ibruceuk Posted February 6, 2012 Share Posted February 6, 2012 Hi there, This one has me completley stumped as the Rave diagrams and my Disco do not match! Just suddenly my fobs refuse to unlock or lock the doors. I have 2 and have put new batteries in both to no avail. I managed to get my EKA code from a LR dealer (for free) so at least I'm mobile. After some troubleshooting I found that both fobs worked fine if held right next to the alarm ECU in the passenger footwell, but still refused to work outside the car. So now I have a strange ritual of unlocking with the key jumping in and leaning to the passenger footwell while pressing disarm! (I disconnected the sounder so as not to annoy the nieghbours every time I go out) The fobs are the two button kind and I found the alarm ECU which doesn;t look like there is any water ingress. Whilst trying to find the antenna on Rave it is apparently pin 26 with pin 13 acting as a shield. On my ECU there is a solid core short length of red wire on Pin 26 and nothing on 13. So I assume the short red wire is an antenna. I extended this with some thin wire up the A-pillar and just poking out of the passenger door at the top. Sure enough if I hold the fob next to this wire it works! Has anyone come across this before? Why would they suddenly stop working like this? The only things done recently is add the winch and bumper and 2nd battery with split charge. I tried disconnecting all of this and still no difference. Help before I kill something! Cheers, Ian Quote Link to comment Share on other sites More sharing options...
Boydie Posted February 7, 2012 Share Posted February 7, 2012 My guess is the ariel is kaput. The sender unit of alarm ECU is located in the passenger side footwell and has an ariel that for all money looks like a loose wire that goes up inside the cover of the passenger A column and isnt connected to anything at its upper end. If it is go to your freindly wrecker and see if he will sell you one off a Disco in his yard. Quote Link to comment Share on other sites More sharing options...
teabag Posted February 7, 2012 Share Posted February 7, 2012 The wrong length of antenna wire will give a mis match in the send/receive frequency of the system.So do not cut or extend the wire. It's not unknown fot an electronic device that's powered up 24/7 in your case the alarm ecu to have a problem, you need to get it tested. Quote Link to comment Share on other sites More sharing options...
ibruceuk Posted February 7, 2012 Author Share Posted February 7, 2012 Thanks for the replys. I decided that I would try using the body for an antenna last night as a last ditch attempt so I shorted the short stump of wire to a nearby metal bracket and now the remote works from about 50ft away! As it's only a receiver and not transmitting it shouldn't do any damage by being shorted to earth... should it? Quote Link to comment Share on other sites More sharing options...
teabag Posted February 8, 2012 Share Posted February 8, 2012 Thanks for the replys. I decided that I would try using the body for an antenna last night as a last ditch attempt so I shorted the short stump of wire to a nearby metal bracket and now the remote works from about 50ft away! As it's only a receiver and not transmitting it shouldn't do any damage by being shorted to earth... should it? How do u think the 'rolling code' function works then? Quote Link to comment Share on other sites More sharing options...
MrKev Posted February 8, 2012 Share Posted February 8, 2012 Ok. 'Rolling code' works (to put it simply) by each end jumping to the next value in a secret list, the Rx is then expecting what the Tx is ready to send. By allowing the next, say, 32 valid entries in the Rx list, it is able to cope with the button being pressed when out of range etc. When you loose sync, pressing the button 4 times allows the Rx to 'work out' where it's supposed to be and re-sync. That's a simplified explanation - I'll happily write a whole lecture if required Three things could be happening. The Discovery seems to be well known for poor range on it's keyfobs. I recently had a problem with mine, where it started working very intermittently. The spectrum analyser showed the faulty keyfob to be still stansmitting at a similar level to a known good one, though I noted that the Discovery keyfob only transmitted breifly upon pressing the button, whereas many others makes transmitted continuously. Not having any other discovery keyfobs to compare to, I don't know what they're supposed to do, but I know which I'd rather it did. 1) The keyfob could be faulty, keyfobs get a lot of abuse being thrown around with keys. Inside the keyfob is a crystal which doesn't like too much mechanical shock. This could easily be compromised, causing the behaviour to become intermittent, or the operation to be off frequency such that the receiver is struggling to 'catch' the signal. Keyfob receivers are notoriously poor receivers anyway, at least on the earlier models. 2) The receiver could be having similar problems, or the antenna connections suffering, for example. Believe it or not, at radio frequencies, joining a bit of wire to an earth point does not necessarily short signals out, in certain circumstances it can actually help - many antennas are made of a loop of wire of a specific length going from the 'hot' pin of the receiver to earth. Certainly it is possible to improve the receiver's antenna - ultimately by having a dedicated antenna outside the vehicle, but of course, like all things, what landrover have done is a compromise against a number of other factors. What teabag says is right - the antenna wire is cut to a specific length to work with the receiver, though other specific lengths and configurations can be made to work too, but the detail of this requires more intimate knowledge of the receiver, or trial and error to get it right. What you have done seems to have helped, but it may not work so well in all directions around the vehicle, for example. This is probably not a problem, as you normally get in the drivers door, right? 3) You may be suffering from a new source of interference where you normally park. You would be able to tell if this is the case, as it would work fine in some locations, e.g. at home, but poorly elsewhere, e.g. at work. I went for the simple option first and got a new fob from www.remotekey.co.uk. Inexpensive, good service and effective. I was very pleased. Option 1 is by far the most likely, I think, but it looks like you've had some success with your method, and full credit to you for achieving a result. This may be start of a problem though, I do wander how long it will last though, so bear this thread in mind! Kevin Quote Link to comment Share on other sites More sharing options...
teabag Posted February 8, 2012 Share Posted February 8, 2012 The experiance I've had with my fob operating range over the 14 years I've had my disco is that if either the vehicle or fob battery are low then the distance decreases. To prove the point, I only use my disco at weekends as I work in London and also have a company car so when I come to unlock the distance to unlock is around 6 to 8 feet from the the ECUs location at NSF, but after a run the distance increases and can be as much as 15 feet from the front of the disco. So this I take is because the vehicle battery had lost some charge over the five days of standing still, when the battery is finally on it's way out I found there was very little increase in the operating distance after a run which can go on for a few months before the battery gives up. When there's an ever decreasing distances on the above I know the fobs battery is due for replacement that will always be some time around 15 months. I compaired all this with my spare fob which still new and unused other than being used for my tests but there's no change. My other car is an Accord and that can be locked/unlocked from around 200 feet at any time, not that I do that there's no need to, other than re setting a false alarm from a 10th floor building Quote Link to comment Share on other sites More sharing options...
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