Brake warning light, The quest for success continues Options

[PaIsa]

So I am back trying to get my brake warning light to work properly. The situation before I started searching for the solution was the following:

Brake warning light was always blinking whatever the car condition. Blinked with the ignition ON. Blinked with the engine running and hand brake applied (normal). Blinked with the engine running and hand brake removed. Blinked with the engine running, hand brake removed and MC wire disconnected. So basically, blinking all the time!

So I was investigating the emergency (hand) brake wiring. Remove the seats, center console, etc. Looked at the emergency brake switch and seemed to work OK. There was a contact (closed circuit) when the switch was in position where the emergency brake would be applied and no contact (open circuit) when the hand brake would be removed. Looked on the wiring for evidence of short to ground but was not able to find anything. The wire goes in the center tunnel and is accesible until the shifter where rather then following the main wiring harness and the speedo cable, it goes under and God knows where it goes!! So I was not able to follow it all the way.

Now I have some disconnected wires near the brake fluid reservoir (already a thread on this trying to understand where these should go). The wires are brown-white and brown-white connected with a brown wire. The brown-white wire that is connected with the brown wire is cut.

So after I reassemble the emergency brake wiring, I did some test again.

Ignition ON, the brake light comes ON. Whit the engine running, no more brake light blinking.

So now I tried with the cut wire (the one near the brake fluid reservoir) reconnected. Brake light blinking all the time. Disconnect the wires, no more blinking when the engine is running.

I am lost. Even writing this I am not sure if I am right with the tests I did and the results I got.

Anyone has any advice? I looked at the wiring diagram, but not sure!!

I would like to have this working but don't want to go crazy with this!!

The car is a 1972.

[Dave_Darling]

Have you checked the electrical switch in the side of the brake master cylinder? If you mentioned that, I missed it.

There's a switch in there that gets tripped if you lose brake pressure in the front or the rear brake circuit. (Say, if you boil your brakes, or have a brake line failure. Or if you just bleed the brakes.) It should have a reset button covered by a rubber nipple. Press the button to reset the switch.

Some switches do not have the reset button (they may be from a different model of car?) but those should reset by themselves when the pressure imbalance goes away.

A brown and a brown/white wire should go to the switch. The switch will short those together when it detects an imbalance. (Or rather, when a piston between the circuits gets moved by them having a large pressure imbalance.) Some switches only have a single wire connector; those ground through their threads. So the brown/white wire would be hooked up to them, and the brown wire taped up somewhere out of the way.

This switch, or the wiring to it, could also be the source of the brake warning light being on.

--DD

[PaIsa]

Have you checked the electrical switch in the side of the brake master cylinder? If you mentioned that, I missed it.

There's a switch in there that gets tripped if you lose brake pressure in the front or the rear brake circuit. (Say, if you boil your brakes, or have a brake line failure. Or if you just bleed the brakes.) It should have a reset button covered by a rubber nipple. Press the button to reset the switch.

Some switches do not have the reset button (they may be from a different model of car?) but those should reset by themselves when the pressure imbalance goes away.

A brown and a brown/white wire should go to the switch. The switch will short those together when it detects an imbalance. (Or rather, when a piston between the circuits gets moved by them having a large pressure imbalance.) Some switches only have a single wire connector; those ground through their threads. So the brown/white wire would be hooked up to them, and the brown wire taped up somewhere out of the way.

This switch, or the wiring to it, could also be the source of the brake warning light being on.

--DD

Yes I know of that switch. I have the 2 poles switch and it does not have a reset. I did some test with this switch disconnected and making sure that the 2 wires going to it were not grounding and still the brake warning light was flashing so my understanding is that this is not this switch that is the cause for the brake light flashing.

As I said, I will put this troubleshooting to rest for now and look at it deeper during the winter in a more detailed approach looking at each wires and understanding were they are going and better understand the circuit.