Warning brake light on - 1976 US model

[P91176]

Hi, hope to find some help in this forum.
I have a 1976 911 2,7 i got as a disassembled project. I am now putting it togeather again but are having a issue with the "brake" warning light to be on. When i pull the handbrake up, the same light will light brighter, to me this means the handbrake light is working.
What can cause the "brake" warning light to come on all the time?
I have replaced the master brake cylinder with a new without the 1 pole switch, I could not get the correct US master brake cylinder and have installed a euro, do I need to jump the cable to ground or similar?

[EC900]

Not sure about the Euro MC or its wiring - but the single switch MC has a Reset button/stem that would turn dash warning light off in the event the circuit tripped it, low fluid or malfunction.

The circuit controls both the dash warning light and handbrake function.
Brake warning will come on when the car is started and turns off after a few seconds.
It will also come on and stay on when the switch on the handbrake is out of adjustment. When handle is down the contact band is separated from the switch. It’s an odd design.

To determine if handbrake is out of adjustment…disconnect the wire under the handbrake assembly I think it’s Yellow. Dash light will turn off.
If staying on…then reconnect it and then pull wire/plug off MC pressure switch. Sometimes this will reset a switch malfunction and turn off dash lamp.
Adjusting the HB is slight it only moves a quarter inch or less so even a hair off it’ll make contact and turn on dash lamp. Some have tried to bend the bow and this can weaken it and eventually break.
When the Contact bow - that’s riveted to the handbrake handle - sometimes breaks off and remains lodged onto the switch therefore light is always On.

For Reference – Here’s the Reset button/stem on the brake
MC pressure switch. A cap rubber cap should be covering it.

[grant lyon]

The white nipple push button switch is on the (left/driver's) side of the 1976 MC that you need to press (reset) after you bleed the brakes. IIRC a central slug in MC is pushed to front or back of the MC as a result of a leak in the front/rear brake lines. An imbalance (movement of slug in cylinder from centered) happens if you bleed by pushing your brake pedal, and may or may not with pressure bleeder (IIRC with gravity bleed or with little/low pressure in bleeder tank you might not push the slug off-center). IIRC you can walk the slug back and forth by additional bleeding with less pressure to gently nudge the slug to center in addition to pushing the reset switch.

[30westrob]

I think you can reset the brake warning system by lifting the battery lead. If the fault is still present the light will come back on. Rob