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Parking Brake Unavailable

6316 Views 16 Replies 5 Participants Last post by  jena_k
Hey ladies and gents, I'm looking for some info on how to reset the computer on my 2020 Rav 4. I replaced the rear pads and rotors on the vehicle and it was my first time working with an electronic parking brake; I disabled the electronic parking brake to remove the old pads and rotors and upon attempting to reinstall the new ones noticed that the piston does not push back as I'm used to, and a clamp could not be used to compress the piston due to the electronic motor on the caliper. I looked it up and the vehicle had to be in brake maintenance mode so I attempted to do so - 3 pulls up, 3 presses and hold down on the parking brake switch. The caliper then decided to apply the parking brake and at the time the pads were not installed so there was nothing for the piston to push on therefore the piston was pushed out of the caliper. Finding no solution online I removed the electric motor by taking out the two hex screws, used a T-45 to wind the caliper back and then manually pushed the piston all the way back. I then reinstalled the electric motor and brakes and bled the system.

The brakes work great, no issues whatsoever but I cannot get the "parking brake unavailable - visit dealer" message to reset, I've tried a maintenance reset on the dash, I've also tried unplugging the battery for 5mins and I've tried going for a drive to see if it picks up that its been wound back. I'm wondering whether or not the electric motor is now mismatched on its position with the caliper (I doubt its that complicated, I would assume the sensor picks up pressure in the line but you never know) or if its as simple as a system reset on a scan tool.

I'm hesitant to bring it to a dealership because I doubt they would let me speak to a tech to explain the situation and will most likely try to install new calipers instead and I hear they are nowhere near cheap.

Hopefully there are some suggestions. Thanks.
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How long has it been since this happened? I had that message on my R4P but it was due (I think) to the mechanism being frozen up since I had parked it in/near a snow drift. It eventually cleared itself after a few days.

You can hear the mechanism work when you pull or push the brake lever. You may need someone to do that while you're standing next to the back wheels but it is easy to hear if it's moving or not.
 

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Why were you replacing pads and rotors on a 2020 RAV4? Were they worn out? If so, you must drive an awful lot of miles!
On many cars, the rear caliper pistons must be rotated to pull them in. The old c-clamp trick doesn’t work.
 

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I looked it up and the vehicle had to be in brake maintenance mode so I attempted to do so - 3 pulls up, 3 presses and hold down on the parking brake switch. The caliper then decided to apply the parking brake
Sounds like you did not do the Maintenance Mode procedure correctly-- the EPB canisters should have retracted the actuation rods NOT extended them. Here is the best video on how to do it. As the Toyota master diagnostic tech says, it's finicky and you should practice it before working on the brakes. The brake light on the instrument cluster must be flashing if you have done it correctly.
 

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I'm wondering whether or not the electric motor is now mismatched on its position with the caliper (I doubt its that complicated, I would assume the sensor picks up pressure in the line but you never know) or if its as simple as a system reset on a scan tool.
solution online I removed the electric motor by taking out the two hex screws, used a T-45 to wind the caliper back
Have you scanned for DTC codes? It probably needs a Techstream brake code clearing. Most likely it set a brake failure code when the piston came out of the caliper and you pushed it back in. Also when you manually retracted the EPB rod with the T45 this could have registered as an EPB malfunction and set a code. Even though brakes work OK now those codes are still in history so you get the warning message. I think your EPB canisters are probably OK since you say the brakes work fine now except for the warning message. It's always possible though you internally damaged it by manually retracting the rod with the T-45. I would do two things: 1. If you don't have Techstream capability (most normal, cheap OBD2 scanners won't read brake codes) try disconnecting the battery-both positive AND negative cables overnight and see if the message clears. 2. If not go to the dealer and pay for them to scan for codes and delete them and do any other appropriate computer reset. This won't be covered by warranty since you are responsible for the malfunction.
 

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Discussion Starter · #6 ·
Thanks for the replies, yes there are over 60k miles on the vehicle. The slider stuck on the LH rear which caused the brakes to prematurely wear. And yes it was not properly put into maintenance mode but once the piston was over extended it tripped some sort of code and did not allow further operation of the EPB, it now displays "Parking brake unavailable". I'm wondering if the system will not reset due to the code being in the system? And also if the motor "remembers" the position that it was last in.
 

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Discussion Starter · #7 ·
Have you scanned for DTC codes? It probably needs a Techstream brake code clearing. Most likely it set a brake failure code when the piston came out of the caliper and you pushed it back in. Also when you manually retracted the EPB rod with the T45 this could have registered as an EPB malfunction and set a code. Even though brakes work OK now those codes are still in history so you get the warning message. I think your EPB canisters are probably OK since you say the brakes work fine now except for the warning message. It's always possible though you internally damaged it by manually retracting the rod with the T-45. I would do two things: 1. If you don't have Techstream capability (most normal, cheap OBD2 scanners won't read brake codes) try disconnecting the battery-both positive AND negative cables overnight and see if the message clears. 2. If not go to the dealer and pay for them to scan for codes and delete them and do any other appropriate computer reset. This won't be covered by warranty since you are responsible for the malfunction.
Love the quote system on this site.. Thanks for the reply and yes this is the info I was looking for and I'm thinking along the same lines but I didn't know what the specific scanner I would need would be called. I don't believe I damaged the EPB with the t45 (it was easy to turn with my fingertips) but you never know. Ill give the overnight reset a try once this blizzard goes away and ill let you guys know how it goes.
 

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once the piston was over extended it tripped some sort of code and did not allow further operation of the EPB, it now displays "Parking brake unavailable".
OK-I did not understand from your earlier post that the EPB was now totally inoperative as well as getting the warning message. You obviously damaged the EPB canister when you used the T-45 to manually screw back the rod to retract it.I think you are going to have to bite the bullet and go to the dealer and pay for them to fix your mistakes. You may need a new EPB canister and a computer code delete and reset.
 

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Discussion Starter · #9 ·
OK-I did not understand from your earlier post that the EPB was now totally inoperative as well as getting the warning message. You obviously damaged the EPB canister when you used the T-45 to manually screw back the rod to retract it.I think you are going to have to bite the bullet and go to the dealer and pay for them to fix your mistakes. You may need a new EPB canister and a computer code delete and reset.
Now that I re read my post it sounds like I am saying that it was not displaying the EPB error until after I messed with the canister, but the "parking brake unavailable" message started to display after I attempted to enter service mode and the piston was over extended - so i believe the code is what is stopping the EPB from operating because even before I touched the canister it was displaying the error and not operating; sorry about the confusion.
 

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There are a number of conditions that cause you to get a "Parking Brake Unavailable" notification. It can be as simple as a bum battery or much more complicated like a defective Skid Control Module. Apparently all these things will post a "C" code. This is a DTC that starts with a "C". I believe only Techstream shows them. Here are some examples. Communication Device Font Rectangle Material property Screenshot
Font Material property Parallel Paper Rectangle
 

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Now that I re read my post it sounds like I am saying that it was not displaying the EPB error until after I messed with the canister, but the "parking brake unavailable" message started to display after I attempted to enter service mode and the piston was over extended - so i believe the code is what is stopping the EPB from operating because even before I touched the canister it was displaying the error and not operating; sorry about the confusion.
Here is a list of "c" codes relating to the brakes and EPB. I don't know if it is complete. If the overnight battery disconnect does not work, then also try putting the EPB into manual operation mode and repeatedly cycling the brake button on and off /up and down multiple times. Also try cycling multiple times in and out from automatic operation to manual operation. If these don't work you have to go to dealer.
 

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Here are some posts from the ToyotaNation 8th generation Camry forum (same EPB as our RAV4) about the canister or "EPB Actuator" which is the part with the rod that extends and retracts to operate the parking brakes. That is one very expensive SOB! $800 or more for one! Dealer repair over $2k! They apparently can get electrical shorts. This is why you should not manually retract the rod with a Torx wrench or mess around with them.
 

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Discussion Starter · #13 ·
Here are some posts from the ToyotaNation 8th generation Camry forum (same EPB as our RAV4) about the canister or "EPB Actuator" which is the part with the rod that extends and retracts to operate the parking brakes. That is one very expensive SOB! $800 or more for one! Dealer repair over $2k! They apparently can get electrical shorts. This is why you should not manually retract the rod with a Torx wrench or mess around with them.
Ouch well if that happens i think ill save the 2k and live without the parking brake 😅

Maybe ill make up a set of wheel chocks to throw in the back 🤣
 

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Ouch well if that happens i think ill save the 2k and live without the parking brake 😅

Maybe ill make up a set of wheel chocks to throw in the back 🤣
Eventually NAPA, O'reillys and the aftermarket are going to have to sell them cheaper--there are literally millions of RAVs and Camrys and probably other models with the same part.
 

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Just an update on the situation; I tried the overnight battery disconnection and there was no change. I took the vehicle to the dealer late last week (it also showed cruise control malfunction - i believe its because both systems are controlled by the skid control module) and they did a tech stream DTC reset, which didn't solve the issue. The tech said he then "reinitialized" the EPB canister and this rectified the problem. So far so good.

TL;DR - Don't attempt to enter brake maintenance mode unless your brake assembly is completely assembled; but if you do, an EPB reinitialization will bring the system back to default.

The code tripped was something along the lines of "EPB canister out of operating range". I don't have the techs notes with me ATM.
 

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Just an update on the situation; I tried the overnight battery disconnection and there was no change. I took the vehicle to the dealer late last week (it also showed cruise control malfunction - i believe its because both systems are controlled by the skid control module) and they did a tech stream DTC reset, which didn't solve the issue. The tech said he then "reinitialized" the EPB canister and this rectified the problem. So far so good.

TL;DR - Don't attempt to enter brake maintenance mode unless your brake assembly is completely assembled; but if you do, an EPB reinitialization will bring the system back to default.

The code tripped was something along the lines of "EPB canister out of operating range". I don't have the techs notes with me ATM.
Could you please post the dealer service order showing the tech's comments when you get a chance?
 

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Hey ladies and gents, I'm looking for some info on how to reset the computer on my 2020 Rav 4. I replaced the rear pads and rotors on the vehicle and it was my first time working with an electronic parking brake; I disabled the electronic parking brake to remove the old pads and rotors and upon attempting to reinstall the new ones noticed that the piston does not push back as I'm used to, and a clamp could not be used to compress the piston due to the electronic motor on the caliper. I looked it up and the vehicle had to be in brake maintenance mode so I attempted to do so - 3 pulls up, 3 presses and hold down on the parking brake switch. The caliper then decided to apply the parking brake and at the time the pads were not installed so there was nothing for the piston to push on therefore the piston was pushed out of the caliper. Finding no solution online I removed the electric motor by taking out the two hex screws, used a T-45 to wind the caliper back and then manually pushed the piston all the way back. I then reinstalled the electric motor and brakes and bled the system.

The brakes work great, no issues whatsoever but I cannot get the "parking brake unavailable - visit dealer" message to reset, I've tried a maintenance reset on the dash, I've also tried unplugging the battery for 5mins and I've tried going for a drive to see if it picks up that its been wound back. I'm wondering whether or not the electric motor is now mismatched on its position with the caliper (I doubt its that complicated, I would assume the sensor picks up pressure in the line but you never know) or if its as simple as a system reset on a scan tool.

I'm hesitant to bring it to a dealership because I doubt they would let me speak to a tech to explain the situation and will most likely try to install new calipers instead and I hear they are nowhere near cheap.

Hopefully there are some suggestions. Thanks.
I am currently dealing with the same problem, put the car into service mode with the caliper disassembled, causing the piston to completely extend. Had no choice but to remove the parking brake motor and manually winding the rod and pushing the piston back in.

Again, car drives fine but no EPB. Taking it in to the dealer later this week.

Any word on what you ended up having to do in order to have the EPB fixed?
 
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