09 Passat rear brake change

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dfiliatrault

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Good Morning all,
I have a 2009 Passat and I started changing my rear brake pads and rotors yesterday. The car is equipped with the Electronic parking brake so I ordered a Vag-com from Ross-tech to release the rear pistons. I followed all the instructions on the Ross-Tech website and it seems like the it is not working correctly. I connected the battery charger, cycled the parking brake then i ran the code to open the brakes. I then pulled the caliper off and tried to compress the piston but it would not go in. When I ran the code to open the brakes I could hear the electronic motors running and on the screen it never displays the voltage and they stop at position 7. Can anyone tell me if position 7 is fully open or should it go further I would really like to get these changes today since they are grinding right now and it is not safe to drive.

Thank you,
Dennis F.
 
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Jack@European_Parts

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How about manual lubrication of the caliper pistons for one.

Moving the stepper motors manually with voltages applied and then reversing polarity to get the response desired for basic zero setting. ( exercise them )

Please post a complete auto-scan................
 
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Uwe

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Jack: Applying voltage without limiting current in some way is risky and I personally wouldn't recommend it.

Dennis: Have you watched the video? At about 3:40 into it, it shows how to compress the piston after retracting the electronic part -- it's done with the calipers still on the car.

-Uwe-
 
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Jack@European_Parts

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In addition to the dumb glitch...........

The modules also fail, because the driver can't deal with the load requirement from what I have seen........... when the units are old and dirty/breathed on.
This can be mostly attributed to the fact there is no fuse to each motor or a sufficient circuit breaker with auto reset...probably to ref the position for wear.

Okay..............I have been doing this for almost 10 years now with success each time, and have instructed many to make a harness without incident......... saving the need for a caliper, or a module.

It saves and isolates the early crappy modules, and allows to operate the rear in tandem if needed.
It also stops the need to break the seal of motor housing, requiring a new seal through parts in most cases.

With the aid of a power probe............ which has a small fuse that pops at the slightest load........... there is no issue.
I should of stated that a fuse should be used.

Now there is an alternate mechanical method and is in the repair manual for the non electrical type personnel.

Remove the motor housing from the caliper and turn the caliper with the Torx fastener wrench manually........then compress piston as required.

In some cases the motor will turn.........however, internally has been damaged......... requiring this method above to release the unit from someone prior not doing their job proper.

I notice this is not referenced in the video and can be reviewed in section/group 46 of the repair manual.

The same issues are exhibited in rear brake calipers with combination cam e-brake mechanisms.
In other type brake systems with cables if the cam is not released by the cable being collapsed or misadjusted ( like a motor misadjusted or damaged stuck )
The caliper is damaged when someone forces the piston back mechanically, and doesn't reference the proper procedure.
In addition.........
You must clean and lube the piston before attempting to seat a caliper and before basic setting attempts.
When done preform the brake wash where needed to verify the pads and rotors are free of lubricant.

It should be noted to reference the AMP load requirements in VCDS.......... logging them when performing retractions, so that you can review the data for a sticky unit that requires attention.
 
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dfiliatrault

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I did watch the video and I had taken off the caliper off. I will try to compress the piston with the caliper on in about an hour.
 
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