MGF Central locking & alarm broken

Hi everybody

The car is a 2001 MGF VVC. I have a long-standing problem with the central locking & immobiliser, which now would need to get fixed.

Long ago, everything worked: the fobs, central locking, and alarm. Then, the locks started the grinding sound which meant they were on their way out. At some point the passenger door lock broke totally and got stuck everytime it was locked, so it was left open. Then, i guess both mechs were dead and pressing on the fobs worked only for alarm, and i used the key for operating the driver's door. Then the alarm started acting funny and i disconnected the horns after many false alarms in the night. And i used the car in that state for a while.

At this point, everytime i opened the driver's door with the key and got inside, i heard a whirring sound behind the centre console, like some plastic cogs turning in a loop, which to this day i have not understood (and still hear it every time). Couldn't find anything online.

This summer, i decided to fix it all: bought new door lock mechs (verified correct ones for my central locking) and installed them. Found a few broken wires in the trunk loom, and fixed them as well. Central locking still doesn't work. Pressing on fobs does nothing, activating the driver's door manually only acts on that door. Fobs don't activate the alarm anymore either. And now the immobiliser has also started to act up: at times once inside the car it blinks totally erratically in a rapid succession, there's the whirring sound going on behind the console, and i have to press the open button several times, or other times the lock button several times before the blinking goes to slow one-at-a-time blink and only then press the open button to deactivate the immobiliser. I've tried the re-pairing sequence for the fobs, many times, to no change.

It has gotten ridiculous. I normally search online until i find a solution, but i can't find anything other than fixing/swapping the lock mechs, which has been done. Or checking the boot wire loom, which has also been done (i cut & extended all the wires, to be sure).

Does this inspire any of you experts? Could it be the Lucas 5AS unit (that i also took out at one point to inspect if it had any burnt circuits, but it looked good on the surface)? Something else? What to do?

Thank you in advance for any pointers.

Have you put a new battery in the fob? :dry:

I would start with the fob batteries as well.

Yes, the batteries have been changed, in the midst of trying everything/anything. The fobs work for immobiliser (eventually), which to me felt like ruling them out (they work, even partially). The central locking however doesn't work manually, if a key or driver's door button is used, which feels like something else is going on.

So today i rechecked all fuses (which were fine), and ran the alarm self-test (http://www.the-t-bar.com/forum/21-aiketgates-guides/11201-alarm-system-how-to-test). Aside from the immobiliser alert sounding non-stop throughout the test (which i've not read is supposed to happen, but i tried several times and had it happen every time), it all checked fine as well.

I'm thinking the immobiliser & central locking + alarm are 2 different, although overlapping issues: i realised that i can seemingly activate the alarm either by lock button or key or remote, which causes a click-like sound from behind the centre console and the red light to come on. The indicators outside don't flash though. And when disarming the alarm, there's a longer click-like sound repeated a few times from the same place behind the console. Now that's the same sound i described in the first post as "a whirring sound behind the centre console, like some plastic cogs turning in a loop", which does sound like that as well (it's not a clean & clear "click"), but now hearing the alarm activation single-click version i realise it's the same click repeated.

So given there are problems with the alarm + central locking, i'm guessing that sometimes when i get inside the car the alarm is still on, and when i turn the key the immobiliser gets mixed in as well and that causes the need-to-press-unlock-several-times behavior. So i don't think (hopefully) i need to consider the immobiliser problems for now.

EDIT: i edited the post title to reflect that.

To recap:
- alarm works partially: it arms but doesn't blink indicators, doesn't lock doors
- central locking doesn't work at all: key (nothing), door button (nothing), remote (nothing)

Things checked/done:
- both door lock mechs have been changed for new ones
- all fuses are fine
- alarm self-test checks ok (except immobiliser alert sounding throughout the test, maybe "normal"?)

I had the driver's door wire loom check also noted on my list, but given the alarm light is armed/unarmed both by door button & key wouldn't that indicate the signal passes? What does this all say?

Whereabouts are you Sebastian, it sounds like a www.pscan.eu session would be useful.

Ok. During the alarm self test, the immobiliser alert should not be sounding.
It sounds as if you have a 5AS fault.

talkingcars wrote: Whereabouts are you Sebastian, it sounds like a www.pscan.eu session would be useful.

I'm in France, La Baule, on the west coast. I do have an OBD2 scanner in the car & an app, the pscan seems identical except it works also for pre-MEMS3 models, right? (or does it do additional magic over an OBD2 scanner?) Incidentally, i didn't even think of verifying with that, so much it seemed to be an electric fault which wouldn't trigger anything on the scanner. Will do a session tomorrow.

David Aiketgate wrote: Ok. During the alarm self test, the immobiliser alert should not be sounding.
It sounds as if you have a 5AS fault.

Gah. It does that every time, no mistake there. Ok, seems like we're zeroing in then. By curiosity, are there any links describing this or further symptoms to confirm the diagnostic? I was about to try tomorrow a 12V connection directly to the pink & orange wires (?) from the bigger 5AS socket to see if the central locking works, which i read somewhere else as a means of debugging the possible causes (the wisdom being that if that activates it then the wiring loom is not at cause, and that would add another pointer towards the 5AS). Are you guys by any chance able to confirm this theory, and the wire colors, before i burn the car down?

Thanks so much already for helping.

The www.pscan.eu has been designed to work with almost all the systems of the MGs and Rovers of the last 25 years so it will give you much more data from the Lucas 5AS than the average OBD scanner. It also reads the engine ECU, ABS ECU, SRS ECU and PAS ECU.

I have used mine on several vehicles and never fail to be impressed.

Ooh, am i reading correctly from the features that it could actually pair a new 5AS with the ECU, and also pair my existing fobs, if it ever came to needing to change mine? If yes then having a full diagnostic tool on top of that would probably justify the cost of getting one

Read all about it here!

sebastian wrote: Ooh, am i reading correctly from the features that it could actually pair a new 5AS with the ECU, and also pair my existing fobs, if it ever came to needing to change mine? If yes then having a full diagnostic tool on top of that would probably justify the cost of getting one

Yes, it gives you full access to the 5AS.