Heated mirror glass issue

[Horrgakx]

https://ibb.co/sdSS891n

I bought replacement mirror glass (both sides) as the heating elements were reported as open circuit but I still don't think the heating side is working.

See the pic linked above. This is the old mirror on the offside just before I removed it.
I assume the heating circuit is the one to the right of the photo with the spade connectors, and the anti-dazzle is the plug to the left. Can anyone confirm this?

I'm not sure why one of the spade connectors is very very short, it made fitting the replacement very difficult with my sausage fingers. On the near side mirror the wires were the same length.

When I got the glass off I tested the resistance between the spade terminals and on both of the old glass it was open circuit. Unfortunately I didn't test the replacements before they went on.

As I said the heating still doesn't appear to be working. I think the fuse is ok but because of differences in the owners manual and the actual fuse layout I'm not 100% sure which fuse it is (this thread; https://forum.a8parts.co.uk/showthread.php?t=17310).

Also, are the old mirror glass' destined for the bin? Or would they be of use to anyone else?

Thanks

[steamship]

According to the current flow PDF here, this is what I found:

1. The anti-dazzle wiring is linked to Y20 in the following image. This is from page 118:



2. The heating wiring is linked to Z4 in the following image. This is from page 117:



Looking at the image you provided, I believe the heated feature are the two spade connectors on the right side of the photo, as the same feature on the D2 mirror on my car is located there, and mine definitely didn't have anti-dazzle. They are certainly dark coloured wires, but you'd need to clean them to see if they are indeed black and black/blue. As for the other connector, it looks like the wires are black/grey and black/green, although I always thought that the secondary colour was the minor colour i.e. the thin stripe.

As for the old glass, there might be someone out there who could make use of it, for the cost of postage, especially when some of these mirrors cost up to £500, depending on the functionality.

[Horrgakx]

Thanks for that! So measuring between the spade connectors on the mirror, the heating element shouldn't be open circuit? There should be some resistance?

[HPsauce]

Originally Posted by Horrgakx

Thanks for that! So measuring between the spade connectors on the mirror, the heating element shouldn't be open circuit? There should be some resistance?

Possibly incorrect! Only after you've chilled them in the fridge or freezer! Well certainly D2 mirrors work that way, with an inbuilt temperature switch (probably a bimetallic element).
Just checked my spare D2 mirrors and they are definitely open-circuit when warm and were working fine when fitted.

Though I could be wrong and the temperature control could be elsewhere. There's no obvious switch unit on the back of the mirror glass in the photo...

[Horrgakx]

The car was reporting them as open circuit. So if there’s something stopping a resistance showing across the terminals how does the car see anything other than open circuit?

[HPsauce]

Ah, missed that, cleverer more modern technology than the D2 mirrors!

The resistance should be "a few" ohms, of the order of 10 (maybe more maybe less), so if using a multimeter use the scale that goes up to 100ohms.

[Horrgakx]

"Cleverer / more modern" read as 'More complicated, expensive and more likely to f'k up" )))

[tc4332]

As a D4 owner, may I throw something at you?
Driver's door has a switch to select left or right mirror that must be in normal position for the heated mirrors to work. This fooled me for a few weeks in early D4 days.
Normal position is with the marker on the switch pointing towards the rear (or downwards). That depends on your eye height (Sean mentioned complicated).

[HPsauce]

As Ray observed, there's also quite a clue on the switch itself if you look closely at this slightly unfocussed image:

[Horrgakx]

You guys are effectively asking if I've turned it on? Thanks though
I need to find the fuse but it doesn't seem to be mentioned in the manual...