I did search some of this stuff prior to posting, but nothing matched my scenario exactly I have three separate noises; 1. Sometimes (not all the time) there is an extended warning chime on startup (5-10 seconds) 2. Regularly, I hear what is almost an intermittent "chirp" when my foot is on the brake. It seems random. 3. I hear a pump or actuator moving intermittently during driving and once I shut off the car, it will do this for 10-15 minutes after shut down. From what I have read, it sounds like there could all be related to the braking system. I have no lights on, and Techstream does not show anything reported on the ABS computer. Are these just normal Prius noises?
1) are the doors closed (including hatch) tranny in park? 2) that's your failing brake actuator, no worries 3) a/c maybe?
What's the car? Your profile says 2001 (Gen 1), but you're posting in the Gen 2 (2004–2009) forum. Gen 1 and Gen 2 have different possibilities for what those noises could be.
I get a chirp from the brakes when towing occasionally. Was told by “senior” members here it’s the brake servo pushing more pressure into the system. Only happens on the first couple of brake activations
Asking us to identify noises with no symptoms, no warning lights, no date of manufacture of vehicle or how many miles or maintenance history is about as easy to accurately answer as answering when covid is finally going to be over.
It's a 2006. And it turns out there are C1241 and C1256 codes which have yet to trigger any lights. Would low battery voltage cause the accumulator to go haywire?
Maybe not haywire, but could maybe cause it to say C1241, meaning "checked your supply voltage lately?" That would be a case of a non-haywire brake controller behaving exactly as designed. Low battery voltage won't directly give you C1256; that code indicates low pressure in the accumulator, not recovering within the expected time. That can happen, though, if there's inadequate power getting to the pump. So if you've got any reason for doubts about your 12V voltage, this is a good time to follow those up.
Ok, the 12V battery checks out. 12.8V with the car OFF. Also it looks brand new. I have no dash lights at this time. I called a local shop that only works on hybrids and they said it could be a while before the lights come on. They confirmed the noises are likely the pump. $1250 for a used module, installed, $2400 for new from Toyota. Still does not explain the C1241. Toyota has some superceded part numbers with regards to the module. Were there improvements to the device? If so, does anyone know the most recent part number? If Toyota improved the part, then used might make sense but only if it is the correct PN.
C1241 is about the supply voltage arriving at the brake components, so if you check the battery voltage and like it, that just means looking elsewhere on that power path to find the reason for the C1241. Getting the INF code for the C1241 can also help there.
