Disco 2 Fuse 20 keeps blowing after changing ignition barrel.

After having to change the ignition barrel on my Disco 2 this morning I can now start the thing without spending 5 minutes messing around with the key which is great.
What is not so great is that fuse 20 keeps blowing every time I try and start the thing now. Anyone have any ideas?

Everything looks ok and there are no obvious trapped wires etc. When replacing the fuse the clock display comes back on but as soon as I turn the key the backlight lights up and the display disappears and fuse 20 has blown again.
So at the moment I have no clock display, no radio and no interior lights and cannot work out why at all.

Which model is it and is the ignition barrel a land-rover one or aftermarket?

My Disco is a 51 plate bargain basement version of the TD5.
This is what has been fitted:
http://www.island-4x4.co.uk/steering-lock-ignition-switch-discovery-economy-d2lock-p-2496.html

Obviously not a Land Rover part but my budget only stretched to that unfortunately.
I still have the original barrel so in theory could look into transfering the limited electrical parts over if required.

That is the same barrel that I fitted to my Discovery 2. I didn't have any problems apart from a red alarm light comes on on the dash. This disappears when I press the fob unlock button. Their instructions said something about connecting a lead for the bulb if you wanted but I didn't bother and the bulb comes on anyway.

I've been having to use the unlock button on the fob for a while due to the key breaking (managed to slam it in the rear door by accident) and the only spare is a non fob key so that's fine. Just can't work out why the fuse keeps blowing. I'll be getting some more fuses tomorrow so I can hopefully track down the fault.

Your electrical problems would appear to be in the area of the illumination around the ignition lock barrel.
From the attached diagram from RAVE, the +12 volts is fed into the circuit at point "A" (bottom left) directly from the fuse F20. It is also connected in the fuse box to units like the clock and the radio memory. The purple/blue wire at the header (connection) C0294-10 is a switched ground supplied from the BCU so that the various internal lights come on and go off when the doors are opened. It's highly unlikely that the fault lies in the BCU, just consider the wire as a switched ground.



I don't quite understand what you mean about using the key in the door and "having to use the unlock button on the fob for a while due to the key breaking".

Unless some definite changes have been made to the oeration of the central locking system, the normal operation for the Disco 2 is to use the two buttons on the fob to lock and unlock the vehicle. Normally, the key is only required to activate the "Emergency Key Access" (EKA) process and of course to operate the barrel lock on the steering column.

Sorry if that wasn't clear, I meant I broke the key blade by slamming the rear door shut on it by mistake. The key I was left with didn't have a working fob in it so have been using the broken key as a fob, Annoyingly due to it not being close enough to the coil the red light on the dash will start flashing if I take too long to start the disco and I have to press the unlock button to turn off the immobiliser.

Thanks for the wiring diagram, I'll have a look tomorrow and see what I can find.

I have copies of the new blade in some spare fobs I have but the red dash light still comes on. I am not sure why the new barrel has affected the sensor but it isn't always.

Does the bulb light up at the ignition barrel?

Well firstly thanks for all your help, it has been appreciated.

Secondly I found the problem and the culprit was some fairly poor soldering on the key activated switch (NOT the ignition switch) on the new ignition barrel.
Where as the joints on the original switch are all hidden behind plastic the joints on the new switch they are not and the joint in question had so much excess solder it ended up being clamped against the bare metal of the ignition barrel body. On its own this was not enough to cause fuse 20 to blow though, only when the key was inserted into the barrel and the circuit closed would the fuse blow.

I ended up swapping the new switch and barrel light assembly over with the originals and fuse 20 is now sitting quite happily and gives me back the use of the clock, radio and interior lights.

I've let island 4x4 who supplied the ignition barrel know of the problem so they can test their stock and take it up with the manufacturers.

Good job. Glad you've got it sorted, but I would have been inclined to return the faulty part to the supplier so that they could see the problem for themselves.

I know what you mean, unfortunately if I sent it back I'd be without the only vehicle we have which isn't going to work too well.
I've sent them some pictures and if they want the switch part I can send them that as well. So far there doesn't appear to be anything wrong with the mechanical side of the ignition barrel so it can stay where it is unless I'm sent a new one first.

I am not sure what you mean by the key operated switch. There is a feed to the bulb and passive coil. The coil and bulb is still fitted in a plastic case in the original one I removed.

There are two plugs, one to the coil which needs to be transfered over to the new barrel and the second goes to the bulb and a switch which is in the ignition barrel housing facing the dash once its fitted. The switch is hiding under a small metal plate but it is activated once the key is inserted more than about 1/4".

IIRC the plug which connects to the passive remobilisation exciter coil has a shorting clip in it which bridges the pins in the connector when it's unplugged and must open when it's plugged in, it's an extra safety measure.... maybe it doesnt come undone when the plug is inserted and that would blow F20

I never looked behind the plate. I take it that this is the switch, except this is on the LR original.

That's the one.



On the after market one the joints where the wires are soldered to the switch are not enclosed in plastic, which on its own isn't a problem.



In my case however one of the joints had an excess amount of solder and was proud of the switch body ended up sitting on the ignition barrel casting causing the short.

So it ended up being something annoyingly simple but a just not what you'd expect the fault to be.

Even my soldering is better than that. Looks very amateurish.