Central Locking Issues - Fekin Pish Poor TVR Wiring Again!

[ChimpOnGas]

Oh how I love TVR wiring... NOT!

Yesterday the central locking system refused to unlock the car, it'll lock the doors alight but the unlock function is not operational, as you might imagine this is far from ideal!

So, with the door switches, solenoids, and locking mechanisms tested and ruled out it was off with the dash top to investigate, with the central locking relay case removed I can make the doors lock and unlock perfectly by applying light pressure to the lock & unlock contacts, but the unlock coil simply won't function when I press the key/alarm fob.

As we know our system will lock and unlock alternately with the press off the fob, in my case (as you would expect) after unsuccessfully trying to unlock the car the next press of the fob causes the system to lock the already locked doors, so I simply get a double 'Clack, Clack' sound from the door solenoids but ultimately the doors remain locked.

I clearly either have a relay issue or more likely my old Meta unit has finally taken it's last breath, I thought my fellow TVR masochists would be interested to know I've just bought a brand new Swiss made relay for £14.00 which I found on good old EBay, with these relays often commanding over £70 each I figured other's might want to know of it's existence?



This £14.00 relay has the same terminal layout, amp rating & central locking design function as the original Italamec central locking relay used by TVR, so I'm confident it's the right one.

http://www.ebay.co.uk/itm/222179157853

What I'm not 100% confident about is that my new relay will bring back my unlock function, but for just fourteen quid it's worth a punt before I'm forced to accept the expensive replacement of my original and paired Meta alarm & immobiliser units will be my only option

Fortunately David from HF Solutions is just up the road from me, so I suspect he'll be getting a call next week

http://www.hf-solutions.co.uk/

Rant over, apeart from getting yet another TVR issue off my chest I'm really just posting this in the hope the £14.00 central locking relay I found will help the TVR community save themselves a few quid?

Dave.

Edited by ChimpOnGas on Sunday 9th April 09:36

[ChimpOnGas]

Steve_D said:

It is the alarm that does the flip between lock & unlock.
For testing take a test wire connected to earth and touch it to pin 3 of the relay (with relay plugged into loom). This should do unlock. Touch pin 2 to lock.
This should prove if the fault is relay or alarm related.

Steve

Thanks Steve, I did do this but no unlock function . I tried a few ways to energise the unlock coil but could only stimulate the pulse with gentle physical figure pressure on the unlock points, actually this method gave me exceptionally reliable locks & unlocks so either the Meta unit isn't commanding the relay to to pulse or the unlock coil or the relay itself has failed.

I tested this and there's a definite +12.8v pulse coming out of the Meta unit on my meter when I press the key/alarm fob, but there's no pulsing of the relay's unlock coil. There's also small spark when I disconnect & reconnect the earth terminal at the relay. Reconnecting the earth wire also pulses the unlock coil in the relay indicting a small short, clearly there's a +V on the earth so I checked it and got 1.2v on my meter.

Flashing the earth wire against the relay earth terminal gives me not only the spark but dull click from the door solenoids too, It's normally not enough to give me the full unlock stroke from the solenoid but occasionally it is actually enough of a pulse to fully unlock the doors. If I examine the internals of my original 20 year old Italamec central locking relay it has a circuit board with various capacitors and diodes soldered to it, to be honest with the spark reconnecting the earth terminal and the results of the other meter tests on the relay it does look like I might me lucky and find my £14.00 relay will fix the issue?

TBH I got bored with it all and just went for a beer, I'll fit the new relay next week and go from there

Thanks again for your help

Dave.

[ChimpOnGas]

Like I said I got bored with it and went for beer, I'll have another look at it tomorrow, I do suspect the alarm unit too.

[ChimpOnGas]

I'll (properly) check the relay again tomorrow.

If as suspected my old Meta unit isn't putting out the unlock earth pulse a cost effective fix may be one of the many CDL units on EBay?



http://www.ebay.co.uk/itm/222462267509

It'll probably have double the range than the original system too.

[ChimpOnGas]

TV8 said:

Dave, did I see you had disappearing volts recently? On my last car, an alarm issue had similar effects pre sorting one of the relays, so not sure if you have sorted that or if the two could be linked?

Hi Graham,

I have been experiencing a low charge rate where my Canems software only ever shows a battery voltage of 13.63v, this is at idle and all the way to 4,000rpm and beyond, no matter what my engine speed is or how many electrical loads I switch on the battery voltage never goes above 13.63v.

I have no idea if it's linked or a coincidence thing?

Here's the history:

When I bought the car 8 years ago it was clear from looking in the file the previous owner had experienced lots of trouble with the Meta system, there was a big bill for reconditioning the alarm system from Offord TVR but when I investigated I discovered all they had done was cut the siren out and removed the indicator fuses from the Meta alarm unit under the dash.

Obviously like this when the alarm was triggered there was no siren noise or flashing of hazards, cutting out the siren and removing those fuses was clearly a right bodge, and especially shocking as Offord TVR had charged the previous owner hundreds of pounds for executing it. Although there was now no audible sign from the missing siren or visual sign from the indicators clearly the alarm was still activating as occasionally I would see the red LED between the speedo & rev counter flashing it's activation warning code at me.

The next thing that happened was my green LED light failed on my golf ball door release, this was some six years ago, then a couple of years later the button stopped working altogether, about that time I was forced to bypass the immobiliser on the higher amp starter solenoid circuit because the engine was occasionally refusing crank even after disengaging the immobiliser.

The bypass worked a treat but the button on the golf ball remained inoperative, I decided I could live with this but I'll be honest I've never really trusted my Meta system so eventually I decided to bypass it altogether putting the ECU circuit on a simple hidden manual immobilisation switch.

As you'd imagine the bypassing and hidden immobiliser switch has been completely reliable but last weekend the central locking element of my Meta system started playing up prompting this post, the car will lock just fine but refuses to unlock. If I open up the central locking relay I can lock & unlock the car manually by gently pressing the contacts on the lock & unlock coils but the system absolutely refuses to unlock the doors when I press my key/alarm fob.

I appreciate a new security system is what the car has really needed all long, I am fortunate in that I have David Fairclough from HF Solutions literately just up the road from my house, it may well come to this but as the work is likely to run into hundreds I can't help feeling as all I need is a tiny earth pulse to the unlock coil inside the central relay a more cost effective solution can be found?

Hence this idea for under a tenner....



Dave.

[ChimpOnGas]

Steve_D said:

ChimpOnGas said:

........

Hence this idea for under a tenner.............

Plus a boot release thrown in...result.

Steve

Exactly, hopefully it'll give the extended range, the boot release is just a nice bonus and all for £9.00 delivered.

TBH all I need is three negative pulses:

1. Doors Lock

2. Doors Unlock

3. Boot pulse

[ChimpOnGas]

Yes mate, with the new relay the car unlocks but now won't lock.

Basically the opposite to what it did with the original relay, clearly it's the Meta unit.

To be honest I expected to find this as I did a proper relay test after I'd hastily pitched the new one and everything pointed to the Meta unit.

I really should hand it over to David at HF Solutions but being incurably cheap I'm going to try the cheap module I bought from EBay. These cars really are let down by their poor wiring and the security system is the biggest weakness along with the inevitable earthing issues.

TBH my system has been dying slowly bit by bit for many years, it's 90's Italian electronics installed badly by Dorris at TVR some 20 years ago, it really shouldn't come as a surprise to me the last element (the central locking pulses) have finally failed.

I'm quite bored with it now, I'll have another crack at it at the weekend and report back here.

Good luck with yours, Dave.

[ChimpOnGas]

Cheers Graham,

I'll keep everyone posted on the new system, it was £9.00 delivered so let's not get too excited just yet.

However, in theory all I need is some reliable remote controlled earth pulsed to the lock & unlock coils in the central locking relay and it'll be all sorted and I don't see why modern Chinese electronics shouldn't be as good if not better than 90's Italian electronics that were installed badly by TVR and have been doing service for 20 years.

The problem with the Meta system was mostly down to the way it was fitted but the same system was used on Alfa's in the 90's which are famous for giving trouble, if you speak to the three TVR alarm specialists (HF, Carl Baker & Abacus Alarms) they'll all tell you the Meta system is the first thing in quality, personally I'm not convinced.

On the subject of reliability and Chinese electronics people should accept all our lives are dominated by Chinese electronics from our mobile phones to our televisions and everything in between. I have a Chinese made remote controlled battery disconnect device on my TVR (Battery Brain) which has been giving perfect service for some 5 years now.

Unlike the comically poor range of the Meta system I can connect and disconnect by battery remotely standing over 20 meters from the car, if the Meta system was that good why can't it lock and unlock the car until your right next to the car?

Personally I think the Meta system is poor and it didn't help the way TVR installed it, things have moved on and if the Chinese can produce cheap systems like my excellent Battery Brain that work from 20 meters why should I have to suffer worse performance from an expensive new Meta system? If I buy and have installed a new Meta system at great cost all I'm actually getting is something that was designed some 20 years ago, I'm not getting the first thing in latest technology that's for sure and I'm sure the range won't improve because when I quized David at HF on this he said it should be a bit better, this sounded like he was dodging my direct question 'will I get better range if I buy a new Meta system from you?' All modern cars have a remote locking system that works from a long way away, it seems ridiculous in this day an d age an alarm specialists can't give me the same on my TVR!?!???

I may still have to get David from HF in, all the respected local TVR specialist use him so I'm sure his work is good, but it does seem like a big bill just to get my car locking and unlocking properly.

Alan, that light on the golf ball door release was only ever green, and it's been my experience when you lose the green light it the beginning of the end for the Meta system. Slowly but surely since the day the green LED failed on my hijack button other elements failed too.

Best regards boys, watch this space.

Dave.

Edited by ChimpOnGas on Wednesday 12th April 06:41

[ChimpOnGas]

Here's another cost effective option for those suffering central locking issues on their Chimaera.

http://abacuscaralarms.co.uk/alarmshop/index.php?a...

Basically a remote controlled version of the central locking relay fitted as standard to our cars, if my £9.00 kit doesn't impress then this could be a neat and easy to fit hack to get my car locking and unlocking reliably again.

With two fobs it comes in at £120.00, there's no boot release feature but being from Meta you do get Meta fobs so it would keep my key set looking original.

I give you the Meta M20/12.

[ChimpOnGas]

Steve_D said:

It is the alarm that does the flip between lock & unlock.
For testing take a test wire connected to earth and touch it to pin 3 of the relay (with relay plugged into loom). This should do unlock. Touch pin 2 to lock.
This should prove if the fault is relay or alarm related.

Steve

Hi Steve, I've checked it properly now and here's what I found:

• Pin 2 (lock) on the CDL relay is correctly only earthing when I when I press the fob - black wire with white trace

• The car unlocks but because the car is already locked I get a double 'clack, clack' sound from the solenoid

• Pin 3 (unlock) on the CDL relay was found to be permanently earthed - white wire with purple trace

• The car refuses to unlock

I then went on to investigated wiring at both doors:

• With my meter taking a permanent live from the +V on the relay socket and using the rogue earth at pin 3 as the ground source I set about moving the wires at the solenoid wiring connector and even disconnecting the connector at the passenger door solenoid, my meter stayed fixed at 12.8V

• Leaving my meter connected in the exact same way I repeated the test on the drivers door, this time I could stimulate momentary drops in the voltage reading, I separated the connector and repeated the test which proved the issue sits somewhere between the the relay socket and the dashboard

I think I'm getting somewhere

Edited by ChimpOnGas on Friday 14th April 09:06

[ChimpOnGas]

Steve_D said:

There should be a plug at the immobiliser. Have you tried testing the CL relay with the immobiliser unplugged?

Steve

Hi Steve, there are two white connector plugs at the alarm unit under the dash next to the CL relay, as I understand it the immobiliser is buried behind the radio, I did try refitting the relay with both those white alarm plugs disconnected and it was dead.

With everything connected back up I get a click from the relay as soon as I refit it and dull clunk from the solenoid.

I also tested continuity on the white wire with purple trace (unlock wire) between the relay holder and the disconnected small plug then from the relay holder to the disconnected large plug and I got the beep from my meter in both cases, saying that if every point I'm testing is earthed which it seems to be all I'm really proving is I have continuity with earth.

Back on it tomorrow so any tips and pointers are greatly appreciated.

Thanks, Dave.

[ChimpOnGas]

Penelope Stopit said:

There is a very good chance that the fault is in the drivers side door harness, if the fault isn't in the door harness you could check to see if there is a door loom harness plug inside the car close to the A Post and disconnect it there so as to prove a point, also if need be mirror the same test at the passenger door, don't bank on the fault being at one door, after checking one door always leave it disconnected and then check the other door, there is always the possibility of there being faults at both doors
Is there a possibility that micro switches are also fitted and wired in each door?

Hi mate, here's what I did with respect to checking the door harnesses, and what I found....

ChimpOnGas said:

I then went on to investigated wiring at both doors:

• With my meter taking a permanent live from the +V on the relay socket and using the rogue earth at pin 3 as the ground source I set about moving the wires at the solenoid wiring connector and even disconnecting the connector at the passenger door solenoid, my meter stayed fixed at 12.8V

• Leaving my meter connected in the exact same way I repeated the test on the drivers door, this time I could stimulate momentary drops in the voltage reading, I separated the connector and repeated the test which proved the issue sits somewhere between the the relay socket and the dashboard

The short definitely exists in the harness between drivers door solenoid connector and the dashboard area where the alarm and immobiliser reside, I have checked the door pin switch and it seemed fine but I will check it again.

Personally I think the solution will involve me cutting the bad wire at each end and running a new one as unpicking the loom isn't exactly a practical option. Interestingly someone has been in here before me (must be over 8 years ago), it looks like at some time the drivers door solenoid was replaced because there are crimp connectors between the solenoid and its connector indicating a generic solenoid was used and the crude cut and crimp method was his way to cobble the original connector on the new solenoid.

Thanks for your input, Dave.

[ChimpOnGas]

Penelope Stopit said:

It's your call but, chopping a wire out and running a new one is a step in the wrong direction, you do need to find the fault, my reasoning...
If there is ever an electrical fault that is not found but by-passed there is a very good chance that should the fault be a wiring fault the area where the fault is can only get worse, this is why so many vehicles burn out
As I have stated above - Your car your call

Is there any possibility of the boot lock actuator having built in switching for the CLS?

If you have identified just one wire that's proven to be broken causing a short, a wire that's buried and bound up deep inside a completely inaccessible loom.... how would you suggest fixing it?

A: Rip the whole loom out and remake it?

B: Cut the bad wire at each end and run a new good one?

With respect I have to function in the real world and fix my central locking quickly so I can continue to enjoy the car again without spending days pulling the loom out of the car or paying someone a small fortune to rewire it, and for the sake of one broken wire. I appreciate cutting and replacing the bad wire is not text book but I'm not functioning in a text book world, I'm just trying to fix a simple CDL fault.

If you have a better solution please don't hold back explaining it.

Thanks again. Dave.

[ChimpOnGas]

Ribol said:

ChimpOnGas said:

Oh how I love TVR wiring... NOT!

The problem you have isn't "Fekin Pish Poor TVR wiring" it is your "Fekin Pish poor grasp" of how basic central locking systems work.

Many thanks for your delightfully respectful comments Ribol, you've been away for a while but you clearly haven't lost any of your special ability to make unnecessarily offensive comments.

Your behavior mirrors that of a bully, and it's worth remembering others who read your offensive comments will also see you in a similar light, if your intention is to present yourself as a rough uncultured individual you are doing a most excellent job. As we've never met and you've historically over many years taken a vociferous dislike for me, I can only assume you failed to be educated properly from an early age to treat others in a civilised way. This is not your fault so you have my deepest sympathy, but one can only hope its not something that will be passed on to a future generation.

Can I remind you his forum is not a competition, it's also not intended for ignorant ill educated people to vent their personal emotional issues by abusing others, if you consistently find it impossible to treat people with respect you really shouldn't be commenting.... however superior you arrogantly feel your knowledge is.

Please refrain from ever responding to any more of my posts.

Thank you, Dave.

[ChimpOnGas]

Steve_D said:

I know of 9 routes for the White/Purple.
1 A-30k on back of use box. this is to/from relay 6 interior light delay.
2 N/S Door
3 N/S Cill switch
4 Alarm
5 Alarm
6 Central lock relay
7 O/S Door
8 O/S Cill switch
9 Relay 15 which seems to be unused.

Steve

Thanks Steve, very helpful.

Dave.

[ChimpOnGas]

Steve_D said:

I've not found anything the white /purple does in the doors but there could still be a short in there.

Steve

Hi Steve, many thanks for returning to this and trying to support me.

The good news is..... I now have both lock and unlock...

The bad news is something remains very wrong with the wiring and I'm still searching for the source of the problem

While I've regained full functionality of my lock & unlocks I could only do so by disconnecting both door switches...

Also with my meter between the earth and the live wires on each switch I'm only seeing 7.9v?



So I went to the battery for a reliable earth and once more got 7.9v, I then took the live side from my battery and used the black door switch wire as the earth... and got a healthy 12.7v which indicates to me I've got good earths at the door switches.

In Summary

1. With the door switches connected the car will lock but refuses to unlock

2. With the door switches connected the only way to unlock the car is manually press the unlock contacts

3. With both door switches disconnected the car both locks and unlocks perfectly

4. The white wire with purple trace at each door switch only carries 7.9v

5. The white wire with purple trace at pin 3 on the CL relay also only carries 7.9v


Any ideas folks?

Thanks again, Dave.

[ChimpOnGas]

Penelope Stopit said:

Good find, your winning
I like you have no idea why the white with a purple unlock wire is connecting somewhere with the white with a purple door switches wires, apart from them being the same colour they should not be linked together and I wonder if a mistake has been made at some time and they have been joined together yet the joint didn't work but now does (only a thought)

From my investigations the white wire with a purple trace seems to present itself in five places on the car:

• Door switches x 2

• At pin 3 on the CL relay

• At the small white plug on the Meta alarm unit

• At the large white plug on the Meta alarm unit

I think you'll find this is TVR factory wiring, I'm not sure which of the plugs in in and out but I think it's fair to assume +v goes into the alarm unit then comes out to trigger pin 3 on the CL relay... but only when you press the key/alarm fob.

Penelope Stopit said:

There is a possibility that the wires are shorting together somewhere rather than joined together (door looms?)
I take it you are getting the 7.9 volts reading when the alarm/CLS is disconnected (if not disconnect and test)

I have now tested the white wire with a purple trace at:

• Both door switches x 2

• At pin 3 on the CL relay

• At the small white plug on the Meta alarm unit

• At the large white plug on the Meta alarm unit

In each and every location I am getting the same 7.9v reading

Penelope Stopit said:

If I was you I would be looking at the interior light circuit, the 7.9 volts could possibly be coming from the nterior light or interior light delay unit/relay Disconnect the interior light, perhaps the delay unit is built into the interior light and if it isn't you will need to find the delay unit/relay, whatever, disconnect interior lights and delays and test.

I thought the same, so I pulled the interior light delay relay from the fuse board and it made absolutely no difference.

Penelope Stopit said:

There is a very good chance that the 7.9 Volts at the door switches is correct, on a standard interior light circuit with no delay 12 Volt will be present at the door switches until they are earthed, If the 7.9 Volts at the door switches is correct, the fault is as you have found....there is a short or connection between door switches and the CLS white/purple wire

I have no idea if 7.9v is correct but I seriously doubt it, saying that I'm not claiming to be an expert on the Meta system and the way TVR wired it so I'm happy to be corrected. With the whole car being 12v and the Meta system being designed for a 12v vehicle why would this one and only wire show 7.9v not the 12.7v I see with everything else electrical on the car (or any other 12v car for that matter?).

What I can tell you is there's another permanent live wire at the alarm unit (black with white trace) that resides on the smaller of the two white plugs and right next to the 7.9v white wire with a purple trace, this black with white trace wire shows a healthy 12.7v as you would expect.



Now, here's a theory I'd be happy to have your opinion on

1. I'd assume the alarm unit has a small internal relay to perform this unlock function when it sees the IR signal from the key/alarm fob

2. Now lets assume the contacts on this little relay buried inside the alarm unit have fused themselves together

3. After years of operation the contacts have become pitted so also have a high resistance

4. With the contacts fused together that pulse unlock circuit is now incorrectly passing current on a permanent basis (white wire with a purple trace)

5. But its only allowing 7.9v across these contacts, the missing 4.8v being consumed by the resistance across the fused together contacts and covered to heat

What do you think?

Thanks again for trying to help me figure it all out

Dave.

Edited by ChimpOnGas on Saturday 15th April 17:02

[ChimpOnGas]

Moving on...

Steve_D said:

Quick thought.
When you are trying the lock/unlock have you got the doors closed? My thought being doors closed should give the same result as disconnecting both door switches.
Having spent some time working in the open doorways of many a Chim I know that brushing against the switch causes the locking to chatter rather annoyingly.

Steve

Hi Steve, can I ask a daft question?

"In your experience how many volts (if any) should I see permanently at my door switches when I put my meter between the two wires?"

Now for something I wasn't expecting!!!!

With both door switches disconnected and happy at least I can lock & unlock the car, I decided to go for a drive, the first thing I noticed when I started the car was the engine was racing at 2,000rpm

This was very odd as my Canems system is well mapped and has closed loop idle, TBH it never has this raised RPM problem but it was in cold start so I continued the drive until 85 degrees was showing on my laptop.

Weirdly the car felt smoother but with the engine fully warmed its was still idling at 2,000rpm, so I turned down the base idle and tweaked the PWM idle settings on the laptop and brought the idle back down to a 1050rpm idle where I like it.

Boy did she idle smooth, I mean super smooth and with the most stable AFRs I have ever seen by a good margin too, now I run 13.3:1 because it seemed to be what the engine wanted, but with this new found super smooth idle I thought I'd try the 14's to see if she'd take it. Normally anything leaner than 13.3:3 and the engine would start to hunt a little & running 14's was a no no but I now found I could dial in mid 14's and the idle remained beautifully sweet.

Happy with that I went for a drive, oh my God I naturally find I'm changing up at 1,300rpm as I pootle through town and I'm in fifth before I know it looking at a speedo reading of 30mph!!!

So I drive some more, this time leaving town I notice much crisper throttle response to go with the new found forgiveness at lower speed, as the road opens up I floor it in 3rd taking it to 5k.... then repeat in 4th.

I now have a big grin on my face, this mixed with a feeling of shock as the engine feels way way crisper and far more willing to rev. Back to town & calming it down the wonderful low speed drivability improvements remain and I return home to ponder the effects my wiring issues must have been having on my idle valve, injector openings and ignition system.

The differences were very pronounced indeed, basically improvements were noticeable in every way the car drives, I've now got no interior light when I open the door but I'm inclined to say "who cares"!

I get how voltages and poor earths can effect engine management systems but I never expected an improvement as big as this, to say I'm over the moon would be the understatement of the year

[ChimpOnGas]

SILICONEKID345HP said:

Why not upgrade the immobilizer and get rid of the alarm and have a remote fob fittede.

I'll happen Daz, eventually it will happen mate

[ChimpOnGas]

Steve_D said:

ChimpOnGas said:

.....In your experience how many volts (if any) should I see permanently at my door switches when I put my meter between the two wires?"..........

I've not had reason to measure it.
Being as the voltage will be coming from a combination of alarm, interior light relay or central locking relay there is no reason why it should be battery voltage and could have been a quite common switching signal of 5v
You could try unplugging two of the three and testing the voltage at the remaining unit then plug/unplug to test the next unit etc.

Steve

Thanks again for all your support Steve.

The voltage is 7.9v everywhere I find the white wire with a purple trace, this was tested with the doors shut and the white alarm plugs both plugged in and disconnected, the only way to kill the 7.9v was to completely disconnect both door switches at which point the door lock & unlock worked perfectly so it was clearly a switch issue all along. I really just need to understand if 7.9v is normal, if someone could check the voltage at their door switches I'd be grateful, if only to eliminate a question mark in my mind.

What I can say with 100% certainty is by simply disconnecting both door switches the lock and unlock function suddenly works perfectly, in fact the solenoids have never sounded so healthy snapping from lock to unlock in a very positive way, reconnect just one of the two door switches (passenger or drivers switch) and with the doors shut the fault immediately returns so at the very least both switches must be faulty. Obviously the door switches are just simple make & break devices, with the passenger switch disconnected and the drivers side connected (but hanging off the car) I was able to operate the switch by hand through it's full stroke ensuring the contacts were genuinely open & closed, visually the switch itself seemed to work fine but the fault remained even if I pushed the button right to the end of it's travel?

As you say the door switch behavior is such that with the door open you've only got to brush them with the very lightest touch and you hear the door solenoid chatter, I fitted new switches from TVR Parts a few years ago and they were like this from new. At the time I significantly extended the door buttons that act on the switches to make completely sure the switches were fully pushed in (which they most definitely were) but I simply couldn't stop my passenger door solenoid chattering, so in frustration one day I ended up simply disconnecting that switch.

I'll do a continuity test on the switches and see what I find, but for now I'm so impressed with the idle, drivability and throttle response improvements I'm inclined just to leave the dreadful things disconnected, clearly the alarm/central locking unit has been consuming enough current to significantly impact engine behavior in a negative way. The most noticeable change is my idle air control valve is now working as it should, the first start with the switches disconnected had the idle racing to 2,000rpm until I changed the settings in my Canems software. This makes sense now as for months now the idle valve has been been getting more and more unresponsive to any changes I made, clearly the PWM idle valve is one of the most sensitive components to any voltage/current anomalies in the car's wiring loom.

Obviously disconnecting the door switches isn't a permanent fix, but given the significant improvements in the way the car drives and the only downside I can think of is that my interior light doesn't come on when I open the door, this is the way it's going to stay (for a while at least). If I need light in the car I can simply flick the switch on the courtesy light itself as it still works manually without the door switches connected which is hardly a massive inconvenience in exchange for such significant engine behavior improvements.

Thanks to everyone who contributed in a possessive way to this post

Dave.