I had not realised that there is an actual roof indicator lamp on the Z3, within the instrument cluster as below.
So I wondered how I could make use of this.
How the roof works is as follows: (stay with me..... or just skip to the method)
The roof microswitch is switched 'normally open' when the roof is clamped shut. ie the circuit is not passing through it.
One connection on the microswitch goes to an earth point.
The other connection goes (eventually) to the roof buttons.
When you flip up the front part of the roof, the microswitch operates and the earth circuit is now made through to the roof buttons.
There are two relays mounted near the roof motor, one for up, and one for down.
A relay is a powered switch, so you can pass the big current required for the motor, without burning out the little switches in the console roof buttons.
The relays use a coil which when energised uses magnetism to close the bigger switch.
The coil only needs a small amount of current to energise it, hence this does not burn out the small roof switches.
When you press the roof 'down' button, the earth circuit is then sent to the coil of the 'down' relay.
If you press the 'up' button the earth is sent to the coil of the 'up' relay instead.
But to energise a relay coil, you also need a +12v, as well as an earth.
This is where the brake pedal comes in.
The brake pedal provides +12v to the brake lights. but that +12v also goes to the coils of both relays, regardless of whether you want to open or close the roof, and it happens every time you press the brake pedal.
This is why, to operate the roof, you need to both flip the roof, and press the brake pedal.
There is a larger +12v ignition supply that goes to the big switch on both relays, which ultimately powers the direction of the motor when the relevant coil energises and operates that big switch.
I have bored you enough, so I wont go into the workings behind how the relays swap the circuit between earth and +12v for the motor.
Anyway, investigation:
The lamp position is the 5th one from the right, when looking at the rear of the cluster.
First of all, I fitted a spare lamp, and then looked for the associated connection pins needed to light it.
The circuit track that runs along the very bottom edge of the circuit board, is energised +12v ignition controlled and is used for nearly all of the tell tales, with an earth completing the individual circuit for each lamp condition.
I did find one half of the circuit that if supplied with an earth it lights the lamp, this was on pin 23 on the Blue connector.
I want to find a circuit that would light the lamp on both of the open, and close movements.
The earth I can use is the one that comes originally via the microswitch.
It occurs either via the up or down button, and only happens if the relevant button is pressed with the roof pushed up.
But if I just put that on pin 23, it would light the lamp, even if I hadn't pressed the brake pedal. This is because the +12v is being supplied by the track on the bottom of the cluster circuit board.
I wanted a way of knowing the circuit from the brake pedal was also made.
If I could use that as the +12v, with the earth from the microswitch, and the lamp lit when I pressed either up or down button, then I would have an indication that proved the circuits of the usual troublesome parts of the roof operation were OK.
To do this I would need to break the circuit board track, and wire up the lamp direct.
Method:
Take a spare lamp:
cut away the black plastic just above the terminals so you can solder on a set of wires
Now I used a dremel to cut away both tracks on the board. (Ignore the lamp circuit to the right, that was the cruise control lamp trial)
Then fit the lamp: (again ignore the lamp circuit to the right, that is my cruise control lamp trial, and I swapped wire colours)
refit the cluster and run the wires though behind the dash to the footwell.
Next up, is to wire into the brake pedal switch.
On the brake pedal switch is a blue and red wire, this provides that +12v to the brake lights and relay coils.
Cut the wire,
join, solder and heatshrink any one of the two lamp wires to it.
The next is a bit tricky.
Remove the roof switch,
You will need to get to the brown & yellow wire (Up), and the brown & red wire (Down). these send the earth the relevant relay once that button is pressed.
Now these earths need to go to the second lamp wire,
However, if you connect them both to the lamp wire, you have no longer got separate up and down circuits anymore. so you need some electroniccy type bits..
These are diodes, they allow current through one way but not the other, and have a stripe around them to indicate where the flow goes.
I wont explain exactly how they separate the circuit, but this is the way they need to go:
Join the two ends furthest away from the stripes, these will go to the second lamp wire.
solder and heatshrink the lamp wire to the twisted diode wires.
For the other ends, one will go to the brown & red wire, so solder and heatshrink
and the other will go to the brown & yellow wire: solder (as shown) then heatshrink
The diodes keep the circuits separate provided they are fitted the right direction..
and that's it,
all done
try it, and then and refit the switch;
Now, if the roof wont go down, but the lamp lights, you can instantly see that the circuit is correct from the pedal, the microswitch and the buttons, and the problem is upstream of them.
If the lamp doesn't light there is a problem with one of these circuits.
Pointless? maybe, but I enjoyed the tinkering
.
So I wondered how I could make use of this.
How the roof works is as follows: (stay with me..... or just skip to the method)
The roof microswitch is switched 'normally open' when the roof is clamped shut. ie the circuit is not passing through it.
One connection on the microswitch goes to an earth point.
The other connection goes (eventually) to the roof buttons.
When you flip up the front part of the roof, the microswitch operates and the earth circuit is now made through to the roof buttons.
There are two relays mounted near the roof motor, one for up, and one for down.
A relay is a powered switch, so you can pass the big current required for the motor, without burning out the little switches in the console roof buttons.
The relays use a coil which when energised uses magnetism to close the bigger switch.
The coil only needs a small amount of current to energise it, hence this does not burn out the small roof switches.
When you press the roof 'down' button, the earth circuit is then sent to the coil of the 'down' relay.
If you press the 'up' button the earth is sent to the coil of the 'up' relay instead.
But to energise a relay coil, you also need a +12v, as well as an earth.
This is where the brake pedal comes in.
The brake pedal provides +12v to the brake lights. but that +12v also goes to the coils of both relays, regardless of whether you want to open or close the roof, and it happens every time you press the brake pedal.
This is why, to operate the roof, you need to both flip the roof, and press the brake pedal.
There is a larger +12v ignition supply that goes to the big switch on both relays, which ultimately powers the direction of the motor when the relevant coil energises and operates that big switch.
I have bored you enough, so I wont go into the workings behind how the relays swap the circuit between earth and +12v for the motor.
Anyway, investigation:
The lamp position is the 5th one from the right, when looking at the rear of the cluster.
First of all, I fitted a spare lamp, and then looked for the associated connection pins needed to light it.
The circuit track that runs along the very bottom edge of the circuit board, is energised +12v ignition controlled and is used for nearly all of the tell tales, with an earth completing the individual circuit for each lamp condition.
I did find one half of the circuit that if supplied with an earth it lights the lamp, this was on pin 23 on the Blue connector.
I want to find a circuit that would light the lamp on both of the open, and close movements.
The earth I can use is the one that comes originally via the microswitch.
It occurs either via the up or down button, and only happens if the relevant button is pressed with the roof pushed up.
But if I just put that on pin 23, it would light the lamp, even if I hadn't pressed the brake pedal. This is because the +12v is being supplied by the track on the bottom of the cluster circuit board.
I wanted a way of knowing the circuit from the brake pedal was also made.
If I could use that as the +12v, with the earth from the microswitch, and the lamp lit when I pressed either up or down button, then I would have an indication that proved the circuits of the usual troublesome parts of the roof operation were OK.
To do this I would need to break the circuit board track, and wire up the lamp direct.
Method:
Take a spare lamp:
cut away the black plastic just above the terminals so you can solder on a set of wires
Now I used a dremel to cut away both tracks on the board. (Ignore the lamp circuit to the right, that was the cruise control lamp trial)
Then fit the lamp: (again ignore the lamp circuit to the right, that is my cruise control lamp trial, and I swapped wire colours)
refit the cluster and run the wires though behind the dash to the footwell.
Next up, is to wire into the brake pedal switch.
On the brake pedal switch is a blue and red wire, this provides that +12v to the brake lights and relay coils.
Cut the wire,
join, solder and heatshrink any one of the two lamp wires to it.
The next is a bit tricky.
Remove the roof switch,
You will need to get to the brown & yellow wire (Up), and the brown & red wire (Down). these send the earth the relevant relay once that button is pressed.
Now these earths need to go to the second lamp wire,
However, if you connect them both to the lamp wire, you have no longer got separate up and down circuits anymore. so you need some electroniccy type bits..
These are diodes, they allow current through one way but not the other, and have a stripe around them to indicate where the flow goes.
I wont explain exactly how they separate the circuit, but this is the way they need to go:
Join the two ends furthest away from the stripes, these will go to the second lamp wire.
solder and heatshrink the lamp wire to the twisted diode wires.
For the other ends, one will go to the brown & red wire, so solder and heatshrink
and the other will go to the brown & yellow wire: solder (as shown) then heatshrink
The diodes keep the circuits separate provided they are fitted the right direction..
and that's it,
all done
try it, and then and refit the switch;
Now, if the roof wont go down, but the lamp lights, you can instantly see that the circuit is correct from the pedal, the microswitch and the buttons, and the problem is upstream of them.
If the lamp doesn't light there is a problem with one of these circuits.
Pointless? maybe, but I enjoyed the tinkering
.
Last edited:
