In the electrical diagram pdf under the heated elements (such as mirror or the rear window) it has a current indication.
1) Is this how many amps that component is supposed to draw? 1 amp times 12 volts equals 12 watts, which hardly seems like enough to defrost the rear window.
2) The rear window and each of the wing mirrors are listed at 1 amp but they all run through a 30 amp fuse, that seems way to high if they are only supposed to draw 1 amp each.

Thanks for any insight or confirmation (I’m trying to troubleshoot the heater elements, if you can’t tell!)

 

What do you see in the wiring diagram that indicates amps? Other than the size of the fuse, which is 30 amps?

 

The size of the fuse is what I’m referring to. I don’t know if there is any standard regarding the correct size fuse but 30 amps for a 3 amp (supposedly) circuit seems way too high.

Ultimately, and I apologize for not phrasing it clearly on the first go around, what I want to know is how many amps should be running through these circuits? My rear screen takes forever to de-fog. I’m planning to measure the current and want to know what I should be expecting.

 

Alternatively if someone with a well functioning rear defroster wants to undo the terminals and measure the resistance across the grid, that would work for me to!

 

Any electrical heating source is going to have high amperage.
The Disco is old. My rear defroster takes a while to work also. Throw a towel over the windows at night or park it in a garage/overhang.

 

Surprisingly, I see "1 AMP" in the right side box for "Heater element rear screen"
I would prefer to see "x Amperes"; but if the british are also into mutilating words, well, let them have it their way.

 

Maybe I'll do that this weekend. I could also connect the multimeter in series and measure the amperage directly.

Damn. I overlooked that.

 

That's exactly what is causing the confusion for me, what else could that 1 amp mean other than "this element is supposed to draw 1 amp at a 12v nominal voltage"? If you look at the heated mirrors they also say "1 amp" in the little box, that's where I got the circuit total of 3 amps from.

 

Okay, here are the results.

I connected the multimeter in series in the heated rear window circuit, started the engine, pressed the switch and read the current draw. It was drawing about 9.25 amps.

I also connected the multimeter across the two heated rear window connectors to read resistance. The reading was 1.7 ohms.

Hope this helps.

 

Thanks! That makes sense to me, a 9.25 amp draw is way more reasonable than a 1 amp draw, so I'm probably misinterpreting the electrical diagram manual. The resistance reading is useful too as I can double check to make sure that all of my traces are intact (more traces, less resistance, more current- so that should be useful). I already know that I have at least 1 that doesn't work. Thanks again!