Rear Defroster

Could it be a wire disconnected or loose on the rear hatch? Other possibility is there's a break in the heating element on the glass. You might be able to use a multi-meter to troubleshoot the element as well as ensure power is getting to the rear defroster.

 

Yeah if completely not working, maybe some main connector wire is loose? If it was just a line or two, then more likely the problem would be a break in the line. There's kits for repairing that case, use conductive paint.

 

I believe there is a connection point on both the left and right sides near the plastic trim around the real glass that are visible when the hatch is open.

 

I didn't have to with my old Prius. Can another owner of a 2010 check to see if they see wires connecting to the defroster filament on the rear glass? If so, post picture of the connections?

 

I don't see any visible connectors on mine either. You're gonna have to pull plastic pieces off to find them. That said: if they're so well protected, makes me wonder if they're the problem. Could be. Or could be something in the rear defog switch?

 

Right. With your earlier post saying the LED light doesn't come on, I'd be looking at the switch, switch wiring, body ECU, relay ... if it were a bad connection back at the glass, the light would come on but the glass wouldn't heat.

-Chap

 

Someone with certain knowledge may chime in, but I wouldn't be surprised if it's in the instrument-panel junction box, under control of the body ECU, maybe in response to a multiplexed signal sent over from the A/C ECU. The wiring diagram will say for sure, and the repair manual will have good procedures for tracing your problem (since, as you might expect given multiple ECUs, maybe multiplex communication, etc., you might want a systematic approach to tracking it down).

I'm pretty sure Techstream (with a Mini VCI / VxDiag, etc.) will let you interrogate the A/C ECU, command the defroster on and off, and see what happens, to narrow down whether your trouble has more to do with the switch, or relay, or something further downstream.

-Chap

 

Yup, this assembly, $530 list, $380-ish new at discount, $55-ish salvaged.

The nice thing about knowing the price to replace the whole assembly is it puts an upper bound on what you might have to spend if you try to just disassemble it and clean up the switch, and end up bricking it. Then you can feel more free to just give it a try, and probably succeed.

-Chap