Datatek
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Why do you think that I wonder?
P38A 2.5 DHSE Electrical
- Thread starter Jomac
- Start date
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Datatek
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The P38 diesel is not CANBUS
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Obviously this lad is going to continue with his efforts no matter what you or i say so let him get on with it.
Datatek
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My view exactly.Obviously this lad is going to continue with his efforts no matter what you or i say so let him get on with it.
He seems to have done no research into the BECM or even had a look at RAVE.I would definately listen to the advice given by multiple, knowledgable people in previous replies to this thread.
Having said that, If you do want to proceed with your experiments (and If like me you really love to get upto your armpits in broken electronics) then I would take into account the following :
1. Forget CAN bus for now. The P38 uses a mixture of KLine and Serial comms at custom baudrates.
2.In a lot of other vehicles, the signals to monitor and control door locks/switches or solenoids run directly from the doors themselves back to the ECU/BCU. Not the case with P38 as they use an "Outstation" model where the door signals are fed to a small ECU in each door and then back to the BECM via a serial link.
3.In a lot of other vehicles, the ignition key contains either a wedge/glass pellet transponder or a transponder IC and associated coil. The ignition barrel has a corresponding inducton coil in order to perform bi-directional comms with a suitable ignition key.
NOT so with the P38. It uses the barrel ring only to induce a signal into the key which causes it to act as though one of the keys buttons has been pressed.
Having said that, If you do want to proceed with your experiments (and If like me you really love to get upto your armpits in broken electronics) then I would take into account the following :
1. Forget CAN bus for now. The P38 uses a mixture of KLine and Serial comms at custom baudrates.
2.In a lot of other vehicles, the signals to monitor and control door locks/switches or solenoids run directly from the doors themselves back to the ECU/BCU. Not the case with P38 as they use an "Outstation" model where the door signals are fed to a small ECU in each door and then back to the BECM via a serial link.
3.In a lot of other vehicles, the ignition key contains either a wedge/glass pellet transponder or a transponder IC and associated coil. The ignition barrel has a corresponding inducton coil in order to perform bi-directional comms with a suitable ignition key.
NOT so with the P38. It uses the barrel ring only to induce a signal into the key which causes it to act as though one of the keys buttons has been pressed.
tarphenry
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Theres some smart buggers on here ,isnt there
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Smarter than the average bear BooBoo.
martyuk
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In addition to the above. There are no "unlock" signals sent from the BECM - it handles all of that internally.
The microswitches in the drivers door, as you have found are:
Door Ajar Switch: Found in every door, and feeds an input into the BECM if the door is open/closed
Key Switch: Found only in the drivers door, this triggers whenever the key is turned from the central position in one direction or the other.
CDL (Central Door Locking) Switch: Found in both front doors, and will feed a locked/unlocked signal INTO the BECM to tell it if the door has been locked or unlocked. The BECM will then use this (to trigger the central locking for other doors). If triggered on it's own with the vehicle in an unlocked state, then it will just lock the doors and NOT set the alarm (eg if you are in the vehicle and lock the doors for personal security etc). If in the drivers door the BECM sees this switch change state ALONG WITH the key switch, it will assume that the vehicle has been locked/unlocked with the key in the door and arm/disarm the alarm/immobiliser accordingly.
For what you are trying to do, you will want the passive immobiliser (coil around the ignition) DISABLED as when it's enabled, it will automatically time out the immobiliser when the vehicle is unlocked, and this will then be reset when the fob is put back in the ignition - it is detected with the key in switch, the BECM pulses the coil, and the fob sends an unlock code to re-mobilise the vehicle, or you have to press the unlock button again to resend a valid code. If you are planning on doing away with the current fob, then you want the passive immobiliser disabled, as without a valid fob code being transmitted, the vehicle will stay immobilised and won't start. The aftermarket system won't be able to spoof that either.
You wouldn't need to leave the key in the ignition in the ACC position either, as it's plenty easy enough to bypass this to make it think that a) Ignition Pos I is on, and b) the key isn't in the ignition. The other problems you will have to overcome include...
- The P38 being a power hungry beast at the best of times. with ACC on (which is an input to the BECM, it then does a load of things with that information - it isn't just a simply relay output) other things are powered up under the bonnet and in the BECM, so you will have an additional power draw there, and the BECM is unlikely to go to sleep.
- If you make it so the key in ignition warning is disabled, then the BECM will permanently think the key is removed - which gets rid of the annoying warning, and will let the vehicle lock/alarm via input triggers to the drivers door - which is what it sounds like you are trying to do. The problem I can see with this is that it's probably going to throw up an "Engine Disabled" warning and not send the immobiliser code to the engine ECU to allow starting if it DOESN'T think the key is in the ignition. If it hasn't detected the key in the ignition, and you then try to go to position II or III to start, then it will probably think it's being stolen. I haven't tested to see if this is an actual problem before, but it's something to keep in mind.
- If you keep the key in ignition switch enabled, to make sure it starts and doesn't think it's being stolen, or keep the key in the ignition, then you will have the issue of the BECM not allowing the rest of the vehicle to be locked/alarmed, as it's a feature to help stop you from leaving your keys in the ignition and locking them in the vehicle.
A lot of the inputs it sounds like your remote system and push button starter need are possible to spoof, but they're all on the input side to the BECM, rather than the BECM sending out a 'locked/unlocked' signal to anything - as it's all handled internally.
I hope that helps explain a bit more of the P38 system to you - my advice, from someone who works a bit on BECMs and locking/immobilisation issues on P38s is in line with the others on here.... get the original system working as it should, as it is fairly robust - especially now most of the foibles of it are known and there are either fixes or upgrades now available from the aftermarket receivers to block RF interference - or the inline filter option that myself and another P38 owner make, or rebuilt door latches to make sure microswitches are working as they should.
I'm not saying that aftermarket projects aren't fun to work on - I've done a load to my own P38 - mostly around changing lots of things to being LED lit, and updating the navigation/radio systems - but the locking/immobilisation on these vehicles is definitely proprietary and a pain to put anything aftermarket in... I've had a couple of owners come to me with vehicles they've bought which have had aftermarket systems fitted for locking/immobiliser and one did have a push button start in it too, and they've all asked me to get rid of them and just make it work reliably again. If you can get it all to work, then congratulations! But also be aware of input/output lines to/from the BECM - I had one come my way from Canada where the owner had been working on fitting a remote start system, so in the winter he could start it from inside the house to get it warming up - but still keep it locked etc. It was a 2 part system that did remote locking and all that, aswell as remote starting - and it ended up frying a couple of components on the BECM logic board - which luckily I was able to trace/replace for him - but I think after that he binned the project as he didn't want to risk damaging the BECM again.
My 0.02 for you!
The microswitches in the drivers door, as you have found are:
Door Ajar Switch: Found in every door, and feeds an input into the BECM if the door is open/closed
Key Switch: Found only in the drivers door, this triggers whenever the key is turned from the central position in one direction or the other.
CDL (Central Door Locking) Switch: Found in both front doors, and will feed a locked/unlocked signal INTO the BECM to tell it if the door has been locked or unlocked. The BECM will then use this (to trigger the central locking for other doors). If triggered on it's own with the vehicle in an unlocked state, then it will just lock the doors and NOT set the alarm (eg if you are in the vehicle and lock the doors for personal security etc). If in the drivers door the BECM sees this switch change state ALONG WITH the key switch, it will assume that the vehicle has been locked/unlocked with the key in the door and arm/disarm the alarm/immobiliser accordingly.
For what you are trying to do, you will want the passive immobiliser (coil around the ignition) DISABLED as when it's enabled, it will automatically time out the immobiliser when the vehicle is unlocked, and this will then be reset when the fob is put back in the ignition - it is detected with the key in switch, the BECM pulses the coil, and the fob sends an unlock code to re-mobilise the vehicle, or you have to press the unlock button again to resend a valid code. If you are planning on doing away with the current fob, then you want the passive immobiliser disabled, as without a valid fob code being transmitted, the vehicle will stay immobilised and won't start. The aftermarket system won't be able to spoof that either.
You wouldn't need to leave the key in the ignition in the ACC position either, as it's plenty easy enough to bypass this to make it think that a) Ignition Pos I is on, and b) the key isn't in the ignition. The other problems you will have to overcome include...
- The P38 being a power hungry beast at the best of times. with ACC on (which is an input to the BECM, it then does a load of things with that information - it isn't just a simply relay output) other things are powered up under the bonnet and in the BECM, so you will have an additional power draw there, and the BECM is unlikely to go to sleep.
- If you make it so the key in ignition warning is disabled, then the BECM will permanently think the key is removed - which gets rid of the annoying warning, and will let the vehicle lock/alarm via input triggers to the drivers door - which is what it sounds like you are trying to do. The problem I can see with this is that it's probably going to throw up an "Engine Disabled" warning and not send the immobiliser code to the engine ECU to allow starting if it DOESN'T think the key is in the ignition. If it hasn't detected the key in the ignition, and you then try to go to position II or III to start, then it will probably think it's being stolen. I haven't tested to see if this is an actual problem before, but it's something to keep in mind.
- If you keep the key in ignition switch enabled, to make sure it starts and doesn't think it's being stolen, or keep the key in the ignition, then you will have the issue of the BECM not allowing the rest of the vehicle to be locked/alarmed, as it's a feature to help stop you from leaving your keys in the ignition and locking them in the vehicle.
A lot of the inputs it sounds like your remote system and push button starter need are possible to spoof, but they're all on the input side to the BECM, rather than the BECM sending out a 'locked/unlocked' signal to anything - as it's all handled internally.
I hope that helps explain a bit more of the P38 system to you - my advice, from someone who works a bit on BECMs and locking/immobilisation issues on P38s is in line with the others on here.... get the original system working as it should, as it is fairly robust - especially now most of the foibles of it are known and there are either fixes or upgrades now available from the aftermarket receivers to block RF interference - or the inline filter option that myself and another P38 owner make, or rebuilt door latches to make sure microswitches are working as they should.
I'm not saying that aftermarket projects aren't fun to work on - I've done a load to my own P38 - mostly around changing lots of things to being LED lit, and updating the navigation/radio systems - but the locking/immobilisation on these vehicles is definitely proprietary and a pain to put anything aftermarket in... I've had a couple of owners come to me with vehicles they've bought which have had aftermarket systems fitted for locking/immobiliser and one did have a push button start in it too, and they've all asked me to get rid of them and just make it work reliably again. If you can get it all to work, then congratulations! But also be aware of input/output lines to/from the BECM - I had one come my way from Canada where the owner had been working on fitting a remote start system, so in the winter he could start it from inside the house to get it warming up - but still keep it locked etc. It was a 2 part system that did remote locking and all that, aswell as remote starting - and it ended up frying a couple of components on the BECM logic board - which luckily I was able to trace/replace for him - but I think after that he binned the project as he didn't want to risk damaging the BECM again.
My 0.02 for you!
