Thread: D2a Alarm fault after flat battery

HI, no fuse especially for the receiver, what you can do as first step to be on the safe side is to set the alarm on "always disarm with key", this will let you disarm the alarm with the key without needing the EKA all the time(this setting doesnt affect the fob function), then disable the passive immobiliser to make sure it will not kick in if the only key you have will loose syncronisation...as the receiver failed the RF test is possible that the receiver is gone(though i dont know exactly what that RF test is doing) but i know the BCU is sensitive to battery reconnection if it's not carried out as it should which means earth lead first...let's hope it's not a BCU problem... make sure you always save settings before you disconnect nanocom after you was connected to the BCU cos it used to have a mind of it's own and change settings without request... replace the receiver to rule it out cos unfortunately you can't do that other way... there are 4 slots for keys and you can see the codes and check if it matches with the code which is in the key one the back of the circuit board and if you find one which matches try to synk the key again in other slot and leave the good one alone

i presume you are sure that the battery in the fob is good though

Hi I did struggle over reconnecting the battery as the terminal bolts are very slack and took some effort to get tight enough and maybe the leads unintentionally went on and off in the wrong order.
I can control the bcu settings and power different items around the car no problem. So I dont suspect that. I cant understand why the receiver would die just because of the battery as it was working before.
Ive changed the setting you suggested so it shouldnt lock me out. Ive ordered a second key to program to see if that will work so I dont mess up the one key I have. But because the car cant detect the radio signal it might not work. I cant believe a disconnected battery can cause such a problem. I guess Ive not owned the disco long enough to be used to these things!

If the key code is the same as in the BCU as listed by Nanocom, and the key is transmitting , the car should start with the key and it should work the door locks manually.

There is a tester you can buy on Ebay that just tests for any frequency RF and will tell you if the key is transmitting when you hold it against it.

If all this checks out then it is probably the RF receiver which is situated above the B pillar in the middle of the roof.
This was the case with mine when I bought it.
Regards Philip A