[MertsA]

>Even in brand new cars you can replace the brakes

Just as a note, that's not always true. Replacing brake pads is one thing, but if you need to take the caliper off for service or air gets into the ABS system, you may find yourself unable to properly bleed the brakes without access to the tools needed to get the ECU to bleed the ABS system.

Depending on the car there really might not be any feasible way to complete some repair other than to have the dealer fix it. It's not even just obscure dealer only parts that other vendors don't make. When it comes to anything related to programming control modules, the manufacturers seem to want to lock this down as much as possible.

[jeremy7600]

How do you get air into a closed system? Taking a caliper off does nothing to introduce air into the system. Taking a caliper off is how you replace the pads. (still trying to square how you think it's ok to replace pads but not take a caliper off, but it may come down to interpretation, to me, taking a caliper off is not the same as replacing a caliper, since the caliper is attached to the car and needs to be detached (taken off) to swap pads (and rotors for that matter)). During the course of the average brake job, the only items in need of replacement are the pads and the rotors. Calipers only if they are sticking or in need of an upgrade. Changing brakes is not out of the realm of possibility for 99% of car owners.

I would argue any suspension parts are user servicable, engines too. The computer doesn't car if you work on the car. Those plastic covers are just to make it look good. Now diagnostics are definitely different. But you can buy a service guide, a scan-tool, and maybe a multi-meter, and you can diagnose any modern car. You could probably fix them too. The addition of the computer has not changed the makeup of a cars engine, just the addition of sensors.

I still don't see why it would have to go to a dealer. Anything related to programming control modules? Are we tuning the car or repairing it?

[MertsA]

>How do you get air into a closed system?

By disconnecting hoses or removing parts that suddenly make it an open system.

>Taking a caliper off does nothing to introduce air into the system.

No but gravity does, the brake calipers themselves actually don't move that far at all between no brake and full brake. It's only moving a tiny amount of fluid into the brake so just an air bubble or two is all it takes for the petal to go to the floor without doing much in the way of applying pressure.

>still trying to square how you think it's ok to replace pads but not take a caliper off, but it may come down to interpretation

What I meant was to totally remove the caliper from the car and disconnect the banjo bolt for the hose. As for just changing pads, you leave that alone and just remove the bolt for one slide pin and then the whole caliper flips up exposing the pads on most cars.

The concern for needing to bleed the brake system completely instead of just a bit at a wheel is if you need to do anything like replace the master cylinder or there was a leak in a wheel cylinder that was fixed but had already drawn air in through half of the master cylinder. If there is a slow leak in a hose or seal it's not uncommon for someone to never check brake fluid level and the low brake fluid sensor might not even come on if it's stuck in position over the course of 15-20 years. Even if it does someone might ignore the brake indicator light because they can still stop okay until it draws air in.

>The addition of the computer has not changed the makeup of a cars engine, just the addition of sensors.

Not too drastically but the computer still needs to know when certain things are changed depending on the vehicle. For instance, on certain BMWs if the battery under the seat is replaced, there is some kind of battery management system that needs to be reset. Failure to reset this can even cause damage to the replacement battery according to BMW. http://www.bimmerforums.com/forum/showthread.php?1355106-Why...

>Anything related to programming control modules?

"Programming" isn't exactly what I would've called it but for better or for worse, that's the terminology. You're not flashing new software on it so much as configuring it. It's as much programming as "programming" an answering machine is. With that said, let's say I need to replace an instrument panel, ECU, PCM, body ECU, etc, then I very well might need a special tool to pair it with the car. For a new ECU or instrument panel you might need to program in the VIN, mileage, emissions related settings, etc. The point being that while it's not a given that you'll need some obscure dealer only tool to do that, things are trending more and more towards that. Adding more computers and sensors is certainly a good thing in the automotive world but it can be a detriment to repairability until manufacturers start being a bit more reasonable with access to all of the firmware on a modern car.

[lttlrck]

What car for example? Flushing the brakes is easy low risk maintenance - if there is a manufacturer that's actively blocking flushing via ECU I would like to avoid them.

[MertsA]

For instance, Jeeps with ABS. It's not that the manufacturer is actively doing something to prevent you from bleeding the brakes, it's just that to properly bleed the ABS system, you need the ABS system to activate a certain solenoid while you're bleeding them. This necessarily means that something has to talk to the ECU and tell it to bleed the ABS system. The problem is that that something is proprietary tools and diagnostic equipment that the vendor has no real incentive in trying to make accessible to some small shop or the DIY crowd at AutoZone.

Flushing the brakes is fine on every car I've ever heard of. Bleeding air out of the brakes is where it can get more complicated but I'm only talking about cases where air could've feasibly have gotten into the ABS unit. So if you were flushing out some old brake fluid and you managed to drain the reservoir without noticing it, now you have air in the master cylinder and potentially the ABS unit.