Heated rear screen

[john adam]

Hello, the heated rear screen on our 2.5 v6 has decided to stop working. The switch lights up but nothing at the screen.
What is the most likely cause? Looking at the wiring diagram there seems to me a number of fuses associated with the screen. If it is a fuse which one could it be.
All other systems work fine.
Look forward to the ever useful feedback, thanks.

[SD1too]

Hello John,

For a 1999 car, fuse link 7 (40 amps) in the engine compartment fusebox feeds the HRW relay and elements.

Ensure that your battery is fully charged since the manual says that certain equipment can be disabled if it is not. As the HRW is a very high current consumer, it's a probable candidate.

Simon

[john adam]

Thanks Simon, if that link is the problem are they available? Will check when the rain stops!
Our car is a late 2005 model, does that make a difference?

[SD1too]

Originally Posted by john adam

Our car is a late 2005 model, does that make a difference?

Ahh, thank you for that important information. Your profile mentions only a 1999 model. Do you have both or have you sold the earlier car? I did see the list of five cars in your signature but it's unclear whether you currently own all of them or it's a historic list of past vehicles.

Anyway, there are major fuse box differences between 1999 and 2005 cars but in this particular case it's still fuse link 7 for the HRW element. However I'll be very surprised if it's blown and you'll be able to tell visually. Beware that this part of the circuit is permanently live so if removing anything, disconnect the battery first (after waiting for the sat. nav. disc drive to shut down first).

You might also check for a poor connection at the screen.

Simon

[john adam]

Simon I hate to admit that I still have all those cars. Thanks for your very useful comments.
If it is not the fuse then perhaps it could be the filter adjacent to the rear screen.

[SD1too]

Well it's a very desirable collection of Rovers, particularly the P5B coupé.

Your best fault-finding tools are curiosity, observation and a multimeter to trace the 12v supply.

Simon

[john adam]

Hi Simon, I believe the 1999 car was one of the dealer launch cars in NZ. It was owned by BMW NZ for the first two years of its life. The quality is far superior to our 2005 car, inferior carpet, plastic grille badge etc.
Going back to my problem. Is the radio aerial linked to the heated screen, I only ask because the radio no longer works well.

[sln8458]

The radio aerial is integrated into the rear screen like the heating elements.

[TBennet]

OP, you say "nothing at the screen". I'm not sure if you mean that it's not warming up, or if you've actually tested for a voltage at the screen.

If you haven't, personally, before trying to trace the fault in any other location, the first thing I would suggest is that you ping off a bit of trim in the boot lid, find the connection plug for the heater, unplug it and test it with a multi-meter to see if you are getting 12 volts when the heater is turned on.

The reason I say this is that mine is doing exactly that. There's a supply coming to the heater, it just doesn't heat up.

[SD1too]

Originally Posted by john adam

Is the radio aerial linked to the heated screen, I only ask because the radio no longer works well.

Thanks John for another gold nugget of helpful information. The HRW elements double up as the radio aerial.

If you remove the D post interior trim panel on both sides of the car you may find a "filter, screen aerial" module on the RH side and an "isolator, aerial" on the LH side. Start by checking that the electrical connections are clean and secure. Details in RAVE are sketchy but if you find a thick brown/green wire that is the heavy current supply to the HRW elements. You can check that it carries 12v when the HRW is switched on with the engine running.

Simon