Keypad

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Woodie
Knows how to use the parking brake
Posts: 84
Joined: Sat Oct 20, 2018 4:45 pm

Keypad

Post by Woodie » Tue Nov 27, 2018 3:30 pm

Hi folks again still sorting little bits and pieces on my car and was investigating why drivers side rear window was not working.. I lifted switch panel and presto window switch unplugged, plugged back in and away window went perfick as they say... Now while doing this i spotted the connector to the immobilizer keypad is laying unplugged... Looking through posts on here i am reluctant to plug this back in as the car starts fine except the dodgy relay thing.... Can you give me your thoughts on this as one comment i read said this may well cause future problems... Thanks again in advance
Richard

xmexclusive
Global Moderator
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Joined: Wed Apr 15, 2009 8:11 am

Re: Keypad

Post by xmexclusive » Tue Nov 27, 2018 5:07 pm

On an XM fitted with a working keypad immobiliser knowing the current 4 digit security code is a critical feature.
That security code will almost certainly have had to be known to the person who unplugged the keypad.
The keypad unplugging then had to be done with the engine running.
This process will have reset the engine ECU so that as the ignition is turned on the ECU misses out the keypad code check in the start up routine.

Plugging the keypad back in and switching the ignition on will reset the engine ECU to include the security code check in the start up routine.
Once this is done there is only one easy way back, you must know and inset the correct security code before your XM engine will start.

My advice is:- DO NOT RISK LOCKING OUT YOUR IMMOBILISER.

I could add a lot more detail on fixes but this varies by XM age and model.
PM me with details if you want to go any further.

John

Assich
Has changed a sphere or two
Posts: 312
Joined: Sat Apr 25, 2009 7:43 pm
Orga / RP numbers: 5678
Location: Moray

Re: Keypad

Post by Assich » Tue Nov 27, 2018 7:07 pm

Leave unplugged. Simples. I do have a keypad with known code in my spares bin. Was planning on putting the fully working flap top on ebay but have no such plans for the pad.

xmexclusive
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Joined: Wed Apr 15, 2009 8:11 am

Re: Keypad

Post by xmexclusive » Tue Nov 27, 2018 10:59 pm

To be clear.
On an XM the keypad does not contain the security code.
The last two security code entries used are stored in that Engine ECU.
At ignition switch on the ECU checks for keypad presence.
If it sees the keypad present the ECU waits for correct keypad entry before releasing the immobiliser for engine start.

If you change an engine ECU the stored codes move with each ECU, they are not in the keypad and do not stay with the car.

John

Woodie
Knows how to use the parking brake
Posts: 84
Joined: Sat Oct 20, 2018 4:45 pm

Re: Keypad

Post by Woodie » Wed Nov 28, 2018 12:07 am

Ok thanks... Any way of wiping the codes?
Richard

motorgnome
Knows how to use the parking brake
Posts: 82
Joined: Sun Aug 26, 2018 12:36 pm
Orga / RP numbers: Silicon Grey RP5058
Silver spares car RP4957

Re: Keypad

Post by motorgnome » Wed Nov 28, 2018 4:45 am

Good to read this.. On my series 1, if I un plug the keypad whilst running , the engine keeps running, but will not restart without re-plugging the keypad & inserting the code. I am running mine in the 0000 mode right now as it is not on the road as yet (soon). I do have the code, so I am not too worried (except that one day, the system will fail & leave me stranded)

xmexclusive
Global Moderator
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Joined: Wed Apr 15, 2009 8:11 am

Re: Keypad

Post by xmexclusive » Wed Nov 28, 2018 1:26 pm

Hi Richard

The codes are stored in a type of memory chip that does not require a power supply.
Those chips contain other data essential to running the engine so wiping the chip does not help.
For a code locked 2.5TD I have replaced the memory chip with one programmed to contain ex factory data.
This restarted the ECU as though from new and I could set new codes but it did not eliminate the keypad function.
Specialists can reprogramme the engine ECU controlling chip(s) with programme changes to eliminate the code check.
This typically costs £100 plus and not all specialists are now willing to work on such old technology.

Hi motorgnome

Each XM model has variations in features.
Unplugging of keypad does not work for all.
The advice about not plugging back in if found unplugged does apply to all.

Some Mk 1 had an early version of the keypad system.
These had an 0000 code setting which was the immo disable function, a feature that was not continued on any Mk 2 XM models.
Setting the garage code as 0001 was to avoid having to give out your personal code for maintenance work.
The immobiliser was still operative with the 0001 code.
From 1995 the garage code changed to 1111.
Late in the XM production a further change allowed the garage code to be set to any code except the current user code.

Early ECU's had a 1 minute time out after 3 wrong keypad attempts.
Later in production this time out was changed to 1 hour.

John

Woodie
Knows how to use the parking brake
Posts: 84
Joined: Sat Oct 20, 2018 4:45 pm

Re: Keypad

Post by Woodie » Wed Nov 28, 2018 6:12 pm

xmexclusive wrote:
Wed Nov 28, 2018 1:26 pm
Hi Richard

The codes are stored in a type of memory chip that does not require a power supply.
Those chips contain other data essential to running the engine so wiping the chip does not help.
For a code locked 2.5TD I have replaced the memory chip with one programmed to contain ex factory data.
This restarted the ECU as though from new and I could set new codes but it did not eliminate the keypad function.
Specialists can reprogramme the engine ECU controlling chip(s) with programme changes to eliminate the code check.
This typically costs £100 plus and not all specialists are now willing to work on such old technology.

Hi motorgnome

Each XM model has variations in features.
Unplugging of keypad does not work for all.
The advice about not plugging back in if found unplugged does apply to all.

Some Mk 1 had an early version of the keypad system.
These had an 0000 code setting which was the immo disable function, a feature that was not continued on any Mk 2 XM models.
Setting the garage code as 0001 was to avoid having to give out your personal code for maintenance work.
The immobiliser was still operative with the 0001 code.
From 1995 the garage code changed to 1111.
Late in the XM production a further change allowed the garage code to be set to any code except the current user code.

Early ECU's had a 1 minute time out after 3 wrong keypad attempts.
Later in production this time out was changed to 1 hour.

John
|Cheers John.. Looks like i shall be taping off the plug with a warning "Do not plug in" just in case some kindly mechanic on seeing it decides to "help me out"...
Richard

motorgnome
Knows how to use the parking brake
Posts: 82
Joined: Sun Aug 26, 2018 12:36 pm
Orga / RP numbers: Silicon Grey RP5058
Silver spares car RP4957

Re: Keypad

Post by motorgnome » Thu Nov 29, 2018 2:17 am

Good information John...Thank you

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