Replacing Rear Calipers with Electronic Parking Brake Motors
Chase: A lot of new cars today have an electronic parking brake. What's most crucial is understanding if you have an electronic parking brake. And to do that, just go inside the car, see if you have a switch or a button to apply the brakes. You can also see if it has an electronic parking brake module that actually drives the cable. Or you can just come back to the rear wheels here and look and see if it has a motor on the back of the caliper here and it just runs in and out and applies the parking brake. Now, when servicing, new rules apply.
John: Now, our vehicle has the electronic parking brake with the switch Chase had mentioned. You don't see any hand lever in here or you don't see any foot lever that is going to activate it because it's electronically activated. It's really just as simple as coming over here, pulling it up. It engages it. And then if you want to disengage it, you have to put your foot on the brake and then push it down and now it's disengaged. That's the parking brake assembly.
Now, we wanted to go into service mode. That's the most important thing. And Chase talked about that a little bit earlier. Every vehicle is different, so I can't stress enough to go to your vehicle's service manual and find out the manufacturer's specifications and procedure for putting it into service mode. Some cars go into service mode by pushing the button several different times. Some cars may require a battery charger on the actual system so it doesn't drop a little voltage, and that can cause some major damage. Not only with the caliper, but with some of your components and your hands and stuff in the way of when you're doing a brake job. You don't want that to actuate.
Also, some cars... you may have to use a scan tool. And in a scan tool, you may just go into the parking brake app, go inside that. Go ahead and use that and disable it that way. Now, our car? Well, there are several methods you can do it. And you can take a look at this graphic. It kind of shows what you can do. On this car it says you can use a diagnostic scan tool and/or you can go into the Uconnect cluster and when we go into the cluster, we are actually going to hit some displays and show you how to do it. But before we do that, let's read this together. This is so important. "If the electronic parking brake switch actuator, the calipers move from the bracket and still connect electrically, the EP, which is electronic brake motor, will fully extend, causing damage to the caliper piston. Disconnect and isolate the negative battery cable before servicing any EPB connectors."
So on this car, they want the battery disconnected and then we can go through the sequence. So, that's hugely important.
Now, to go to the sequence, it's pretty simple. You just come up to the Uconnect and you go into the settings. I'm going to push settings. And once I push settings, we can go down. Scroll down. You see there's brakes right there. So simply just click the brake icon and then we got brake service mode. If you click brake service mode, what's going to happen... it says do you want to retract that brake piston? Well, we do. We want to service it. We want to get the piston away to take the pressure off. So Chase can go ahead and remove the caliper assembly. So if I hit yes and you listen, what it's doing now, it's winding that piston back. And I'll show you that a little bit later when we close how it actually actuates. But that's pretty cool. It moved it back.
Well, now at this point, it's just as simple as removing a caliper. All you do is you remove the two caliper bolts, but you unplug the module first to be safe. So unplug the module, remove the two caliper bolts. Once you remove the two caliper bolts, you can go ahead and swing the caliper off like you normally would. And then you can take the bracket off the spindle assembly and you have it all ready to go to the bench.
Now, after we're done with the bench and you get it all back together, you just reverse the procedure, put it on, file your torque specifications. But then you come back into the vehicle before you move. And it says, "Parking brake retractor reset." We're ready to retract it now. So what we want to do is hit the brake and then go ahead and hit the parking brake switch. When we hit the parking brake switch, it's moving that piston back in contact with that actual rotor assembly and getting everything set up so we are ready to go.
Now, once we're ready to go, we can go ahead and run the car just like you normally would. It's similar to a brake job, but a lot of precautions to do it. But let's take a look at it on the bench so you can see actually what's going on.
Speaker 3: Well, we have the electronic parking brake assembly over here at the bench, and there's a couple of things I want to show you. But before we do, I just want to tell you, we cut one away so you can see how it actually operates, which is really, really cool. But we're missing a bolt here, number one. Number two, we have it hooked up to a power source so I can show you running in and out. You never want to do that. Why? Well, the car is full of sensitive electronics and computers that actually run this. It wouldn't put a direct 12-volt to it and run it in and out. We're just going to do it for demonstration purposes.
Now, the first thing. Once you get it over to the bench, you want to remove the motor from the caliper assembly, and that's pretty simple. You can see here there's an Allen key bolt here. What I'm going to do is just put it in, take it out, and it's really just that easy. Once I take that bolt out, then we can go ahead and separate the motor from the caliper assembly, which is really easy. But a couple of key points here I want to point out. First of all, there's an O-ring. Now this O-ring is a critical part of this. Make sure it's in there. It's stopping any debris... Any stuff that is going on getting into this motor assembly and doing damage.
Second, you actually have the splines. Now these come in six or 12 splines, so you want to make sure that your splines are matching up, from your motor to your caliper assembly. This one happens to be 12 and you can see it matches up right there with the 12.
Now, to reassemble it, just as easy. But also a couple of tricks I want to show you. The O-ring I'm going to hold down. But when I put this in there, it may not spline up together. It may be in an off position. What I don't want to do is torque down on that bolt and break that ear off. So, what I'm going to do, is I'm going to put it down on there, and you can feel it. But what happened, it's not really in the bolt hole. So we just clock it or move it over a hair to get to the bolt hole. But I know that I'm in the splines. It's okay to move the motor at that point to the left or to the right to get it in the splines. Now for my bolt, just simply come back. Reinstall it. I'll go get the torque specifications and torque it down. Make sure it's all proper. You're dealing with plastic and sometimes aluminum, so just make sure you don't over-tighten this. And like I said, make sure it's lined up in order to not snap off one of those ears.
Once I got that snugged up, I want to show you a really cool... how this thing works. Now you remember we retracted it. We went into the retract position and then we come out and we held. We can show you how to do that. And it's really, really cool. So if I come down here, I'm just going to put a power supply to it. And watch that piston as I do. Now I'm running that out. So if you put your emergency brake on right now, that little screw and ball ramp there is pushing that piston out and it's contacting and squeezing the rotor. That what's going on right there. Now this would be in the engaged position; I would have the e-brake applied.
Now, when we went into that service mode, what happened? Well, check it out. When we go into that service mode, it's going to reverse and it's going to pull that in. Why do we want to do that? Very, very critical. If I went right now with a C-clamp, which we never want to do, because a C-clamp a lot of times is going to push on this plug. When it pushes on the plug, it's going to snap it. You're going to do damage to the motor. So, just get rid of the C-clamp.
We can go back to an old caliper pusher, but we can't use it right now because we're not in the service mode. And if we're not in the service mode, what's going to happen is I'm going to push this back and mess up all those threads inside of there and our caliper is done. It's finished. So what we want to do... and what we did. When we went into the service mode, what the computer actually did is he ran it back. Well, you don't see the caliper moving or the piston moving back. That's because there's no hydraulic pressure behind it. It just moved it back. But, it made it safe to go ahead and use your caliper tool. You can come in here like this now and I can just do it like a normal caliper and bring it right back in there and go ahead and put it back on the vehicle, no problem.
Now when you're putting it on the vehicle, just reverse the procedure. Follow the torque specifications and make sure everything is secure with a test drive, just like we did. Go through the... reverse the process for applying it, get it out of the service mode so you can drive the car. Now, with electronic parking brakes, you should be real capable with it, but the key is follow the service manual. Every manufacturer specification is a little bit different. Follow it to a T and you'll do the job right every time.