[gazza190]

Update !!!!

This mod has had to go under further development. Once I have made the neccessary modifications I will update this post . As it currenty is this mod is not working and just extinguishes the hrw lamp and does not actually turn it off. Sorry for any inconvenience.




some members like it and others dont. the feature which means your heated rear window activates if the outside temperature is below 10 degrees. personally it drives me crazy and all i can worry about is wearing out my heated rear window, especially as tourer rear windows are harder to come by.

so i had a look at making some changes to stop this occurring. the mod which i ended up with basically disrupts the communication wire between the body control unit (bcu) and air con panel (atc) during cranking. this stops the temperature being read from the bcu by the atc and so the heated rear window will not activate automatically. if you wish to have it on you simply press the button and it will activate.

the mod works perfectly on my zt-t 190. i have not been able to test it on a diesel yet but im sure it will be the same. the one thing i can think of that could be different is if you have a fuel fired heater. it may not cut in and so a test on a diesel would be informative.

the mod was surprisingly simple in the end. the parts used were

1 double pole relay
1 diode
1 capacitor
some wire

you will have to excuse the poor quality and lack of pictures as i have been working on this in the cold rain and pitch dark . not ideal but this time of year is the perfect time to test this mod out.



first i located a suitable crank signal. the fuse indicated is in the passenger foot well fusebox and is for the crank signal to the immobiliser. it has a white/red wire behind. i spliced into the THINNER wire of the 2 to steal the signal. the fuse box is held in with 2 10mm nuts below the glovebox and pulls down easily enough to gain access







i then removed the atc panel by removing the four screws. i fed my splice wire past the glove box and into the atc panel area ready for use. i then cut the pink wire on the white plug which is the comms wire between the bcu and atc. i also spliced into the black wire on the same plug which gave me the earth i needed for the relay





a wiring diagram of the wiring i did. a bit rough but you get the idea. the capacitor is used to keep the relay open therefore disrupting the comms wire for a second or 2 longer after you stop cranking. if a capacitor is not used it does not work. the diode is used to stop the capacitor discharging backwards down the crank wire.



my finished project in place . excuse the bullet connectors but it was easier to switch wiring etc more quickly for testing.i also insulated it after and taped it to the atc loom to keep it neat and safe.







and there you have it. an easy, simple and cheap fix for this annoying habit our cars have. hope you enjoy and feedback would be appreciated