| Diagnosis and repair of Heated Front Windscreen | |
Hi folks
I've been living without a heated front screen (HFS) ever since I bought the car. The recent weather has really brought home how essential it is! I struggled to find information on where the relay is, etc., so here's a write up of the fix. This is on a 2007 TDV8 Vogue SE.
On the 2007, if only one side of your windscreen is working, then the fuses and the relay are fine - it's a wiring issue or the screen is faulty. I had neither side working. I believe earlier models (2002-2006) had separate fuses and relays for left/right in the fuse box under the bonnet - I can't confirm this.
First off, I checked the fuses behind the glove compartment, 34 and 47. Both fine.
Next, I decided to look at the relay, because I thought it would be easy to get to in one of the fuse boxes. However, it is located on the passenger side of the car, behind the glove box. It's accessed by pulling off the plastic trim at the end of the dashboard. Certainly easier to get to than the screen cabling, so perhaps not bad as a next stop.
PowerfulUK have done a video on removing the end of the dashboard (first 20 seconds of this video):
Mine had an airbag switch on it, so I had to disconnect the cable to that after I had pulled it off. The relay is the one closest one to you. (See photo).
It looks like it's impossible to remove the relay, as it's blocked by the air duct. I took the vent and the trim off to gain access, but you don't need to do this. The relay and socket can be rotated towards you, so you can pull the relay from the socket. It's actually fairly easy to access. Five minute job to pull it, test and reinstall.
 | | Click image to enlarge |
 | | Click image to enlarge |
I pulled the relay, tested it, and found it was fine.
Next stop - the connections to the screen. These are behind the A pillar interior trims. There are two sets of connections, an earth and 12V live on each side of the screen. You will need to remove the trim on the side that doesn’t work. (The single relay feeds both sides).
To remove the trim, pry the Airbag symbol off at the top of the trim using a small screwdriver. There is a single 25 Torx screw behind this. After that is removed, you can pull the trim off – it’s just on clips.
When I pulled the trim off, it was easy to see my problem. On both sides, the earth cable was corroded through. Also, someone had been there before me. The connections were bodged on both sides (see photos). Having done some further reading, I think this would usually be one connector, not the two that I had. I think the bodger had cut the connectors off (fair enough if it's broken).
Incoming cables: The earth is brown, the power is black.
Screen cables: Both cables to the screen are black. I guess that's because it doesn't matter which is connected to +/-. The screen cables are attached to small square plastic connections, which have ribbons coming out of them that to the screen. These can be seen in the photos.
 | | Click image to enlarge |
Having found these, I tidied up the bodged connections with crimped bullet connections and reconnected the two earths using the same crimped bullets. The wires attached to the screen were difficult to access. They are quite short. I’m not sure if that’s because they had been cut by the bodger. It was difficult to get my crimping tool in there, but I managed in the end.
Now I had some decent connections, and before reinstalling trim on each side, I checked the power and the earth cables by starting the car (it needs to be running) and turning on the screen. I used my multimeter to check for 12V between the two cables, which I had! This bodes well!
I didn’t check for continuity through the screen, and now wish I had, but I know it’s getting power so if it still doesn’t work, it must be the screen! Now I just need a frosty morning to give it a test.
I hope this is of help to people.
Cheers, Rob.
 | | Click image to enlarge |
 | | Click image to enlarge |
 | | Click image to enlarge | '07 Range Rover Vogue SE TDV8
|
21st Feb 2023 10:28am
