Wiring Diagram Question

[Captain_Keram]

Good Evening, 

So I am using this diagram which is for the BMW 1600-2 USA (12 Volt) and there is this one wire highlighted in light blue that I believe goes to my brake telltale light. I am wondering what the 2 things I circled in black are and where on the car I could find them?

 

Thank you,

Sam K.

1968 BMW 1600-2 "Ellie"

[bergie33]

The one on the right looks to be just a connection point. These are usually a rectangular clearish plastic insulator concealing the connection of a male and female spade connector.  It is probably under the dash. 

 

The one on the left looks like it it the connections on top of the brake fluid reservoir cap. 

[M3M3]

the one on the right is a connector.

 

the ones in the left circle are the switches on the handbrake and brake fluid res cap.

[John76]

Here's a sketch of the brake light circuit on the later cars.... may be similar to your '68 1600 12V car.

 

 

 

[tahoedon]

My 68 1600-2 does not have a switch on the reservoir or parking brake.  Those are the switches that turn on if there is unequal pressure in the tandem master cylinder which then turns on the small red light on the instrument cluster.  They screw into a fitting which is plumbed after the tandem master cylinder.  The brake light switch is also screwed into this fitting.  The wiring diagram  I have is slightly different than the one you show. This was in the owners guide supplement for the US version.

[Captain_Keram]

On 11/29/2022 at 8:05 PM, tahoedon said:

My 68 1600-2 does not have a switch on the reservoir or parking brake.  Those are the switches that turn on if there is unequal pressure in the tandem master cylinder which then turns on the small red light on the instrument cluster.  They screw into a fitting which is plumbed after the tandem master cylinder.  The brake light switch is also screwed into this fitting.  The wiring diagram  I have is slightly different than the one you show. This was in the owners guide supplement for the US version.

I think I know what you're talking about. The fitting is mounted to the inner fender below the resuvouir and booster. I am courious as to where I can get a new pressure switch for the car or at least what it looks like so I can find one. As I think mine has failed as the red light at my intrument cluster will not turn off. 

Thanks Sam

[John76]

27 minutes ago, Captain_Keram said:

the red light at my intrument cluster will not turn off. 

Sam,

Just unplug the Brown/blue wire (or whatever the color is other than brown) from the pressure switch.

You might be able to clean the switch to un-stick the internal ground contact.

That dash light is always "hot" (+12V) and only illuminates when something is grounded e.g., brake fluid level switch, brake pressure switch, hand brake switch, etc.  BTW, did you check the hand brake switch? This would be much easier and cheaper to fix if it is causing the red dash light to stay on.  Do you have a "test" button above the red Brake light on your dash?  This might also be stuck in the closed (grounded) position.

John

 

[Captain_Keram]

4 hours ago, John76 said:

Sam,

Just unplug the Brown/blue wire (or whatever the color is other than brown) from the pressure switch.

You might be able to clean the switch to un-stick the internal ground contact.

That dash light is always "hot" (+12V) and only illuminates when something is grounded e.g., brake fluid level switch, brake pressure switch, hand brake switch, etc.  BTW, did you check the hand brake switch? This would be much easier and cheaper to fix if it is causing the red dash light to stay on.  Do you have a "test" button above the red Brake light on your dash?  This might also be stuck in the closed (grounded) position.

John

 

Thank you and yes I have the little test button. How would one go about getting it unstuck? As I’m gonna check that tomorrow as well. 
 

Sam

[John76]

1 hour ago, Captain_Keram said:

How would one go about getting it unstuck?

I've never seen one, but I understand when you push it (ignition "on") it lights up if the system is good.

Might be the Brake light that comes on with a manual choke (if installed).

Good luck!

[Captain_Keram]

9 hours ago, John76 said:

I've never seen one, but I understand when you push it (ignition "on") it lights up if the system is good.

Might be the Brake light that comes on with a manual choke (if installed).

Good luck!

So I have cleaned the contacts and tested the button, which works. Yet the light still hasn’t turned off. I check and I don’t have a hand brake switch either. Here is a photo of the connections. I am wondering if something could be hooked up wrong

[John76]

Try switching the wires to see if it makes a difference.

 

[John76]

Some other places to check. Any Brown/blue wire that is grounded will turn on the Brake Light.

 

 

[Captain_Keram]

On 5/11/2023 at 2:47 PM, John76 said:

Some other places to check. Any Brown/blue wire that is grounded will turn on the Brake Light.

 

 

so I unplugged the wire at the sensor/switch and the light shut off. So Im certain its the sensor/switch as I noticed the 4 wires on the side of the "T" as I call it as both for brake light switches and the pressure switch is a single wire at the bottom of the "T". So I apparently have 2 brake light switches on this car. I have a part number for replacement for the controller switch as its called in my BMW Parts manual, but I cant find a replacement anywhere. I am also wondering is there a way to fix the sensor/switch or should I just try to replace it if possible. Part number is 61 31 1 350 350 

 

thank you,

Sam 

Edited May 21, 2023 by Captain_Keram
forgot some details

[tahoedon]

What you are calling the pressure switch is almost certainly a switch which has a plunger that completes the circuit when there is an imbalance between the two brake circuits.  When there is an imbalance the slide inside the fitting moves to one side and pushes down the plunger.  Try to remove the fitting and see if the plunger works.  I also seem to remember that years ago the slide on my 1600 got stuck to one side so the red light was always on.  I think that there is a plug on one side of this fitting that can be removed so that the inside can be cleaned out and the slide recentered which should turn off the red light.  I removed all the 1600 stuff years ago.  If I can find the plunger, you can have it, but I seem to remember giving it away years ago.  Wish I could draw like John76.

[Captain_Keram]

3 minutes ago, tahoedon said:

What you are calling the pressure switch is almost certainly a switch which has a plunger that completes the circuit when there is an imbalance between the two brake circuits.  When there is an imbalance the slide inside the fitting moves to one side and pushes down the plunger.  Try to remove the fitting and see if the plunger works.  I also seem to remember that years ago the slide on my 1600 got stuck to one side so the red light was always on.  I think that there is a plug on one side of this fitting that can be removed so that the inside can be cleaned out and the slide recentered which should turn off the red light.  I removed all the 1600 stuff years ago.  If I can find the plunger, you can have it, but I seem to remember giving it away years ago.  Wish I could draw like John76.

Ok thank you. Ill try taking it out and cleaning it up

 

Sam