Looking for a Skilled Local Gen 2 Prius Mechanic in Syracuse

i can't imagine how the car can start itself without a 12 volt

 

Yeah that's a pretty good one I have to see that so without without the car would ready you step on gas and engine fires rt up? I no think so .sounds like DC to DC converters intermittent or such . Seems like it's draining 12v or not charging till last minute . With a weak charge system already in place . Bad

 

Actually if I was correct that's a stupid easy fix I wouldn't dump my car for it unless it was in real poor condition I couldn't use it for a work vehicle or so on the AC don't work etc .

 

The first code implicates a poor 12+ supply to the brake ABS. The other code is saying there is a communications malfunction between the skid control ECU and the brake control power supply assembly.

The first code is saying that AVC-LAN communication is impossible. The second code is saying the CM has failed (again). The first code might be because of the second code, so fixing the CM would be the first job to tackle if it were me.

You need to be very wary about what you "read online". Unless you test the battery, you cannot say the battery is good, even if it was replaced three months ago. Even so, I'd be thinking that there might be a problem with 12 V reaching components rather than a problem with the battery.

Did you or your mechanic actually do any diagnostic testing that is relevant to the codes you found, or are they just loading the parts cannon and hoping for the best?

 

Well that's the last thing you usually want to do but great. The the first thing to do w comm issues . Is physically test said 12V it's AGM in this we looking 12.3 to .7 at rest. Fall much below that . Things get fun. You're seeing faded faint display . Maybe 12V hasn't much behind it.

 

With a dim display and everything cutting out first thing I'd be doing is load test 12V battery it has to pass period . Until that verified you read thru here it's about 20 to 15 posts we get to oh by the way the 12v fell flat on its face . Replaced like a new car . We're at about 15 or so now I imagine

 

all the best!

 

Maybe it wasn't actually off - it can be hard to tell if the display is out because of the capacitor issue. Also in that state the car often refuses to turn off. If the car is running, even "silently", the 12V can be removed and the inverter will keep 12V going. They then did something to make the gas motor start, or the display kicked in briefly, and miracle of miracles, car starts without 12V. My money is that if they had put a voltmeter across the battery leads while the battery was gone it would have shown around 13.9 volts. They didn't do that because, why would you (normally)?

 

I don't know if that is entirely true. Some warning lights can work when the CM has failed.

Probably because the B1271 means exactly that.

It may be a different capacitor this time, so maybe it might be worth doing the three main suspects.

This thread, Combination Meter Repair - DIY, pinned in the Gen 2 Prius Care, Maintenance, and Troubleshooting forum, has all the details.