2017 XC90 Rear Brake Caliper

pkonigsberg · Post by **pkonigsberg** » 09 Dec 2019, 13:50

Hello. I have a 2017 XC90 and with only 18,500 miles have run through the rear brake pads and am into the rotor in the rear brakes. Fronts seem ok for now. I think a stuck piston is pushing on the rear pads and that is why they wore out so fast. I bought a set of pads and while I got the caliper off on the rear, the piston wouldn't budge at all. I used a C clamp and I opened the bleeder valve and fluid dripped out but got very little movement. This seems like a common problem in this forum.

I took it back to the dealership (I should be under warranty for a stuck piston) and they said the piston is not stuck but you can't push it back with a c clamp because there is special computer software that is needed to release it. I wanted to ask this forum if anyone knew anything about this special software needed? Most posts seem to be for XC90's that are older than 2017 so maybe things have changed. I would be really disappointed if I bought a car that I can't change brake pads on and will continue to burn through them every 18k miles. Thank you for any advice.

Masscomguru · Post by **Masscomguru** » 09 Dec 2019, 18:49

Yup, starting with the p3 models, the electronic parking brake needs to be fully released. A service computer is the only way I know of to do this.

pkonigsberg · Post by **pkonigsberg** » 09 Dec 2019, 18:58

What is a p3 model?

Masscomguru · Post by **Masscomguru** » 09 Dec 2019, 19:54

Re-designs starting in 2011 across the model line.

pkonigsberg · Post by **pkonigsberg** » 09 Dec 2019, 20:55

Does anyone here know of a way to get this rear brake released on a newer XC90?

pkonigsberg · Post by **pkonigsberg** » 09 Dec 2019, 20:56

Sorry I meant to say anyone else?

wanderdüne · Post by **wanderdüne** » 10 Dec 2019, 06:19

I have not tried this personally, because my XC's are older; but this scanner is purported to be capable of releasing the electronic brake. I have one of these and it's a very good scanner for Volvo/Saab. It's pretty capable.
https://www.amazon.com/iCarsoft-systems ... 811&sr=8-1
Also, it does read the Volvo factory codes as well. *possibly contact the seller here; they sell several scanners and could verify or suggest another one.

* was curious about this and saw this blog from FCP. Maybe it would work? https://blog.fcpeuro.com/how-to-reset-a ... a-volvo-p3

Post by **jimmy57** » 10 Dec 2019, 11:51

All car makers have designations for the common design/common component platforms their models are built on. The 2007-> S80, 2008-> XC70, 2009->2016 XC60, 2011-2018 S60 are P3 platform. The original S80, XC90 S60, and second generation XC70 and V70 are P2. Your new XC90 is a P5 (they referred to it as SPA in some articles but it is a P5 in the usual designation scheme).
The parking brake release doesn't require software, it requires a capable scan tool with parking brake service access. The parking brake can also be released to service position manually. You remove the electric motor and then use a bit that that inserts into and will turn the screw jack that applies the piston to pads. The screw is a triple square 12 point head (different than double hex 12 point) but it can be turned with a torx 25 or 27 IIRC. you usually can turn by hand or use a nut driver handle. You will turn it 15 or so turns to get it released. It will bind when fully released. Check pad opening and then turn it few turns to see if you are driving pads closer. If you are then reverse direction. Turning it towards released will not back off the piston, it just backs off the screw jack so you can push the piston in. After pads are fitted and caliper is back in place then you can turn the screw jack to apply park brake. First pump brake pedal to push piston and pads against rotor. Then turn the screw jack to apply piston as noted by the screw getting hard to turn. last step is to back the screw off a couple of turns. The newer cars often will set a message and code if the screw jack is not applied as the system expects to see current go high when the park brake applies in no more than about a second. It backs the motor off for about 0.7 second in normal operation to release brake.

Post by **oragex** » 11 Dec 2019, 02:58

The above works on most cars with electric parking brakes. As mentioned, the idea is simply to remove the electric motor from the caliper. These are simple electric motors that rotate a screw-in piston that pushes on the parking brake pad. Once the motor is out, the piston can be turned the correct way to release the pressure from the parking brake pad.

pkonigsberg · Post by **pkonigsberg** » 11 Dec 2019, 09:28

I had the electric motor removed and put a 12 point socket on the back end of shaft that appears to go into the back of the piston. I got about half a turn counterclockwise on it and that was it. That didn't release the piston. It did not occur to me to try going clockwise. I ordered the Autel scanner and it should arrive tomorrow so I will let folks know if that works. (I would have tried the iCarsoft device but that was going to take longer to ship to me.)