An E28 wiring question.

I'm sending an alarm unit to my brother who lives some way away - and all
he needs it for is to provide remote lock and unlock for his '87 520 which
doesn't have it.

I'd like to give him chapter and verse on the connections and set the
alarm up correctly. But I don't have a wiring diagram for an E28 - but do
for an E34.

My idea is to fit the unit in the boot. And connect to the boot key
switch which operates the central locking. According to my E34 diagram the
key switch grounds either of the control wires which are coloured
green/black (lock) yellow/black unlock.

And take the power for the unit from the boot light feed.

Any gotchas I've missed?

--
*A backward poet writes inverse.*

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) > wrote:
>I'm sending an alarm unit to my brother who lives some way away - and all
>he needs it for is to provide remote lock and unlock for his '87 520 which
>doesn't have it.
>
> I'd like to give him chapter and verse on the connections and set the
>alarm up correctly. But I don't have a wiring diagram for an E28 - but do
>for an E34.
>
> My idea is to fit the unit in the boot. And connect to the boot key
>switch which operates the central locking. According to my E34 diagram the
>key switch grounds either of the control wires which are coloured
>green/black (lock) yellow/black unlock.
>
>And take the power for the unit from the boot light feed.

The green/black and yellow/black are the wires from the central locking control
unit to the trunk locking motor switch. I do think grounding them will
activate the lock properly.

>Any gotchas I've missed?

The fact that remote control locks are adding additional crap that can go
wrong, and the idea is silly anyway. Just put the key in the lock and
turn it, all right? It's not hard. Sheesh.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"Dave Plowman (News)" > wrote in message
...
> I'm sending an alarm unit to my brother who lives some way away - and all
> he needs it for is to provide remote lock and unlock for his '87 520 which
> doesn't have it.
>
> I'd like to give him chapter and verse on the connections and set the
> alarm up correctly. But I don't have a wiring diagram for an E28 - but do
> for an E34.
>
> My idea is to fit the unit in the boot. And connect to the boot key
> switch which operates the central locking. According to my E34 diagram the
> key switch grounds either of the control wires which are coloured
> green/black (lock) yellow/black unlock.
>
> And take the power for the unit from the boot light feed.
>
> Any gotchas I've missed?
>

I'm not sure that you want to ground those wires. My guess is that they
reverse polarity to make the lock go in the opposite direction. The locks
have a switch on them that tell the central locking system to lock or
unlock -- two switches, actually. But the wires leading to the lock solenoid
are going to be the power that tells the solenoid to push or pull the
plunger, they are going to be +12 and GND or GND and +12, depending on which
way the solenoid is supposed to go. Since the solenoid is DC, then reversing
the polarity will change the direction of the plunger. The wires going to
the lock switches might be grounded to tell the locking system what the key
is doing.

"Jeff Strickland" > wrote in message
...
>
> "Dave Plowman (News)" > wrote in message
> ...
>> I'm sending an alarm unit to my brother who lives some way away - and all
>> he needs it for is to provide remote lock and unlock for his '87 520
>> which
>> doesn't have it.
>>
>> I'd like to give him chapter and verse on the connections and set the
>> alarm up correctly. But I don't have a wiring diagram for an E28 - but do
>> for an E34.
>>
>> My idea is to fit the unit in the boot. And connect to the boot key
>> switch which operates the central locking. According to my E34 diagram
>> the
>> key switch grounds either of the control wires which are coloured
>> green/black (lock) yellow/black unlock.
>>
>> And take the power for the unit from the boot light feed.
>>
>> Any gotchas I've missed?
>>
>
> I'm not sure that you want to ground those wires. My guess is that they
> reverse polarity to make the lock go in the opposite direction. The locks
> have a switch on them that tell the central locking system to lock or
> unlock -- two switches, actually. But the wires leading to the lock
> solenoid are going to be the power that tells the solenoid to push or pull
> the plunger, they are going to be +12 and GND or GND and +12, depending on
> which way the solenoid is supposed to go. Since the solenoid is DC, then
> reversing the polarity will change the direction of the plunger. The wires
> going to the lock switches might be grounded to tell the locking system
> what the key is doing.
>
>

Having said all of that, does the locking thingy act like the key OR does it
actually power the lock solenoid(s), and if so, does it have enough power to
operate all of them?

If you splice this device into the system, then press a button to activate
it, whatever the device does to the lock solenoids, it will also do to the
existing Central Locking System, and any activation of the Central Locking
System is going to send the same signal to the newly installed device.

I don't know much but I know this stuff works by magic smoke, and I have the
uncomfortable feeling that you're about to let the magic smoke escape. If
you do it right, the smoke will escape from the Central Locking System and
the newly installed device all at the same time ...

This should be a sight, do you intend to sell tickets?

In article >,
Scott Dorsey > wrote:
> The green/black and yellow/black are the wires from the central locking
> control unit to the trunk locking motor switch. I do think grounding
> them will activate the lock properly.

Thanks.

> >Any gotchas I've missed?

> The fact that remote control locks are adding additional crap that can go
> wrong, and the idea is silly anyway. Just put the key in the lock and
> turn it, all right? It's not hard. Sheesh.

;-) Do you have a lever on the steering column to advance/retard the
ignition too?

--
*Why is the man who invests all your money called a broker? *

Dave Plowman London SW
To e-mail, change noise into sound.

In article >,
Jeff Strickland > wrote:
> I'm not sure that you want to ground those wires. My guess is that they
> reverse polarity to make the lock go in the opposite direction. The
> locks have a switch on them that tell the central locking system to
> lock or unlock -- two switches, actually. But the wires leading to the
> lock solenoid are going to be the power that tells the solenoid to push
> or pull the plunger, they are going to be +12 and GND or GND and +12,
> depending on which way the solenoid is supposed to go. Since the
> solenoid is DC, then reversing the polarity will change the direction
> of the plunger. The wires going to the lock switches might be grounded
> to tell the locking system what the key is doing.

For a start they're not solenoids but motors - if the same as my E34.
Dunno any central locking system that uses solenoids. They're not as
efficient as a motor.
On the E34, the boot switch does send a ground signal to either of the
control wires for as long as the key is held in that position. And a
control unit converts this into the pulse needed to operate the system.

The alarm unit (same as most aftermarket ones) has two changeover relays
operated by the remote which can be configured any way you want - and also
pulse for a time again set by the alarm. They can be used to operate the
motors directly in other systems since they are 20 amp relays. But in this
case it makes more sense to pulse the control circuits, since they are
easily accessible.

--
*Black holes are where God divided by zero *

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" > wrote in message
...
> In article >,
> Jeff Strickland > wrote:
>> I'm not sure that you want to ground those wires. My guess is that they
>> reverse polarity to make the lock go in the opposite direction. The
>> locks have a switch on them that tell the central locking system to
>> lock or unlock -- two switches, actually. But the wires leading to the
>> lock solenoid are going to be the power that tells the solenoid to push
>> or pull the plunger, they are going to be +12 and GND or GND and +12,
>> depending on which way the solenoid is supposed to go. Since the
>> solenoid is DC, then reversing the polarity will change the direction
>> of the plunger. The wires going to the lock switches might be grounded
>> to tell the locking system what the key is doing.
>
> For a start they're not solenoids but motors - if the same as my E34.
> Dunno any central locking system that uses solenoids. They're not as
> efficient as a motor.


Fine, they're motors. They still reverse directiion when the polarity is
switched.



> On the E34, the boot switch does send a ground signal to either of the
> control wires for as long as the key is held in that position. And a
> control unit converts this into the pulse needed to operate the system.
>
> The alarm unit (same as most aftermarket ones) has two changeover relays
> operated by the remote which can be configured any way you want - and also
> pulse for a time again set by the alarm. They can be used to operate the
> motors directly in other systems since they are 20 amp relays. But in this
> case it makes more sense to pulse the control circuits, since they are
> easily accessible.
>
> --
> *Black holes are where God divided by zero *
>
> Dave Plowman London SW
> To e-mail, change noise into sound.

In article >,
Jeff Strickland > wrote:
> > I'm not sure that you want to ground those wires. My guess is that
> > they reverse polarity to make the lock go in the opposite direction.
> > The locks have a switch on them that tell the central locking system
> > to lock or unlock -- two switches, actually. But the wires leading to
> > the lock solenoid are going to be the power that tells the solenoid
> > to push or pull the plunger, they are going to be +12 and GND or GND
> > and +12, depending on which way the solenoid is supposed to go. Since
> > the solenoid is DC, then reversing the polarity will change the
> > direction of the plunger. The wires going to the lock switches might
> > be grounded to tell the locking system what the key is doing.
> >
> >

> Having said all of that, does the locking thingy act like the key OR
> does it actually power the lock solenoid(s), and if so, does it have
> enough power to operate all of them?

It can do it any way you like. The relays are 20 amp so capable of driving
the motors directly. But my intention is to use the switch circuits.

> If you splice this device into the system, then press a button to
> activate it, whatever the device does to the lock solenoids, it will
> also do to the existing Central Locking System, and any activation of
> the Central Locking System is going to send the same signal to the
> newly installed device.

Hence using the switch circuits. When you turn the key you ground one of
the switch circuits. One for lock, one for unlock, depending on which way
you turn the key. This device sends a negative pulse to either of the
switch lines - so effectively duplicating the action of the switch.

> I don't know much

I'd say you're right there. ;-)

> but I know this stuff works by magic smoke, and I have
> the uncomfortable feeling that you're about to let the magic smoke
> escape.

Perhaps you need to learn how to read a wiring diagram. That's what my
question was about - as I don't have one for an E28. Luckily Mr Dorsey has
and understood the question. ;-)

> If you do it right, the smoke will escape from the Central
> Locking System and the newly installed device all at the same time ...

That's what fuses are for. ;-)

> This should be a sight, do you intend to sell tickets?

If I were anywhere near the car I'd not be asking as I'd have worked
things out myself. However, it's over 500 miles away and I want to give my
brother simple instructions on how to do it.

--
*Why do overlook and oversee mean opposite things?

Dave Plowman London SW
To e-mail, change noise into sound.

In article >,
Jeff Strickland > wrote:
> > For a start they're not solenoids but motors - if the same as my E34.
> > Dunno any central locking system that uses solenoids. They're not as
> > efficient as a motor.


> Fine, they're motors. They still reverse directiion when the polarity is
> switched.

Might just help others reading this to know what they're dealing with.

--
*Why is it considered necessary to screw down the lid of a coffin?

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" > wrote in message
...
> I'm sending an alarm unit to my brother who lives some way away - and all
> he needs it for is to provide remote lock and unlock for his '87 520 which
> doesn't have it.

I can just about understand the remote unlock (if you have salvaged it for
nothing from another car being scrapped), but an alarm for a 22 year old car
worth little more than its scrap value unless it is in absolutely concours
condition...

In the UK, even by 1996 the car had fallen to around 10% of its new price
and about 5% of the cost of a current direct replacement by then the two
generations on E39.

>
> I'd like to give him chapter and verse on the connections and set the
> alarm up correctly. But I don't have a wiring diagram for an E28 - but do
> for an E34.
>
> My idea is to fit the unit in the boot. And connect to the boot key
> switch which operates the central locking. According to my E34 diagram the
> key switch grounds either of the control wires which are coloured
> green/black (lock) yellow/black unlock.
>
> And take the power for the unit from the boot light feed.
>
> Any gotchas I've missed?
>
> --
> *A backward poet writes inverse.*
>
> Dave Plowman London SW
> To e-mail, change noise into sound.