Mg ZS+ 120 Reconected Battery Alarm wont Stop - Forums
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post #1 of 9 (permalink) Old 10-03-2017, 17:14 Thread Starter
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Mg ZS+ 120 Reconected Battery Alarm wont Stop

MG ZS+ 120 ,, car been stood for about 4 weeks battery had died so opened the door with key and popped bonet and charged the battery back up,,

The battery is charged and reconnected it too car straight away the Alarm sounds off and the Key Fob wont turn it off,, tried it multiple times,, locking the car with key ,,bonet down,, clicking key fob multiple times ,,,and key in ignition too start it,,,

Alarm wont imobilise,, Key Fob had a new battery too..

any help cheers ,,,Just got mi 4 digit code for the door lock too which i didnt already have but not tried it yet...
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post #2 of 9 (permalink) Old 10-03-2017, 20:17
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Suspect water ingress, especially if it's a mk2. Mines on its 3rd alarm! MG ZS Mk2 - Alarm Fault - Forums

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post #3 of 9 (permalink) Old 10-03-2017, 21:52
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Undo 2 bolts on expansion tank (10mm) and lift tank carefully to one side. This will expose alarm unit below, unplug and retry connecting battery. If no problems remove alarm unit and see if you can dry it ou but better still replace with a mk1 alarm as they are properly sealed.
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post #4 of 9 (permalink) Old 11-03-2017, 08:56 Thread Starter
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disconected alarm and connected battery ,, car still immobilised when trying too start it

The car is not responding too the Keyfob at all,, im just going too buy another battery for keyfob even though its 6months old too see if that works
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post #5 of 9 (permalink) Old 11-03-2017, 11:09
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Elliptical fobs both receive and transmit, but square (ish) fobs only transmit, and therefore require synchronisation.

If yours is the latter, the best way I've found is to place the key in the ignition, turn to pos'n II, and press unlock repeatedly... Four presses should be sufficient. Pressing lock and unlock alternately also works.

I've never seen an official method for re-synching, so someone else may be able help further if this fails.
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post #6 of 9 (permalink) Old 11-03-2017, 13:58 Thread Starter
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New battery in the Keyfob still not working, Keyfob is the oval one with 3 buttons ,, car still starts up for 10 seconds n stalls ,,disconnected the alarm under the expansion tank and tryed the 4 digit code in the door lock ,,but nothing still

car was working fine when parked up,, Car battery was dead for about 4 weeks ,,after a recharge ive got this problem alarm and immobiliser wont turn off when connecting the car battery,, keyfob dont do nothing...

Auto electritions picking it up Monday if not fixed,,,, CARS !!!!
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post #7 of 9 (permalink) Old 11-03-2017, 15:51 Thread Starter
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Update Fixed Tried everything past 2 days..dont know what changed though,

Alarm under expansion tank still disconnected,(couldnt deal with the noise),,Car battery just fully charged,,disconnected the charger ,closed bonnet ,locked car with key then opened it again with key ,didnt close the door just put key in ignition and turned to position 2 while clicking the keyfob,,hazards flashed in car and alarm light in dash started to work again,, Car started and stayed running ,,central locking back working again not connected the Alarm back up yet .....

All Good at mo,,, cheerz for help
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post #8 of 9 (permalink) Old 11-03-2017, 16:42
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Try disconnecting engine battery a few times, this often reboots the SCU.
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post #9 of 9 (permalink) Old 11-03-2017, 18:19
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The correct way to refit the SCU is ....

With the battery disconnected refit the SCU module.

Remove the Central Locking fuse (this is the main 12 volt supply to the SCU).

Reconnect the battery and then refit the fuse.

The SCU will beep when it powers up correctly.

There is NO re-synchronisation procedure for the Pektron system, if the module powers up then the fobs should operate immediately.

The Pektron fobs DO NOT receive any data from the SCU, it is a one way transmission from the fob to the module.

If a Pektron fob button, when pressed, brings no response from the SCU then please don't continue to press the fob buttons. Every time
the fob is used the shared Fob/SCU code rolls forward... if the fob code rolls too far forward without the SCU having kept up then there
is a chance that the SCU will no longer recognise the fob when the fault is rectified.
If this happens the fob cannot be synchronised.... time for a new fob.

Free Fob Programming and Diagnostics for forum Supporters... see here.

Pektron SCU/BCU Technical Information and Common Faults... see here.

Discounted Pektron SCU/BCU Relay Replacement for forum Supporters... see here.
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