Disco 1 300tdi es heated mirrors?.

Finally got my tab stuck back on the rear window heater grid but the heated mirrors never have worked.heated mirrors fitted and wired up but no voltage when the rear window demist is on i assume there's a relay is it twin circuit or would both fail together?.

mr glee said:

Finally got my tab stuck back on the rear window heater grid but the heated mirrors never have worked.heated mirrors fitted and wired up but no voltage when the rear window demist is on i assume there's a relay is it twin circuit or would both fail together?.

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Remove mirror glass and check for continuity on the heater element (with it unplugged from the car) and with the glass out you can also check for power.

As @lynall has suggested, pop the mirrors out and check the continuity of the heating elements and the power to them.
There's no reason at all to assume that a fault on one device will take out any of the other devices on the circuit. The only parts of the circuit which are "common to all" are the timer in the MFU, the relay K122 and of course the fuse.
If you've now got a working rear screen then you can rule all of that out and concentrate on each mirror.

Ok thanks will check that out this weekend to be honest never thought of checking the mirror elements as replaced drivers side earlier this year ( thank you white BMW 4x4 dick head) then again just because it's new doesn't mean it works.

If a continuity check of the mirror elements shows OK then the next check is going to be looking for power, use a test light or a multimeter.
If there's no volts then you're into the wiring. I tend to think in terms of where's the most stress, electrical or mechanical?
Mechanical stress could well be the bending of the wires over time causing a break somewhere in the rubber tube grommet between the door and the door pillar. Electrical stress could occur at any of the connectors becoming oxidised and failing.
Treat each mirror as an individual separate fault and start faultfinding from scratch on each side, and be prepared for a situation of having more than one fault on any one circuit, for example, both a faulty heater element and a broken wire somewhere.

@mr glee What did you use to fix the tab back on your rear window ? I removed the passenger door mirror tonight as it was not heating and the tabs are both missing. I have lots of spade connectors but I need to stick them on.

Cheers

The product is called frost fighter (tab bonding kit) only available from USA will cost about £45 including shipping.if it's the mirror tabs will be cheaper to replace me thinks.just an update o/s mirror bad contact cleaned and fixed n/s broken wire door to pillar many thanks for the help.

Thanks for that, I did look at that but it was the USA bit that put me off. The mirror is for my L322 and it's the auto dimming expensive one so want to try fixing it first.

I'll let you know how I get on.

Looks like a lost cause, can't get a decent reading on my meter on the heating element. Time to go shopping again