Last night on the way home I had some strange behavior with the cruise control on my 2005 Prius. I had just pulled into the left lane to make a left lane exit on the highway, and the driver behind me had his Xenon high beams on. He wasn’t flashing me to get out of the way since I was pulling away from him; he was just mindlessly driving down the road blinding everyone in front of him. I tried to flash my emergency flashers to wake him up and when I did the cruise control cut out. Not only that, but the cruise control light started flashing, indicating a cruise failure. The rest of the way home on the interstate I could not get the cruise control to work. When I got off the interstate I shut the car off, restarted it, and the cruise control worked again. So, I decided to see if I could recreate the problem. I hit the emergency flashers with the cruise control on it, and the cruise control immediately canceled. This time and the several other times I tried it, I just hit resume and it would work again, with no flashing error lights. Has anyone else seen this behavior in their car?
I was initially sceptical, but according to the wiring diagrams the Hazard Warning Switch is fed into the Body ECU, so the car does indeed know when you put the hazard indicators on. It may be a safety measure. Never seen it mentioned or documented before.
Don't misunderstand me here. I'm not claiming this is a feature. I think it's more likely either a wiring fault in my car or a software bug. I was just curious to whether anyone else had experienced this.
I'd say it's definitely a bug; if it were a feature, then when your flashers were turned OFF, the cruise should be allowed to turn on again, n'est-ce-pas? Jeebus, I hope Toyota reads these boards... I mean, this kind of bug-finding is worth a LOT. Good on ya, narf!
If the cruise control lamp starts flashing, an error was found, and cruise will be disabled either for the remainder of the trip, or until the CC is turned off and back on. I'd have to check the wiring diagram. Sounds like the CC is sensing a false brake signal, knowing that the brake is not being pressed. The brake switch has 2 halves, one that is normally closed, the other normally opened. One operates the brake lamps themselves, one is used as a failure check as well as signalling for other things, such as CC.
Dan, the actual error condition has only happened once so far, but turning off cruise by hitting the flashers happens every time I hit it. I'm curious if it's just my car or all Prii that do the latter. If it's just mine it may have to do with the trailer lighting harness in my car. I can imagine a condition where it cross-feeds a voltage back from the turn signals to the brake light. If the cruise control uses brake light voltage to sense a braking condition then it could cause exactly what's happening. (grasping at straws here)
