Can't get the rear brake piston to compress! 2016 CX-5

[pbesong]

I need my car tomorrow and I'm trying to do a brake pad/rotor job on the rear. I got the old rotor and caliper replaced but when I went to compress the piston back into the caliper, I followed the instructions here: https://www.mazdas247.com/forum/sho...nce-Mode-for-2016-2017-CX-5-electronic-brakes to allow me to compress the piston. I'm using a C-clamp as I don't have that little tool. Was told it would work. But I can't seem to compress the piston at all with the C-clamp. I just doesn't want to go back into the caliper. When I activated the maintenance mode I heard the motor run and thought maybe that would make it retract into the caliper then i could just push it in, but it actually pushed the piston OUT and i can't seem to get is started back in. Here is a photo of the caliper with my C-clamp on it. What do I do to reseat the piston???

My EPB maintenance mode light is on and the switch is flashing yellow.

I also tried turning maintenance mode off in case I did something wrong so i could try again, but the instructions don't seem to work. It's still in maintenance mode and switch is still flashing. Also had some brake fluid squeeze out of the rubber around the piston. I had the brake fluid lid off before i set the maintenance mode. Did that hurt something? Thought it should be off if compressing the piston.

 

[pbesong]

Well that didn't go too well. I ended up finding a youtube video on manually resetting the electronic brake here: https://www.youtube.com/watch?v=wAB43eO7wIs and it allowed me to reseat the piston, however I could not get it down far enough to span the new brake pads. All I could do was to put the old rotor and brake pads back on till I can figure it out. At least I can drive it now. The procedure in the video is the same for the Mazda, instead of torx screws they use allen bolts and a hex-headed adjuster bolt. I wound the adjuster bolt all the way down till it stopped and compressed the piston as far as I could but it wouldn't budge after it got down to about 3/8" from where I needed it to go. Just could not fit the caliper over the new pads for anything

The brake maintenance mode light will not turn off either. I tried holding the switch down and foot on the gas while hitting the start button 3 times twice, but it won't turn it off. Tried resetting it into maintenance mode again, then trying to turn it off, but that didn't work either. I can drive the car, but the emergency brake light keeps flashing and it's still in maintenance mode. pissing me off. half hour job is turning into a nightmare. Any help gladly accepted!

I'm also going to get that compression tool as I don't think the C-clamp is probably a good idea being that I had to attach one end to the plastic housing of the EPB. Ended up making my own tool to use for tonight.

 

[blackcx5]

You have to press the start button twice first so car is in "ON" status. Then press on accelerator pedal and hold then pull up on the EPB switch and press start button 3 times.. This should end maintenance mode.

 

[blackcx5]

Why did the piston come out so far as seen in your picture?? The only way that is possible is if you removed the pads first and engaged the parking brake by accident..

From your description, it seems the C- clamp cannot be used ... Because like you said the rigid side is up against the plastic housing. And probably when you tried to compress the piston back.. The plastic housing flexed and. There was not enough force to compress the piston from the other end. I think if you had the right tool you could have compressed the piston.. I think you exacerbated the problem by accidentally engaging the e brake without any pads so the piston was pushed out to the max limit..

 

[pbesong]

i did not know that you had to still have the pads in before setting it to maintenance mode. I figured i'd wait till i was ready to compress the piston.

I thought i followed the directions, but maybe had the gas in before turning the car on. I'll give it another shot. I doubt i did anything by using the C-clamp. it would not move at all, so I didn't push it.

I did make a similar tool that worked to compress the piston once the electronic motor was off. It was a large thick washer that I used an angle grinder to straighten one side so it would fit into the caliper right. Worked, but would be better to get the real thing.

 

[pbesong]

I tried again to get it out of maintenance mode, but no dice. I'm afraid i'll probably have to take it to a mechanic. I can drive the car, but orange maintenance mode light is on and the light on my parking brake flashes as well as the red parking brake alert on the cluster.

 

[blackcx5]

i did not know that you had to still have the pads in before setting it to maintenance mode. I figured i'd wait till i was ready to compress the piston.

I thought i followed the directions, but maybe had the gas in before turning the car on. I'll give it another shot. I doubt i did anything by using the C-clamp. it would not move at all, so I didn't push it.

I did make a similar tool that worked to compress the piston once the electronic motor was off. It was a large thick washer that I used an angle grinder to straighten one side so it would fit into the caliper right. Worked, but would be better to get the real thing.

ah, that explains it... it's self-calibrating, there is a force sensor expecting to feel the brake pad, so when it didn't sense a pad the piston just kept going and going until it just couldn't go anymore..

hopefully dealer can just reset the e-brake system for you and get rid of the flashing dashlight.

 

[CX-5um]

The rears with electronic brake requires a tool with adapter...........to make things much much easier. I purchased my tool kit from amazon. You can buy one locally or borrow one from a local store like AutoZone.

I don't remember a maintenance mode? I just Twisted the pistons back.

 

[pbesong]

yeah i'm going to get that tool, but luckily i was able to make a reasonable facsimile of it using a large heavy-duty washer, a bolt, and a nut. By slicing off an edge of the washer in a straight line with my angle grinder I was able to make it fit pretty well in the caliper. maybe I'll take a pic for if someone needs to make one in a pinch.

 

[blackcx5]

yeah i'm going to get that tool, but luckily i was able to make a reasonable facsimile of it using a large heavy-duty washer, a bolt, and a nut. By slicing off an edge of the washer in a straight line with my angle grinder I was able to make it fit pretty well in the caliper. maybe I'll take a pic for if someone needs to make one in a pinch.

just make sure the piston notches are lined up with that peg on the back of rear brake pads... see my post #22 in this thread :

https://www.mazdas247.com/forum/showthread.php?123861563-Maintenance-Mode-for-2016-2017-CX-5-electronic-brakes&p=6596526#post6596526

 

[pbesong]

Is there a good way of lining the peg up? i thought i read somewhere just keep it north/sound.

 

[yrwei52]

Heres the official procedure to replace the rear disk pads for 2016 Mazda CX-5 with EPB posted by Anchorman a while ago:

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[yrwei52]

So by replacing the rear disk pads, the EPB motor power needs to be disconnected after its been put in the maintenance mode. And the rear caliper needs to be removed to take the pads out. Dont know why but its the perfect time to lub the caliper pins. Never rotate the caliper piston while pushing it into the caliper with those special brake tool or the caliper internal parts could be damaged! The only brake tool you might need is a traditional disk brake expander tool showing in the picture. A large C clamp should do the job too.

 

[pbesong]

thanks. So it says to disconnect the electronic cable after putting it into maintenance mode? I guess that would prevent resetting it by accident. hoping i can at least get the piston seated enough to put the new rotor and pads on tonight. perhaps the other side will go easier.

 

[pbesong]

I don't think a large C-clamp is such a good idea since the EPB housing is made of plastic.

 

[yrwei52]

Based on your picture and you mentioned the brake fluid was coming out from rubber seal, the piston definitely had been pushed out too far by EPB motor! I hope the piston seal didnt get damaged, so as the EPB components inside of the rear caliper. The good thing is you didnt really force the piston in with your C clamp while your EPB wad not on proper maintenance mode. It you cant get the EPB maintenance mode warning light off after you followed the proper procedure I posted, unfortunately you may have damaged something inside the caliper.

Has your 2016 CX-5 performed the EPB TSB which would replace your rear calipers with a revised version?

SkyActiv TSBs (Technical Service Bulletins)

TSB R052/16C - Noise from REAR BRAKE/Trace of Rear Brake Dragging

 

[yrwei52]

I don't think a large C-clamp is such a good idea since the EPB housing is made of plastic.

Yeah the type of disk brake expander tool showed in the document is a better one. BTW do you use OEM or aftermarket disk pads? And do you use new rotors or just resurface the old rotors?

 

[CX-5um]

This kit was successful for me. https://www.amazon.com/dp/ (commissions earned)

Came with 10 different adapters. 1 fit pretty good for me for the rear piston.


Illustration of the OEM tool
https://www.bing.com/images/search?view=detailV2&ccid=G3wsdMA4&id=86D409A36BCBFC2FB88103C2DB812A5E790F6119&thid=OIP.G3wsdMA4gGrv2J9B1qa8cwHaEZ&mediaurl=http%3a%2f%2fwww.mazda3tech.com%2fimages%2fbooks%2f890%2fam3uuw00001771.gif&exph=253&expw=426&q=49+F043+002&simid=607993391196735800&selectedIndex=0&ajaxhist=0


Essentially you need to use a smooth disk with 2 notches sticking out. The disk will not harm the rubber seal cover and the 2 notches grab the piston to be turned.

 

[yrwei52]

This kit was successful for me. https://www.amazon.com/dp/ (commissions earned)

Came with 10 different adapters. 1 fit pretty good for me for the rear piston.


Illustration of the OEM tool
https://www.bing.com/images/search?view=detailV2&ccid=G3wsdMA4&id=86D409A36BCBFC2FB88103C2DB812A5E790F6119&thid=OIP.G3wsdMA4gGrv2J9B1qa8cwHaEZ&mediaurl=http%3a%2f%2fwww.mazda3tech.com%2fimages%2fbooks%2f890%2fam3uuw00001771.gif&exph=253&expw=426&q=49+F043+002&simid=607993391196735800&selectedIndex=0&ajaxhist=0


Essentially you need to use a smooth disk with 2 notches sticking out. The disk will not harm the rubber seal cover and the 2 notches grab the piston to be turned.

The fancy brake tool set with many adapters you linked is mainly for the rear disk brakes also used by mechanical parking brake. The adapter needs to fit the size of the caliper piston, and 2 dots on adapter are to fit 2 holes on piston to turn it while pushing the piston into the caliper. You can also rent this brake tool set for free from AutoZone even if you dont get pads from them.

But for rear disk brakes with EPB on 2016 CX-5, you dont turn the piston while pushing it into the caliper, or the internal components may get damaged.

Read the warning in official Mazda document I posted earlier.

 

[Unobtanium]

...and people talked trash about me paying the dealer $150 to do my brakes...

Seriously, you're doing it old-school, man. I did what you are doing a decade and a half ago, and it worked fine on the cars then. These new cars? They are annoying in that all of them work different, and are a PITA to learn about, especially if you break something $$ in the learning. I can empathize with OP, this is how my brake job on my Infiniti went. Since then...dealer.