Brake ABS and (!) light on. Actuator or something else?

Hello,

Just as many others have posted, I have the BRAKE, ABS, and (!) lights illuminated on my dash. After some searching online (mainly here), it seems that the 2nd gen is known for issues with the brake actuator (to bad it's not 2017 still ). Before I potentially fork over a lot of money (or time as I'd like prefer to attempt a DIY), I wanted to rule out other possible problems.

Here's some additional info:

• I stopped by O'Reilly's and had them read the car codes. It came up with C1344 - Malfunction in the hydraulic system rear left. This is inline with the flashing codes I got: 65 (!) and 42 ABS. (as I found here: http://www.gwzz.com/tmp/Prius-RepairManual-2005.pdf)

• The 12v reads 12.4 using a multi-meter with the car off (not ideal, right?).

• I do not hear the actuator constantly running, just every once in a while for about 5 seconds. I did, however, loose / had extremely decreased braking power after having been parked for over an hour and when backing up. This lasted a few seconds before regaining brakes.

• I inspected the RL wheel and found the drum to have some scoring, it's not perfectly smooth. Additionally, I have about 1.5mm on one pad, and 2.5mm on the other. ​

So to restate my question, how can I determine that it's the actuator and not something else? Could it be something to do with the wheel such as the brakes, drum, some sensor or the bearings?

Thanks in advance for any help,

Joe

 

Another symptom, rear left brake drum was cool to the touch after driving indicating those brakes aren't working.

 

After looking through the manual, I went ahead and ordered a mini VCI with techstream. That should give me the INF codes I hope, and I'll need it anyway to bleed the brakes. Manual says it could be air in the system or junk in a solenoid (before moving on to the actuator).

 

I wanted to update this thread in case anyone else seems to have the same symptoms. I used techstream to confirm that I had a malfunction in the left-rear brake, and used techstream to bleed the brakes. My LR brake had a ton of air in it. I reset the codes and had no issues for 2 weeks. My prius has the MFD issue. I had a rain storm and the MFD failed and I rode around without it working for a few days. After resetting the MFD (battery plug), the lights were on again. I repeated the process and there was now a little bit of air in the LR brake. I haven't had any issues since. My guess is somewhere
there is a minor leak in the LR brake system.