Brake problem approach

The 03 Prius we gave to our house keeper two years ago has the brake problem. My wife and I visited her Thursday evening and it has all these gross symptoms. She reported a friend tried to "bleed the brakes" but to no effect. I plan to return Saturday or Sunday and do the following:

1. 12V power-on reset to clear the codes and replicate the problem.
2. Bring laptop with old TechStream and hopefully find the OBD connector I left with the car. Reading the codes will be trivial.
3. Bring an OBD pig-tail with Ts and CG identified. This should make it easy to read the flash codes if we can't find the OBD-to-USB adapter.
4. Use Vol 1 of the diagnostics manual to identify the likely failed part(s). I can not rule out the brake fluid having gotten too low from pad wear so I'll check them.

I'll pickup a Harbor Freight, manual vacuum pump bleeding kit, $25:
Brake Bleeder and Vacuum Pump Kit

Even if we have to replace failed parts, we'll still need to bleed the brakes. Since I'll be checking the brake pads and shoes, reaching the individual bleed nipples should be easy enough. I'll bring a small, floor jack and jack stands.

Comments @ChapmanF , @ericbecky , @3prongpaul or others?

Bob Wilson

 

Although I have a portable air pump, it is small and I'm not sure it is up to this task. I've got it in a storage shed and will bring it back to the house for another task.

Bob Wilson

 

No luck on bleeding the brakes. Worse, my Ts to CG jumper didn't flash the ABS codes but I had the door open. If there is a 'chicken dance', please share.

I've ordered a replacement TechStream and OBD cable.

Bob Wilson

 

So I ran the new TechStream and this is what it reported for 'health'. Note there are no codes for the ABS:


TechStream reports the engine and hybrid codes.


All attempts to get the ABS codes failed with a popup showing a instruction failure. Fortunately, I had an OBS jumper setup to trigger the car to read out the codes:

• 51 - Brake booster pump failure
• 52 - Motor ON time abnormal
• 56 - Accumulator low pressure
• 59 - Malfunction regeneration of HV ECU
• 64 - Hydraulic failure

Bob Wilson

 

Yes.

There is a high-pitched squeal that does not sound like an alarm.

Bob Wilson

 

Was the a Toyota TIS about the brake assembly with any sort of extended warranty?

Regardless, I need to use a 12V battery to test the motor but I'm pretty sure it is fubar. Reviewing the procedure. Now to find parts:

• $99 - eBay
• $345 - eBay with 3 mo warranty
• $299 - Amazon used
• $199 - new accumulator if motor works

Bob Wilson

 

There are at least 9, NHW11 Prius in Nashville and they quoted $25 for the part over the phone. I'll bring bring the owner, my wife, her dogs, tools and drive up on Saturday / Sunday. Pulling the part will be practice for pulling the part from her car.

Bob Wilson

 

I got the cowling cover, windshield wiper assembly, cowling cover off in 39F (4C) in a light drizzle. But dark arrived and my cell phone flashlight appears to have 'problems.' Worse, the brake booster is way down so measuring and testing the booster motor will have to wait another day.

We'll move the car into her garage later and setup a proper shop. Out of the wind, wet, and cold, the rest will be fairly easy. Once I confirm the motor is fubar, a trip to Nashville the next 'nice' day.

Speculation, I wonder if raising the car and dropping the booster pump may be the way to go? That avoids the heater core and A/C pipes.

Bob Wilson

 

Found it: abs brake light buzzer going off C1356 | PriusChat

• jack up the passenger side
• pull the passenger side tire
• noddle it out

This sounds like the best way to access the connectors for the brake test. I'll try it once the car is in her garage.

Bob Wilson

 

With the cowling cover and windshield washer removed, this is what you see. Obviously there are coolant hoses and A/C hoses in the way:


So I took the suggestion and looked at taking it out from the wheel well. First a flimsy splash shield to remove:


Three 10 mm, sheet metal type screws and it folded away:


Looking up, I can the the back of the pump motor but there is plate held by two pairs of 10 mm bolts. Two I racheted loose but I forgot to bring my metric box wrenches:


I went to the top and discovered the two connectors:


Great, turning on the ignition I should see the B+ which measured 10.5V OMG!

The motor pins are in a blind area so I'll have to figure out two custom jumpers to ohm it out. If within range, I'll have to apply 12V to see if the motor runs ... I wonder from where?

I've got to get the 12V battery back to normal voltages and retest the car. If a low battery caused this brew-haha, I'm going to kick my own nice person. I'll retighten the two loose bolts on the flat plate, put the car together, and get a replacement battery.

Bob Wilson