Fob Programming 5AS

I am trying to program the fobs for a Rover 25 but it says that I should test the horn. The horn is original as came with the car and I can sound the horn from the buttons on the steering wheel but when I test the horn from the pscan I can hear a relay click behind the dashboard but the horn does not sound. Would I be OK to go ahead and program the fobs just with hearing the relay click and not bothering about the horn sounding?

It should be okay but you need to listen carefully as it will only click once and briefly.

Hi Everyone,
I need some help with programming a 2nd hand second fob for my 1998 MEMS1.9 5AS MGF.
I am in Sydney Australia and so am thinking 315Hz.
Bought x2 fobs from UK - returned and refunded after failure to program.
Perth wrecker sold me a 315Hz and when it didn't program sent me another and a 433Hz just to be sure.
Finally bought a $20 fob locally (with the 1239 on the capacitor).
All batteries have been new.
Always the same problem - the car's original fob will activate the horn after x8 'lock' pressing in 'Learning' mode but none of the other fobs do a thing!
What am I doing wrong?
Anyone?
Thanks for your help

From what I can see your fob that is working is 17TN type. 433 MHz is also 17TN type but for you beeing in Australia it will not work since you need 315 MHz one.
On the other side all 315 MHz fobs you have on the picture are 3TXA fobs.

Now, I do not know what type of Lucas 5AS box you have in the car, but If you do not need to press unlock button to start the car if you leave the keys in the ignition barrel after a while (or your indicators flash when you operate the remote) then you have later type Lucas 5AS box in your car and in that case you cannot use 3TXA fobs on that box. On that box only 3TXB or 17TN fobs with 315 MHz will work.

If I leave the keys in the ignition for a while in the off position and then turn the key the alarm goes off and I definitely need to press the unlock button to make it go away. Pretty sure that I can't start the engine either. Not sure about the indicators flashing though.
But you reakon the 3TXAs are of no use to me. Bugger!

I have seen 3TXA, 3TXB, 3TXC and 17TN fobs, so four different variants.

It isn't clear to me which variants are compatible with which variants of 5AS.

My current theory is that the early 5AS only works with the 3TXA, and that the later variants work with 3TXB through to 17TN. It would be nice to know for sure.

You can buy a fob tester from Draper (and others) quite cheaply which just flashes an LED if the fob is transmitting something. A friend of mine has one and I always use it to test that fobs are working before coding them as often they have a dead button or something.

There is a video on youtube now of me coding 5AS fobs here

Great video,
My programming worked just like that until the second fob bit!
Ok so with the car locked, pressing unlock makes the indicators light up once whilst the doors unlock and the immobilizer red dash light goes off.
If I leave the car unlocked for a while with the keys in the ignition (or not) the immobilizer will activate, red light on, and on turning the key, this activates the warning alarm (not the blarring of the car horn) and the engine will not start.
Pressing the unlock fob button results in the red light off, warning alarm stops and engine can start.

So I need the 315Hz 3TXB, 3TXC or 17TN?

(The three 315Hz 3TXAs and the 433Hz 17TN are exactly what I can't use!) You couldn't make this stuff up!!

And to further confuse me. My other MGF (don't ask!) has these two fobs that work perfectly! Much smaller batteries. What are these ones?

pdunkin wrote:

If I leave the keys in the ignition for a while in the off position and then turn the key the alarm goes off and I definitely need to press the unlock button to make it go away. Pretty sure that I can't start the engine either. Not sure about the indicators flashing though.
But you reakon the 3TXAs are of no use to me. Bugger!

Usualy if the car came with 3TXB or 17TN fobs 3TXA fobs will not work on these cars.

pdunkin wrote:

And to further confuse me. My other MGF (don't ask!) has these two fobs that work perfectly! Much smaller batteries. What are these ones?

I would assume that battery holders were replaced because of same reason with dry soldering of its contacts, since these battery holders certainly are not OEM ones. Battery that should go in the fob is CR2032 and this smaller battery is not that one.

pscan.uk wrote:

I have seen 3TXA, 3TXB, 3TXC and 17TN fobs, so four different variants.

It isn't clear to me which variants are compatible with which variants of 5AS.

My current theory is that the early 5AS only works with the 3TXA, and that the later variants work with 3TXB through to 17TN. It would be nice to know for sure.

You can buy a fob tester from Draper (and others) quite cheaply which just flashes an LED if the fob is transmitting something. A friend of mine has one and I always use it to test that fobs are working before coding them as often they have a dead button or something.

There is a video on youtube now of me coding 5AS fobs here

There are two types of Lucas 5AS boxes. Early type and later type. They differ from outside in fact that erly type has only one grey male connector and later type has two male connectors: grey and white one. Later types boxes has several additional functions like indicators flashing and coil around ignition barrel enabling disarming passive immobilisation when key is in close proximkty of ignition barrel (of course you need this coil around ignition barrel with later type box as well).

There are actually 5 types of Lucas fobs: 3TXA, 3TXB, 3TXC, 3TXD and 17TN.

You cannot code 3TXA fob to later type of box as it will not work, but early type of box should accept all type of fobs.
However, as I mentioned above, if car came with 3TXB or later fobs, then problems may occure that 3TXA fob will not be possible to code to that box.

I think the one that works is the "D"!