Heated rear screen

I couldn't find the circuit in the 550 diagrams, but it's probably similar to the 456M...

After power leaves the rear screen/mirror heat relay (on the main passenger footwell relay panel), it goes to a big splice (location unknown).

The splice feeds:
1) the dash indication circuit (annunciator light and digital display),
2) the mirrors via the big door plugs, and..
3) the rear screen via a big connector near the front of the centre console and then to the rear screen connector.

Relay panel and possible plugs which go to the rear of the car:

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Rear screen plug (one of the two circled, I believe)

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Check your mirrors for heat. If ok, the problem may be downstream of the splice. I don't think any of the wiring will be easily accessible. You may have to remove the rear pillar trim (if possible) to get to the window connector to check for power.

Plug 280 is the radio antenna pre-amplifier. I see there is a ground/earth nearby. I don't know if any of the devices in the top left hand corner use this ground. Is anything else in that corner not working?

Please let us know how you go. I spent a few hours looking into this.

 

For general information:

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