bit of air out of the rear passenger one. Took probably 6 full brake pushes before all the air was out. The light was still on on though so filled reservoir and had the wife pump the brakes and bubbles rose to the top of the reservoir, had her keep pumping until bubbles stopped, light went off.
 

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Air in the system won't cause the light to be on. Looks like a sticking level sensor, or brake light switch problem.
 

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Nope, wrong tool.
You need a small 3/16" thin blade standard screwdriver. Slide the blade between the edge of the strainer and the of the reservoir and GENTLY pry the edge of the strainer up. You will not be able to remove it at this point. Now hold the part of the strainer you pried up in place with your finger and walk the blade of the screwdriver around the strainer lip GENTLY prying up as you go. Kinda like opening a can of tuna. That should do the trick. Oh, by the way. Wear safety glasses and don't get brake fluid on the paint!
This post right here deserves it's own thread and a sticky! That screen is very tricky to remove in one piece.

On topic. I've had an odd STOP Brake light issue too. I believe it was the sensor sticking. Although mine usually would stick when it was cold out.
 
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