MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGF Technical - Is this problem with my car security system happened to you??

Fellow F'ers, I've gone through the archives on this problem but I can't find anything which answers my question, so Im hoping that someone out there can provide some info or advice on what the problem may be. I suspect that it's something to do with the ECU and/or MEMS.

My problem, is that my car security system seems to be playing silly buggers. In recent days, my alarm has gone off for no reason. The car is parked in my garage and super-locked. For some reason, the alarm went off last Thursday at 4 am but then shut down by itself, as it would do if someone was trying to break into it. But no-one was trying to break into the car. Later that morning, when I was going (make that hoping) to drive the car to work, I noticed that the instrument panel LED wasn't flashing and I couldn't start the car. I tried the handset several times, but to no avail. I then tried to manually override the engine immobiliser as per the handbook, and that didn't work. I then tried to re-sync the handset with the car, but that didn't work. However, when I came home later that day, after trolling through the BBS archives, I checked the fuses for the alarm and found that they were all fine. So I tried everything again this time, finishing with re-sync'ing the handset, which worked. Thinking the problem was solved, I drove the car to work the next day without any problems. However, on Sunday all went to crap again.

Early Sunday morning, the horn just went off - I mean, a continuous blast, not the normal blast you get when the alarm goes off. Thinking the handset was still sync'd with the car, I used it to try and kill the horn thinking the alarm system was somehow responsible. No good. So, thinking I'd have to pull the fuse out, I went out into the garage and opened the boot andlo and behold, the horn stopped. I re-checked all of the fuses (all okay) and tried to re-sync the handset, which didn't work. I tried the manual override as per the manual and that didn't work. Obviously this car was not going anywhere and as I had to go out, I pulled the fuse for the horn so that if the stupid alarm went ballistic again, at least it wasn't going to freak out the cat or the neighbours. When I returned home, some 4 or 5 hours later, the LED on the instrument panel was flashing normally and I thought, beauty, got the car started and went for a drive.

I'm now back to square one. Sometimes the LED is constantly on, other times, it's not on at all. I've heard of tricks like pulling the fuse for twenty minutes to allow the electronics to sort themselves but as I expected, nothing.

I can't get the dealer to check my car at least for another 2 weeks because they're busy. MGR in Sydney are useless because they don't know but they did recommend that I take the car to my dealer which was really excellent advice on their part. I now have a car which is unreliable.

Is there anyone out there who has come across this problem who can suggest what the cause and solution may be? I think it may be the ECU. Looking at the workshop manual, it looks like the ECU is located just below the radio, about where the little fold out trinket tray is located. Would having a mobile phone (activated) cause any problems with the electronics of the ECU? We've also had some pretty cold mornings here (cold by our standards) of around minus 6 or so. The car is garaged but even so, I can't imagine that the cold would necessarily have anything to do with this especially whe you consider the cold winters that you guys in the UK and Europe have to endure.

If it is the ECU, is it a simple case of just replacing the ECU box, or is there more to it? Can my dealer plug in the testbook computer and run diagnostics to determine where the problem is and why?

Any help would be gratefully received.

Phil
Phil

Sounds as though it could be a fault with the boot wiring - it is not unkown for the wires to get rubbed in the loom/conduit where they come from the car body to the boot lid on the left hand side as you stand behind the car looking into the boot.

Ted
Ted Newman

But it shouldn't cause the other problems you have noted.

Does anybody know if the part is a straight swap, i.e. could you find another F owner to swap the unit (and fob) with and see which car starts misbehaving?
Will Munns

Phil,

Sounds to me like a problem with the Alarm ECU which as you say is behind the trinket tray. The fact that the LED is sometimes alight while the car is in motion and the horn blasted continuously suggests the computer in the ECU has problems. Also you couldn't get the alarm to stop with the blipper is another.

Opening the boot sent an override signal to the ECU, which it should anyway under normal circumstances.

Leaving a mobile phone (switched on) on the trinket tray does cause the alarm to go off every now and then. When the phone updates it transmits and sets off the alarm but it shouldn't affect the ECU permanently. It is possible that the computer in the ECU has crashed so perhaps you should try disconnecting it for a long period by unplugging it and leaving it overnight. I have had no experience of this problem before.

I am not sure if Testbook will be able to checkout these problems but try this procedure.

1. Ensure doors, bonnet and the boot lid are closed.
2. Sit in the driver’s seat and close the door.
NOTE: The next three actions must be carried out within 2 seconds.
3. Depress the driver’s doorsill button.
4. Switch the ignition on, off and on again.
5. Raise the driver’s doorsill button.
If the test mode has been entered correctly, the horns will give a short beep and the engine immobilisation buzzer will sound.
Opening either door, the bonnet or the boot lid, or operating the driver’s doorsill button, will cause the alarm LED to illuminate for approximately one second. If the LED does not illuminate, there is a system fault.
The volumetric sensor can also be tested while in test mode. To test the volumetric sensor, press the unlock button on the remote handset several times. The alarm LED will illuminate for approximately 1 second each time movement is detected in the vehicle.
The test mode is cancelled by switching the ignition OFF.


Good luck

Bruce
Bruce Caldwell

Bruce,

Thanks for the info and advice mate, I'll try your suggestion when I get home tonight. I've also been advised that it could be a short in the wiring somewhere as the interior lights do not always come on when I open the driver's door.

Ont he day that I though that I had solved the problem, I noticed a very faint smell almost like a buring smell but I couldn't say for certain if it was like the smell of burning insulation. Neither could I trace the source of the smell.

Apparently the computer system operated by the dealer will be able to test the wiring and possibly locate where the fault may lie, but according to this other guy (a techo from HQ) he didn't think it was the alarm ECU. Hopefully, this guy is right as it'll cost me $815 just for the ECU with labour on top of that.

Cheers,
Phil
Phil

Bruce, I haven't yet tried your suggestion but I did have a go at swapping the 15 Amp fuses just in case I had a dodgy one. Well, bugger me if it didn't fix the problem. The old fuse must have been dodgy but there were no obvious signs. I'm going to try that fuse in another slot just to see if there's any problem with it. I still reckon the wiring's buggered up somewhere 'cos I definately got a slight whif of a burning smell. But at least it seems to be working..... for the moment!

Cheers,
Phil
Phil

Phil,

got your email.
Strange trouble, I've never heard of before.
I have Bruce Email address at home and I'll forward to him.

I think your spot on the Alarm ECU and/or wiring down may be right. On the other hand another control part can be involved.
I mean the red colured box behind the fuse panel.
The MFU (multi function unit).
http://www.mgfcar.de/MFU/dk_DCP_6860.jpg

If you haven't got already the MGF wiring, then see at http://www.mgfcar.de/schedules for the Alarm ECU related.

Dieter
Dieter Koennecke

Dieter, thanks mate. I wasn't aware of the MFU so yeah, I'll check it out.

Cheers,
Phil
Phil

This thread was discussed between 23/07/2002 and 25/07/2002

MG MGF Technical index

This thread is from the archives. Join the live MG MGF Technical BBS now