2005 Rear Window Defroster Issue

[gleaseball]

The rear window defroster on my 2005 Sienna quit working. Here are the following steps I have taken:
- Examined the connection to the window, and the connection is good.
- Ohmed out the connection to the other side of the window, circuit is intact.
- Disconnected the connector at the window and measured the DC voltage relative to ground with the defroster on and found it to be 0.6 volts. Measures 0.0 when the switch is off.
- Switched the relay underneat the dash. This had no change in behavior.

Does this 0.6 volts appear to be low? What value of voltage should I see out there at the connector? What else might be wrong?

[fibber2]

The rear defogger is something like a 150-200 watt system, so it must have a full 12v applied to the rear grid for it to function.
You said relay beneath the dash. I thought I remember seeing it in the fuse box under the hood?

[gleaseball]

Yeah, I know what you are referencing, but when I hit the switch I hear the clicking under the dash. The identification of the relays under the hood are pretty cryptic. I do know that when I pulled the relay under the dash, the LED on the switch quit working completely, and there was no clicking, so I am pretty confident I had the right one pulled.

I wanted to confirm that it was indeed 12V at the grid that was expected. Now that I have that confirmed I can dig in further. Thanks.

[fibber2]

The front defroster (by the wiper blades), outside mirror defroster & rear window defroster have common and separate components. Recheck - I believe that the underdash relay is part of the front defroster, while the rear defroster relay is under the hood. Not spent any time looking in detail, but that underdash one may also be part of the dash instrumentation while sending a signal to relay #2 under the hood to actually control the higher current line to the rear.

[datsa noydb]

I happened to be 'playing' inside my talgate this past weekend (installing trailer wiring), so I did some measuring for you. I also got about half a volt from the right-side window terminal to ground. HOWEVER, when I measured the LEFT side, I got over 13 volts. Which side did you measure? Evidently, the left side is power, the right side is ground.

.

[gleaseball]

Good advice, I will take a look today.

[gleaseball]

I located the relay under the hood and swapped it out with a known good relay. Turned the rear defroster on and measured the voltage at the rear window. 12.0 volts. Excellent. I could not locate a local parts store with the part, so I ordered it on line. So, things should be good once the new part arrives. Thanks.

[fibber2]

Ah, life is good! Glad to be of service. I bought my last relay off of eBay. $10 for an otherwise $50 Denso part.

Now if I could only get this Linux box in my lab to do these damn microchip maskset data conversions...... Hate hate hate having to work in quasi DOS.