Hi,

I have a 2005 e61 530d. The heated rear windscreen has recently stopped working.

I went out today with the muti-meter and checked the voltage across the fuse - 0 volts, took the fuse out and tested the voltage again by sticking the meter's pins into the fuse hoder sockets - still 0 volts (not sure if they were small enough to get a good reading or not).

However, lets assume that they did - why would I not be getting any voltage through to where the fuse is in the rear compartment? Is there another fuse that could have blown?

The light does come on when I switch the rear window heater on.

Any help or ideas much appreciated.

Thanks.

b.

 

The following diagram shows you the location of the connections for the various aerials in the window as well as the heating elements. If you can, it might be interesting to see what sort of voltage reading you get at the heating contacts at the window instead of at the fuse...

https://5series.net/forums/index.php?act=at...st&id=80017

(editted to include forgotten link to diagram... )

 

If there's no voltage at the fuse there will be none at the window terminals.

When you say there's no voltage across the fuse are you going across both the fuse terminals? As you won't get a reading that way. You need to have one of the meters leads on the fuse and the other on a ground point of the vehicle.

 

I was worried about the fuse test technique as well which is why I suggested a test that would possibly be easier to perform. It's not exactly clear how the tests are being performed so it's hard to tell how valid the reported results are...

 

Hi,

the first test was across the fuse terminals - so if I got a voltage there, then I would know that the fuse had blown. The second test was after taking the fuse out and then trying to get a reading across the contacts (where the fuse slots in). Nothing there either.

Anyway Rudy, where is the diagram you wrote about?

Thanks,

b.

 

Don't go across the terminals with or without the fuse it will prove nothing. You need to put one lead onto an unpainted metal part of the body i.e. a door hinge or screw head. Then the other end to the fuse terminal. This way your checking the fuse voltage to a good known earth.

 

The way you are testing assumes that there is a complete circuit from fuse through heater to ground. With circuit on, there should be 12V both sides of good fuse to ground. If there is no volts between fuse socket (fuse removed) terminals, then there is no circuit through the heater. This means that there is likely to be a broken wire and this usually happens when tail gate wiring has suffered fatigue. Replacing the wire is the only good cure and there have been other posts about this. If one wire is broken, then it is likely others will follow causing lights, central locking and wiper failures. I have had heater fail on E34 where both feed and return to ground wires broke at the same point and short circuited, blowing the fuse. Luckily the tail gate wiring on the E34 was a lot easier to replace than the E61.

It is not clear in the Handbook whether the heated rear window has a timed circuit which switches off after a while. This would involve a timer relay but I suspect this is unlikely to be faulty.

 

Sorry, I must have forgotten to paste it in originally...

https://5series.net/forums/index.php?act=at...st&id=80017

 

Thanks - its all a bit more complicated than I thought!!!

b.

 

Hi

I have a 2005 530D touring with exactly the same symtoms. I thought it would be a simple fix (fuse), but on BMWs nothing seems to be simple. I guess I'll have to book it in somewhere unless it mends itself. I'll post again if I make any progress.

T