blindspot monitor buzzer addition

[DV52]

Thx for your detailed reply Don. I have been poring over the 1964 pages of wiring in the Golf manual pdf. I repeat 1964 pages.

I found pins 3 & 4 and now. here's how I understand the arrangement:
From J1087 unit 2, pin 3 goes to lamp K303 by way of a yellow wire to a 27-pin terminal TTVL for the front left door. Then that yellow goes to a 2-pin terminal TTIVL IN the front door, then a (red+green) wire goes to the LED in the mirror.


It looks to me that only J1087 does the leds but also goes to J1086 and thence to the CAN bus, thus using pins 3 & 4 avoids CAN bus involvement.
Only J1087 is for the LEDs but I can't see how J1086 "tells" J 1087 to light up K304 when it detects a vehicle.

I have removed the door “cards” and the trim covering the connectors inside the car and connecting in both places looks very awkward.
Could I use wires in the door sill harness which runs from the back of the car but before they reach the connectors?



In the passenger-side sill, I can only find a yellow that is twisted/paired with blue & there are no blues from J1087. Is that yellow the one I want?
Would the green wire I need for the driver-side be in the driver door sill?

Thanks

Yes, I believe that you have interpreted the wiring diagram correctly.

In terms of how the comms happens, whilst J1087 is indeed the module that drives the lamps (they are indicated as incandescent, not LED in the wiring diagram - yes, I was surprised too), it's J1086 that has full CAN status and it's this module that has direct participation in communications with the rest of the car's CAN network.

As you have observed, J1087 is connected to J1086 in what seems to be sub-CAN arrangement (so J1087 is a kind of "slave" to J1086). I assume that instructions like "light up K304" happens over this sub-CAN link between J1086 and J1087.

As for the best place to splice the connections, here's my cut-down version of the relevant information:



As you can see and as you have said - the BSM lamp wires travel along the bottom sills from the rear of the car (where J1087 is located) to the 27 x pin coupling points TTVR & TTVL. The wires then enter the door cavities at these coupling points. I agree that the car interior side of these coupling points is probably the best place to make your connections.

You should see a green wire connected to pin#1 on the right-side coupling point. This is the wire that connects to Input on the right-side transistor circuit and a brown wire on pin#2 connects to Earth in my transistor circuit

The left side connection points are the same for the yellow wire on pin#1 of the coupling point which connects to Input on the left-side transistor circuit. It depends on where you mount the new LEDs - but if it's convenient, you don't need to run another earth - just use the same brown wire connection from the right side.

If this was my project and before I reached for a blade to cut the wire insulation, I would borrow a small sewing needle from my current life-time partner (wife). Pierce the insulation on the yellow, or green wire so that the needle touches the copper wire, then using a multi-meter, check that a voltage (to an earth point) appears on the needle when the BSM lamp illuminates - both of the native BSM lamps turn-on as part of a test-cycle at ignition switch-on.

Again, before any permanent wiring changes are made and assuming the check above is OK, I would temporarily hook-up my prototype transistor circuit to the needle (and earth) and check the operation of the additional circuit- as proof-of-concept

Don

PS: I'm not sure about your mention of a "blue wire" on TTVL. I can't find any such colored wire on my wiring diagram - but if it's physically there on your car - it almost certainly isn't related to your project

[notaGolfR]

Yes, I believe that you have interpreted the wiring diagram correctly.

In terms of how the comms happens, whilst J1087 is indeed the module that drives the lamps (they are indicated as incandescent, not LED in the wiring diagram - yes, I was surprised too), it's J1086 that has full CAN status and it's this module that has direct participation in communications with the rest of the car's CAN network.

As you have observed, J1087 is connected to J1086 in what seems to be sub-CAN arrangement (so J1087 is a kind of "slave" to J1086). I assume that instructions like "light up K304" happens over this sub-CAN link between J1086 and J1087.

As for the best place to splice the connections, here's my cut-down version of the relevant information:



As you can see and as you have said - the BSM lamp wires travel along the bottom sills from the rear of the car (where J1087 is located) to the 27 x pin coupling points TTVR & TTVL. The wires then enter the door cavities at these coupling points. I agree that the car interior side of these coupling points is probably the best place to make your connections.

You should see a green wire connected to pin#1 on the right-side coupling point. This is the wire that connects to Input on the right-side transistor circuit and a brown wire on pin#2 connects to Earth in my transistor circuit

The left side connection points are the same for the yellow wire on pin#1 of the coupling point which connects to Input on the left-side transistor circuit. It depends on where you mount the new LEDs - but if it's convenient, you don't need to run another earth - just use the same brown wire connection from the right side.

If this was my project and before I reached for a blade to cut the wire insulation, I would borrow a small sewing needle from my current life-time partner (wife). Pierce the insulation on the yellow, or green wire so that the needle touches the copper wire, then using a multi-meter, check that a voltage (to an earth point) appears on the needle when the BSM lamp illuminates - both of the native BSM lamps turn-on as part of a test-cycle at ignition switch-on.

Again, before any permanent wiring changes are made and assuming the check above is OK, I would temporarily hook-up my prototype transistor circuit to the needle (and earth) and check the operation of the additional circuit- as proof-of-concept

Don

PS: I'm not sure about your mention of a "blue wire" on TTVL. I can't find any such colored wire on my wiring diagram - but if it's physically there on your car - it almost certainly isn't related to your project

Hi Don,
Long story short I had no luck.

I know I have the correct yellow as I see a voltage with the needle test. I cut the yellow and get ~ 9.7 V for a few seconds when I press the ignition. For 11.1 V you calculated R2 as 20 K ohms & I tried 20 K and then 10K for 9 V input.

I have quadruple checked connections, checked correctness of resistors in the circuit & confirmed correctness of transistor connections (don't know why they don't mark which is the Collector). What happens is that the LED lights very bright, but stays on, whereas the driver side comes on briefly as expected. I have the wire for power to the led connected to + on a blank plug I bought into the cigarette lighter socket then to the long leg of the led.

It's as if power to the led then R1 (resister + pot) is going thru the transistor to earth whenever the ignition is on and the signal from the yellow via R2 is doing nothing.

Any ideas?

When you say use 20 K oms for R2 instead of 20.2 "for reliability" can you explain please?

[DV52]

@notaGolfR: hmmm........ I just "bread-boarded" my design using an old 2N3094 that I found in the junk box and the resistor values in my calculations (and a bog, standard LED) - worked perfectly!!!

Clearly- if you want to persist, you need to resolve what's keeping the LED switched-on. Of course anything is possible and remote problem solving is fraught with difficulties. But, to my mind - two possibilities arise:

1. Without intending any offense, the circuit has been incorrectly wired (yes, I know that you "have quadruple checked connections, checked correctness of resistors in the circuit & confirmed correctness of transistor connections (don't know why they don't mark which is the Collector)" Incidentally, the 2N3094 from my junk box actually has the Base, Emitter, Collector leads marked on the housing!
2. The nature of the voltage that drives the native BSM light (on the mirrors) is not as I expected. My design assumes that the waveform of this trigger is a "square" pulse - meaning no-voltage (at all) when the BSM lamp is off and a positive voltage when the lamp is switched-on.

So- to confirm that option 1 (above) is not a problem , do this - Remove the Yellow wire from your device and connect the point that I have labelled Input in my diagram to earth. With this arrangement, the Transistor switch is "crow-barred" into the OFF state because the voltage to the Transistor Base is forced to zero - is the LED on your device off with Input earthed?

If the answer is NO (i.e. the LED is still turned-on) -clearly something is wrong with the construction, or the transistor is blown.

If the answer is YES - using a good multi-meter, check the voltage between the Yellow wire AND THE TRANSISTOR EMITTER pin with the native BSM lamp switched-off.

let me know your findings and we can think about the next steps

Don

When you say use 20 K oms for R2 instead of 20.2 "for reliability" can you explain please?

As you have probably observed, the design calculations for the Transistor Base resistor was very inexact - because it relied on a hfe value (remember this was the "DC current gain") that came from the specification sheet. I used hfe=60 which applied for a typical transistor collector-emitter current of 50 mA. Your circuit has a collector-emitter current closer to 30 mA depending on the position of the slider on the variable resistor.

Truth is that my choice of Base resistor was pretty-rough! However, the value of this resistor ain't that important because in a transistor switching circuit - all that is needed is sufficient base current to saturate the transistor (and the hfe value that I used was a guaranteed "minimum" value - so the actual hfe on a real world transistor will be higher anyway).

And in any event, your device clearly has full transistor saturation because the LED is illuminated (all the time)

Don

[notaGolfR]

There's no worries offending me by thinking I may have incorrectly wired the circuit. As I guess you have suspected I did get the C & E the wrong way round previously


I just re-read an earlier post of yourswhere you said to trial by connecting to the needle i.e. with the oe included. Maybe that'swhere I've been going wrong as I cut the yellow. It would be good to have both o.e. lamps and my mod asdrivers can tell by the oe's if they are in one's blindspot.

I measured V between yellow and collector with the oe off & I got 0.52 V. Then on the actual forum I noticed you said to the Emitter, so you must have edited. That was a trick . I get 0.58 V to the Emitter. That is by the needle in the yellow.


Out of interest I also measured with the yellow cut, and oe off,between yellow and collector I get 0.463 V and yellow to Emitter Iget 0.535 V

When testing I have been using a seat bolt as I haven't got around to tracking which brown out of several in the sill harness.

[DV52]

^^^ hmm.... not sure what you are telling me (have you found the problem?) - but those low voltage readings should not be sufficent to light-up the transistor LED when the native BSM lamp is not illuminated!

And just for clarity, I had assumed that it was understood that you need to construct 2 x identical new circuits; one for each side of the car!! Please re-read my previous post in which I identify a "left-side transistor circuit" AND a "right-side transistor circuit"

And, again as I said in my earlier posts, you should use the brown wire from the loom as the earth for both transistor circuits. Don't use a "bolt" or any another earth wire - because depending on how the modules are earthed, using a totally different earth point can generate earth loops from the noisy environment of a car (which can cause problems).

As for which brown wire to use - look at my wiring diagram. You can see that there is a brown wire on pin #2 which is immediately next-to the pin for the yellow wire on TTVL. Or you can use the brown wire on TTVR pin #2


Don

[notaGolfR]

^^^ hmm.... not sure what you are telling me (have you found the problem?) - but those low voltage readings should not be sufficent to light-up the transistor LED when the native BSM lamp is not illuminated!

And just for clarity, I had assumed that it was understood that you need to construct 2 x identical new circuits; one for each side of the car!! Please re-read my previous post in which I identify a "left-side transistor circuit" AND a "right-side transistor circuit"

And, again as I said in my earlier posts, you should use the brown wire from the loom as the earth for both transistor circuits. Don't use a "bolt" or any another earth wire - because depending on how the modules are earthed, using a totally different earth point can generate earth loops from the noisy environment of a car (which can cause problems).

As for which brown wire to use - look at my wiring diagram. You can see that there is a brown wire on pin #2 which is immediately next-to the pin for the yellow wire on TTVL. Or you can use the brown wire on TTVR pin #2


Don

Thx Don. No I haven't found the problem (yet). "not sure what you are telling me"... I was telling you the voltages you asked for betw. the yellow & Collector and yellow & Emitter, and yes, no LEDs light if the native BSM lamp is not illuminated!.

I certainly intend to make two circuits, i.e. one for left to yellow & right to green.

Locating the correct brown earth wire is difficult as I can't see where it goes out from the door to the connector. I have a crook neck and back that I'm not game to stir up. There are at least 4 browns in the sill loom so I'll try your needle tip to locate i.e. look for a voltage when I press the ign. button.

I know about earth-loop hums from my audio gear but didn't consider it in this case.

Please keep well

[notaGolfR]

Hi Don,
Thx for all your effort here. I'm a bit embarressed about it. Let's give it a rest as I don't seem to be getting anywhere. Our son is showing up from Melbourne in a couple of months & has some electronics knowledge & has breadboarded the circuit too. He got it working so is going to try to help when (who knows these days) he arrives.
Meanwhile I will keep losing sleep over it & looking at the manual for thoughts & trying things. I did in fact writhe about looking at the plethora of wires that go in & out of the front door & there's more than one brown. and so awkward for me to manipulate that I spat the dummy.

I have been documenting much of the experience with a view to posting a how-to-do, in a style that a 7-year-old could follow, as indeed you have done.

BTW, I asked the service department what the mystery blue wire around the yellow is & was told it is the keyless entry antenna. Why it is associated with the yellow was a red-herring and mystefies me. Another mystery is the manual's reference to "T27 27-pin connector black"where I can't see any such connector. The one I found where I expected it was white and less than 27 pins.

[DV52]

@notagolf: OK - Happy to discuss further (over mobile/FaceTime). PM your mobile if you want

Don

[notaGolfR]

@notagolf: OK - Happy to discuss further (over mobile/FaceTime). PM your mobile if you want

Don

Thanks for your kind offer to mobile/FaceTime. I will probably need to do that but I hate to bother people, so meanwhile I will try a few more things on my own, hopefully learning in the process.

Keep well and try not to worry about being a Victorian

[notaGolfR]

Hi Don. Our son from Melbourne is with me now with a high quality multimeter and his working-breadboard of your circuit and we checked a few things to no avail.

Today I tried having the yellow wire along the door sill cut and when pushing the ignition button to do the blindspot lamp test, the blind-spot lights and goos out as usual. Therefore, we think that despite the circuit diagram clearly showing the yellow as the target, we must have been fiddling with the wrong wire, or some circuitry or device further along, specific for the lamp controls it but we can't see anything on the diagram.

Any further thoughts before we contort ourselves to get at a more direct connection?