2005 brake failure

2005 brake failure:

I would appreciate responses be limited to technical only. I am trying to solve this problem and do not require any emotional support in the way of opinions or other. I'm submitting this new thread because I haven't found anything quite like it after researching the site.

History - Purchased "Certified" used with 60,000 miles from Toyota dealer. Now at 110,000+. Dealer performed recall work on inverter coolant pump and reprogrammed computer during same visit about a year ago. Brakes appear to be original at approx. 50% worn.

My failure was preceded for a week or two by subtle changes in the feel of the brakes, most notably what I would describe as inappropriate "twitching" of the vehicle as I was creeping in either direction - in other words - a constant pressure on the brake pedal did not result in a smooth motion of the car (under 7 MPH).

Today 4 warning lights went on related to this problem and this is the first time that has happened. From left to right - (1) "Brake" light (same one that comes on when parking brake is set, (2) yellow brake warning light symbol with exclamation point in middle, (3) ABS warning, (4) VSC light. No audible warnings. I have an appointment with a local small service shop to have them scan to determine what codes have been set.

The only thing I have done to the brakes up to now is adjusting the rear brakes because they were grabby but that was months ago.

Now that the failure lights have lit, the vehicle is very hard to brake smoothly. At first it takes extra pressure to initiate good braking and then with a little more pressure the effectiveness feels more normal and it jerks between the two modes worse at lower speeds.

I'm wondering if air could have entered the system through a leaky master cylinder rear seal or anywhere else. I haven't found any leakage anywhere including in the interior firewall area. Reservoir is solidly between the low and high marks and I've never added any brake fluid.

This is a good site, I look forward to hearing from the knowledgeable ones!

 

I am getting regen on coasting but not on brake application. The accumulator is loud and clear but it operates now when I open the driver's door and power is off, I don't recall that happening before??? Rear brake adjustment was just the adjuster, never opened a bleeder on this vehicle anywhere. Brake effectiveness is OK on hard demand (as in can rely on brakes being there) but loafing around as in city driving the response feels like they are not coming on until suddenly they do which causes very uncomfortable passenger conditions, as in very jerky stopping below 20 - 15MPH. When I get codes I will report them. Thank you very much!

 

Tried the battery disconnect/reset. No change. Don't suspect moisture due to garaged daily but I wouldn't rule out connection or bad wire as I am amazed how thin the wires are in these vehicles and can probably wear through very easily. Thank you!

 

Problem resolved, (thanks for the hug Tom even though I said I wasn't asking for any emotional support).

According to the dealer, Lum's Auto in Warrenton, Oregon, the stored code was C1247, reporting a bad stroke sensor on the brake pedal. Cost to replace, $185.72 for the sensor, $190.00 for labor which included 2 visits, one to diagnose, one to perform the repair.

So, in conclusion, I went in assuming I was going to have to trade the car in due to high cost for repairs, but was pleasantly surprised. On the first visit they cleared codes after diagnosis and
I was able to drive the car for a few days with no symptoms until the part arrived for replacement.