Central locking/alarm fault

zaph · 9th December 2023, 12:27

Driving home last nigh though dodgy neighbourhood, so pressed the button to lock the central locking. The car wouldn't stay locked, thought nothing of it.

However when I got home it locked on the central locking and then a few minutes later the alarm went off. Did this a few times till I pulled the battery.

Removed and tested the bonnet switch, could find no faults and tried shorting the wires to test it. However with the switch out of the car, the car refuses to stay locked and I have interesting issues with the alarm going off.

For now I have pulled the battery to solve things. The plenums are cleared out regularly and no water ingress.

I have a new bonnet switch on the way but am less than optimistic it will fix the issue. I fear something far more serious maybe at fault.

To be fair, upto last night, the central locking and alarm have worked perfectly.

zaph · 14th December 2023, 15:27

Update, replacing the bonnet switch has fixed nothing. Which leads me to suspect the BCU has burnt out and gone haywire.

Can a T4 session diagnose such a fault? Is there such a magic machine anywhere in the Leeds area?

vitesse · 14th December 2023, 16:34

You’ve got BigRuss in Liversedge, not only does he have a T4 but more important knows these cars very well.

BCUs can fail, one of mine did, but I’m sure things will be sorted in record time.

Good luck

Mike Noc · 14th December 2023, 19:26

Try unplugging the lock/unlock switch on the centre console. With the car locked, if you try to unlock it with that button it sets the alarm off. Maybe a dodgy switch making when it shouldn't.

SD1too · 15th December 2023, 09:12

Quote:

Originally Posted by zaph

Update, replacing the bonnet switch has fixed nothing.

The doors also have similar switches Mark. Just a guess, but it might be one of those telling the BCU that the door is still open when it isn't.

Simon

DMGRS · 15th December 2023, 15:00

Mine was a door switch - they're built into the lock actuators.

p2roverman · 15th December 2023, 16:56

Quote:

Originally Posted by DMGRS

Mine was a door switch - they're built into the lock actuators.

Exactly the smae problem mine has just devoped.

Sometimes won't lock, the telltale beep ocurs.
Dash panel shows drivers door open when it is physically closed.
Interior light comes on while driving, and I think stays on while parked.
I dare not lock it, because if and when it does lock there is the risk the alarm will go off as happened last night.

Tried the advice of spraying WD40 or similar up into the lock but guess I'll have to strip the lock out and investigate.

All advice welcome.

zaph · 17th December 2023, 07:14

I have lubricated all the doors and replaced the console switch. However I don't think that is the fault, as there is no door open indication on the dash.

The alarm is going off when the car is unlocked and the alarm shouldn't be armed. Which suggests to me something more serious is wrong.

I have toaf and a cable for a laptop somewhere. If I dig it out, can it diagnose alarm faults?

Yorkshire GOC · 17th December 2023, 16:05

As suggested earlier i would visit Big Russ across the M62 at Liversidge - is a T4 wizard and knows our cars inside out - from what you say i suspect your immobiliser ECU has got water damage

9th December 2023, 12:27	#1
zaph Avid contributor Rover 75 Join Date: May 2015 Location: Leeds Posts: 135 Thanks: 0 Thanked 17 Times in 11 Posts	Central locking/alarm fault Driving home last nigh though dodgy neighbourhood, so pressed the button to lock the central locking. The car wouldn't stay locked, thought nothing of it. However when I got home it locked on the central locking and then a few minutes later the alarm went off. Did this a few times till I pulled the battery. Removed and tested the bonnet switch, could find no faults and tried shorting the wires to test it. However with the switch out of the car, the car refuses to stay locked and I have interesting issues with the alarm going off. For now I have pulled the battery to solve things. The plenums are cleared out regularly and no water ingress. I have a new bonnet switch on the way but am less than optimistic it will fix the issue. I fear something far more serious maybe at fault. To be fair, upto last night, the central locking and alarm have worked perfectly.

15th December 2023, 15:00	#6
DMGRS Discount MG Rover Spares Rover 75 CDTi, 2x MG ZS180 Join Date: Jun 2011 Location: Hythe, Southampton Posts: 11,320 Thanks: 456 Thanked 3,377 Times in 2,027 Posts	Mine was a door switch - they're built into the lock actuators. __________________ Your trusted MG Rover specialist! Tel: 02380 001133 / Email: [email protected] We now have a 'chat' function on our site for even quicker replies. Give it a try! Remember - discount code FORUM5 for 5% off

17th December 2023, 16:05	#9
Yorkshire GOC I really should get out more....... Rover 75 connoisseur se v6 auto Join Date: May 2014 Location: Hull Posts: 2,067 Thanks: 1,842 Thanked 623 Times in 469 Posts	As suggested earlier i would visit Big Russ across the M62 at Liversidge - is a T4 wizard and knows our cars inside out - from what you say i suspect your immobiliser ECU has got water damage __________________ She came off the Longbridge Line on 20-05-2003 The Silver Machine was the 13th of 160 Rover 75's to come off the production line that day and is the 100th of 527 Starlight Silver Rover 75 2.5 V6 Connoisseur SE Auto saloons listed in the build records produced world wide.

14th December 2023, 15:27	#2
zaph Avid contributor Rover 75 Join Date: May 2015 Location: Leeds Posts: 135 Thanks: 0 Thanked 17 Times in 11 Posts	Update, replacing the bonnet switch has fixed nothing. Which leads me to suspect the BCU has burnt out and gone haywire. Can a T4 session diagnose such a fault? Is there such a magic machine anywhere in the Leeds area?

14th December 2023, 16:34	#3
vitesse I really should get out more....... Rover 75 Saloon Join Date: Jul 2011 Location: Gävle Posts: 2,534 Thanks: 395 Thanked 823 Times in 652 Posts	You’ve got BigRuss in Liversedge, not only does he have a T4 but more important knows these cars very well. BCUs can fail, one of mine did, but I’m sure things will be sorted in record time. Good luck

14th December 2023, 19:26	#4
Mike Noc This is my second home Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009 Location: Hampshire Posts: 11,550 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	Try unplugging the lock/unlock switch on the centre console. With the car locked, if you try to unlock it with that button it sets the alarm off. Maybe a dodgy switch making when it shouldn't.

17th December 2023, 07:14	#8
zaph Avid contributor Rover 75 Join Date: May 2015 Location: Leeds Posts: 135 Thanks: 0 Thanked 17 Times in 11 Posts	I have lubricated all the doors and replaced the console switch. However I don't think that is the fault, as there is no door open indication on the dash. The alarm is going off when the car is unlocked and the alarm shouldn't be armed. Which suggests to me something more serious is wrong. I have toaf and a cable for a laptop somewhere. If I dig it out, can it diagnose alarm faults?