Heated rear screen battery drain

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leejunfan1

Member

Posts

42

Location

Kent

• Dec 11, 2015

• #1

Defender 200 TDI 1991

After many hours fault finding, the rear screen is drawing over 6Amps with engine off. I have removed the fuse and now the drain has gone, i have found a few bits on Google about it but none confirm if my year of defender has a relay for it that could be causing the short. Pulling the switch still leaves the drain.
Any info would be much appreciated!

 

J

jimwyllie

Active Member

Posts

158

Location

Worcester

• Dec 12, 2015

• #2

Do a Google search for defender wiring diagram, or try a Haynes manual. You will see from the diagram that there is a relay for the rear screen fed direct from the battery with brown wire (in general all brown wires are direct from battery, not controlled by ignition switch). If fuse is pulled this direct feed is cut. Feed to rear screen switch is ignition controlled, so if switch is disconnected it will not stop drain. There is also a voltage sensitive switch in circuit which is direct fed, but this is still connected when fuse is pulled so is unlikely to be your problem. Fault is therefore likely to be around your relay.

 

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leejunfan

New Member

Posts

1

• Dec 12, 2015

• #3

Have already checked Haynes and the workshop manual, only the workshop has a little PIC on the wiring diagram. Does anyone know where the relay is located and what part number it is?

 

J

jimwyllie

Active Member

Posts

158

Location

Worcester

• Dec 12, 2015

• #4

Can't help you with the part number, but the heated rear screen relay is behind the instrument panel according to Haynes.

 

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leejunfan1

Member

Posts

42

Location

Kent

• Dec 12, 2015

• #5

Thanks jimwyllie!

All sorted, the relay had come loose from there metal prong that held it to the bulkhead, picked it up to put it back on and drain went down to zero! I may have knocked it off when trying to find the dim dip relay. So dangling free behind the instrument panel for 6 months let it find something to short on.

 

Kwakerman

Well-Known Member

Posts

3,278

Location

Hampshire

• Dec 12, 2015

• #6

leejunfan1 said:

Thanks jimwyllie!

All sorted, the relay had come loose from there metal prong that held it to the bulkhead, picked it up to put it back on and drain went down to zero! I may have knocked it off when trying to find the dim dip relay. So dangling free behind the instrument panel for 6 months let it find something to short on.

Click to expand...

I don't think that will be the actual cause of your problem, more likely that the relay contacts had arced and welded themselves together, your fiddling around probably disturbed them and they freed up. Might be worth opening the relay, if you can, to see if the contacts are burnt. If they are replace it, while you might be able to clean them up with a bit of emery it wont be a long term fix and if it does weld itself together again you will end up with a flat battery just when you don't need it.