5 seconds Buzzing Noise every time I depress brakes

You folks dont have that 1 day shipping up there yet???

 

Well, ok ... the thing is, here on PriusChat, there is another very mundane, or maybe quotidian is the better word, thing that happens day in and day out, which is that another person will show up and post a question that has this basic structure:

• Hey, I've got this thing happening
• Of course I know there are too many possibilities to tell me what the problem is without the trouble codes, nobody needs to remind me
• I don't have the trouble codes
• What do you think the problem is?

which leaves the rest of us with not very much to say, other than:

• ...

 

i'm usually willing to take a wag without codes, but they lead to a lot of wild goose chases

 

The key to whether a particular service campaign applies is whether the failure experienced is in fact the result of the particular defect identified for the campaign. Hence the importance of the diagnostic information; an assembly as complex as an actuator can fail in any number of ways, not all of which will be connected to whatever component defect was identified for a campaign.

A recall, of course, is different; if there's a recall for a component in your car, you get a new one unconditionally, whether or not it has even failed yet.

I have on good authority that the important bits in the brake actuator were supposed to have been made of the settler's ellum, but the last of its timber had already been used up.

 

Not that I know of.

By the same token, there are a few different sorts of recalibration/relearning steps that may or may not be needed after certain kinds of work or events. If the brake ECU wants to do any of those, its trouble codes will tell you which one(s) it wants.

 

It is possible for loss of nitrogen from the accumulator to lead to short and frequent pump runs, just as the loss of air from a well pump system's pressure tank has that same effect.

It is also possible for, say, one of the SLR valves inside the actuator to stop sealing completely, so that the pressurized fluid has a slow leaky path back to the reservoir. As the pressure bleeds off through that path, the pump runs to make it back up. Note that this is another independent way to cause the same symptoms, completely unrelated to whether the accumulator bellows might leak any nitrogen.

And it's not like there are just a few valves inside the actuator ... in a Gen 3, there are 14 electrically-controlled valves, not counting also purely mechanical valvish things like ball checks, or the relief valve in the accumulator.

You seem to be on a quest to find "the one" failure cause that will be the explanation for everybody who has the dash warning lights, pump buzz, and hasn't read their trouble codes yet, and for it to turn out to be one obvious thing that the idiot engineers forgot to think about. I don't know that reality will cooperate with you though.

 

I hear that some dealers sometimes 'forget' to report the exact codes and subcodes to you, unless reminded.

 

Wanting to keep you hooked I assume. Personally, if the hook popped out of my mouth I'd probably grab it and put it back in; they're likely the best option for finishing the job. Maybe...

 

Well, sure, Remember the actuator has a lot of parts, none of them separately available for replacement. Any of the solenoid-valve-related codes, for example, C1211,1212,1214,1225,1226,1227,1228 and their many subcodes, unless you lucked out and found they were caused by an electrical supply issue, would have to be repaired by replacing the actuator. The owner who comes back from the shop with a replaced actuator on the bill is going to say that was an actuator failure, right? Same for any of the pressure sensor codes C1246,1256,1352,1353,1356,1357,1364,1368, and so on.

If you had a C1214 showing a failure to sense the target pressure in one of the brake lines, you would first check for a leak in that line or a wobbly disc that would be an easy physical explanation for the pressure being wrong. But if that didn't pan out, the cause would be either the valves in the actuator, or the sensors in the actuator, or the ECU (also in the actuator, in Gen 3), so the repair would be to replace the actuator, and would be (rightly) regarded, by the owner paying the bill, as a failure of the actuator.

For that matter, since all of the codes are detected by the ECU, and the ECU is a not-sold-separately part of the actuator, it is possible for any brake code at all that the steps of troubleshooting to find the cause may lead to replacement of the actuator, and the customer paying the bill will (rightly) consider that as an actuator failure.

It just wouldn't be right to lump it together with whatever failure cause is at the bottom of the ZJB campaign.

 

That is a nice clip for a generic understanding of how ABS works in a generic car, though for understanding a Prius brake system, the explanations in the New Car Features manual or in the technician training courses on TIS would get a lot more of the details right.

 

those are japanese asterisks, click on them for sub codes