My 2005 Prius (86 K mi.) has a warning light on - brakes. Put on the scanner and came up with code P1116 coolant temp. sensor circuit stack for coolant heat storage system. Also C1378 - capacitor communication circuit malfunction. Any ideas? I'm just a shade tree mechanic but can usually fix stuff if I know where to start. I'm allergic to dealerships. Thanks, Bob
Doing a google search revealed this string here on PC. 2007 Prius P1116 code and coolant control valve issues | PriusChat Sorry I can't help you anymore than that. Ron
The C1378 is concerned with the auxiliary 12V power supply, located in the rear of the car near the 12V battery. It says that the communication from the aux. power supply and the skid control ECU (which is in the front of the car) is not correct. The trouble areas are the harness wires, the 12V aux supply, or the Skid ECU itself. Look for evidence of rodent chewing on the wires. Otherwise, you might have to continuity test the harness wires to make sure. If they are OK, then you might have to try replacement of the skid ECU with a used unit. I have yet to hear of a 12V aux power supply going bad here on PC, but that is a possibility.
Do you still have the original 12 battery? It is possible to confuse the computers into false codes if they do not get reliable power from the 12 volt battery. Weird stuff happening? MPGs dropping? Test The Battery | PriusChat
Thanks guys. This car was rearended and after repair I reinstalled the battery and didn't plug in that little connector. I bought it wrecked and ASSumed the lite was on when I bought it. Thanks again, Bob
I just discovered this code, plus C1371, C1256. No CEL, but accumulator runs often. Will check aux battery. Its a yellowtop less than a year. But connections can deteriorate wouldn't know where to begin the check for accumulator leak Posted via the PriusChat mobile app.
