Heated rear window - not shown on wiring diagram?

@nate posted:

...didn't see a comment about the light blue wire so thought I'd offer an opinion at least.  With the red wire removed at the switch end, all the large blue wires in the first photo look 100% 'stock'  - - the image highlights the 'doubled' AC power block, and the 'single' connector normally used to power a dealer-installed radio, when fitted.  At least on earlier cars the OTHER end of that light blue wire went directly to fuse 9.  So if that fuse 9 connection was cut and a load was added between it and the fuse supply, 12V would go to the load whenever the orange switch was closed (i.e., grounded).

If somebody was adding rear window resistance heat to a Mangusta, that would be one EASY way to do it.   Unfortunately I have no idea if that was the factory's approach - - need input from the owner of another car with similar origins/manufacture to confirm whether or not the light blue lead is cut & re-connectorized near fuse 9.   But it's definitely a possibility!

Nate, I'd say the blue wire is original -it's integral to the loom, including running through the PVC sleeving. Having just resleeved the entire loom, there' no way you'd add wires afterwards!

The wire must be a feed for the heated rear window, especially after seeing Denis' photos.

Hi Chris, totally agree that blue wire is original.  While that wire 'normally' connects directly to Fuse 9 (....without the small terminal block....) this is how it COULD be used to power rear window heat, grounding through a dashboard switch.   

Of course power could come from any fuse, not just #9.  Any sign of additional wiring like this?:

Having become curious about 8MA1266 from reading the other string, just saw this in Provomo:

I’d love to access Provomo - sadly I haven’t received a confirmation email, and no reply from the contact email address listed. Shame as I’d like to contribute too!

Nate, There are a dozen cars with heated rear windows.

Hi Chris, I have owned 8MA 1298 in Australia for nearly 20 years.

It is in very good original condition, is RHD, and un-restored.

It has a Heated rear window with the Orange push button switch between the clock and ignition switch.

The picture below shows the back of the switch with the light blue wire, and I assume it is the positive that goes through the loom to the rear below the fuse box.

Then you can see the light blue wire emerging from the loom, into a connector and emerges as the light blue wire on the left that goes up to the heated rear window.

And the last picture shows the Orange Dash switch, to turn it on.

Hope this helps

Terry

So darn interesting...Terry, I assume that (since there is only 1 wire at the terminal block on the engine cover), that in your car the blue wire is the hot output of the switch; and that the red connection at the switch is from the cigarette lighter key (coincidentally, fuse #9! as Nate sees). The only other red wire I see in this area is the output from the ignition switch, but the radio/cigarette lighter are switched by the key thru the carello relays.

  Denis' picture makes sense for the indicator light (the near wire is almost certainly the feed, and I guess the celeste wire behind it forks to the indicator light).

  And the use of the Mamut terminal blocks for everything shouts 'factory...!' Interesting also the use of transparent covers on the terminals, still marked "Italy" but earlier colors were mostly black and 1076 has green covers (!)

btw M!ke and Nate, sure handy to have a colorized wiring diagram