Disconnect the 12 volt battery before replacing the front brake pads, I have heard YES and NO is there a mechanic on here that can really say for sure. thanks
Yes, you need to disconnect the 12V battery, and also press the brake pedal a few times to get rid of residual pressure in the brake actuator. Or else, don't be surprised if the piston shoots out of the brake caliper if the skid control ECU decides to power up the brake actuator pump while you have the caliper removed.
thanks Patrick, is the pressing of the brake pedal done after the battery has been disconnected? and I have also heard that after the new pads are installed I should pump the brake pedal a couple of times to seat the pads, is that correct. again thank you
Yes, the pump would just run to re-establish brake pressure if the 12v bus was still energized. JeffD
thanks Jeff, any info if you need to pump the brakes again after installing new pads before connecting the 12 volt back up
Yes. There is no point in pressing the brake pedal while the 12V battery remains connected. Pressing the brake pedal a few times after the 12V battery is disconnected achieves the purpose of relieving hydraulic pressure in the brake actuator pressure accumulator, and also discharging the emergency brake power supply (the large rectangular black plastic box full of electrolytic capacitors, mounted next to the 12V battery.) Yes, it would not hurt to do that prior to reconnecting the 12V battery. The point of that is to take up the slack between the caliper pistons and the new pads, before the skid control ECU is back online. That hopefully will prevent the ECU from logging a DTC when it is powered up. Do not allow air to enter the brake lines upstream from the wheel cylinders, as it will be really hard to get the air out without the Toyota diagnostic laptop or equivalent.
Thanks Patrick, I am only replacing pads as everything else looks good. being in AZ and very little moisture, so no rust to contend with even. So no need to remove the hoses just want to remove the old pads and install new. So I should not have any DTC or red triangles of death by disconnecting the battery and pusing the piston cups in , and then installing the new pads etc.. Is there a formal write up on here that I might have missed that shows the steps, ? or even a video. If I can get my daughters camera I will film it when I do this job I just want to make sure I have the steps right, I appreciate your help
Following the above procedure then treat the pad change as any other car will not give you any problems. You will have to set the drivers auto window, and you will loose the radio presets. Also do not shut the tailgate with the 12 volt battery disconnected, it will not open without power. To reset the window, power halfway down then power up all the way and hold the window switch up for a few seconds. John (Britprius)
If you don't leave the hatch open, then you have to lower the rear seat back, crawl into the hatch area, and find the mechanical release to the hatch lock. This is a small shiny metal lever which can be seen when you open a small rectangular door located at the rear of the black plastic tray over the spare tire.
one last thing, I was reading where toyota wants to use a lithium soap base glyco grease on the slide pins and on the shims. I have Permatex 24115 Ultra Disk Brake Caliper Lube Hi-Temp in my tool cabinet, will this also work on the prius brake slide pin or does it have to be what they say? thanks, if it has to be what they call out where to buy other than from toyota dealer? I also have permatex ant seize it is a copper color i have always used for spark plugs, would that be good for the slide pins?
PC member "Agape" has tried different greases and came to the conclusion you need the correct grease. The copper grease is fine for the back of the pads and shims. See link below by Agape, for Toyota part numbers and full caliper parts description. parking brake, rear pads John (Britprius)
I think the Permatex grease is excellent. Agape was informed to use the copper as it was thicker than the stock Toy grease to reduce rattling but nothing thicker than that Permatex gone2green has. Its like candlewax to prevent rattling. I have used that for years its the best on the market and I recommend it. Pins and back of shims. Don't use gas to clean parts. Not safe and hard on body to smell that all day. Front of car will smell like gas. Not good. Use the proper spray brake cleaner. Don't forget to flush out caliper slider holes and threaded holes with brake cleaner. There full of casting crap. Just stuff a rag in the piston hole to protect the boot. But the boot is pretty damn tough anyway. While there in and to finish clean the brake line hose off and apply BlackMagic Protectant to the hose rubber. Will extend its life and do the same to the CV boots inner & outer. This stuff: Pro-Shine Protectant | Black Magic Car Care Products
After doing more research on the permatex (green) it says it is good for rubber but when you read the outcomes , people state it gums up, dries out and does not play well with rubber. So I called 2 toyota dealers out here, one being riverview and the other earnhardt both really had no clue what the lithium soap based glycol grease was, as one tech said he uses disc brake grease p/n 08887-80609 and he said he also has used p/n 08887-01206 (rubber grease) and has used both greases for everything, so no conclusive answer there, so back to the internet where I find this " Lithium Soap Base Glycol Grease - The Garage Journal Board . They speak of this litium soap base grease. So then on my other phone call back to toyota the parts guy opened it and said it is thick, smells like pag oil and his techs generally use the disk brake grease as it cost more and what ever is left over they keep. So I am going to go pick up a tube of the toyota rubber grease to check it out it cost 10-13 bucks Permatex 85188 Ultra Disc Brake Caliper Lube, 0.5 oz. : Amazon.com : Automotive I just saw this stuff it has a different p/n than the stuff I have already might even try this stuff out.
Yeah thats the stuff I thought you were referring to. Its green and feels like candle wax. 100% synthetic. Really good stuff. Last time I used it on my Crown Vic and so far at 40,000 miles still running really good. No noise.
