Brake warning light, Light won't stop flashing with engine running Options

[jsaum]

The warning light on my 72 is staying on after the engine is started. I don't have a owners manual so I don't exactly know how the two red lights at the top of the fuel gauge normally operate. Months ago after I got the engine back in the car it went out the first couple of times I started the car. Now if flashes all of the time. I believe it will normally flash until the engine is started then will go out. I did reuild all of my calipers and installed a new 911 master cylinder. After bleeding the system repeated times I now have a some what firm pedal but it still seems like it's not quite right. I pulled the cover and checked the pressure switch and it is working the switch is made allowing a signal to pass through. I read some of the threads and there is mention of a reset button on the master cylinder but I don't think the 72 has it. I'm using the two lead switch. I also checked the e brake switch is is working correctly after I release the parking brake the fasten seat belt light will come on if the sealt belt isn't fastened. Has anyone had this problem before? What am I missing?

Thanks for the help!

Jsaum

[McMark]

Check for continuity between the two terminals or the one terminal and the body. You should be able to operate the switch by hand and you should be able to toggle between 0 ohms and infinity. Also look inside the MC where the switch mounts and make sure the plungers are centered.

[jsaum]

I checked the switch and am getting continuity through the switch it seems to be working properly.

Jsaum

[Tom_T]

Ummmm .... wait a minute folks & read his first post again, before you have him drag out ohm meters & tear the car apart.

The e-brake warning light is supposed to be on whenever the e-brake is engaged & when you start the car or turn the key to the run position, then it goes off when you release the e-brake fully. It is just that - a warning light to let you know if the e-brake is still on or fully released.

Sometimes on the early 914's with the 2 position "lock & drop" lever/handle, they will not fully engage the release switch to operate the warning light.

Don't know which you have, but first try releasing the e-brake with the engine running & see if it goes out.

Similar deal with the "Fasten Seat Belt Light" - try buckling the belt - then it goes out!

Simple!!!! ... no funny voices to tell you your seat belt is unbuckled or "a door is ajar" in these old gals! (IMG:style_emoticons/default/biggrin.gif) ... I mean - how can "a door" be "a Jar" anyway!!?? (IMG:style_emoticons/default/blink.gif) (IMG:style_emoticons/default/lol-2.gif)

The primitive warning sequence was set up in that order, presuming that you weren't driving off until you released the e-brake - rather than as soon as you start the engine as in modern cars - which is a pain if you want to get a map out or something with your belt off & the engine running! (IMG:style_emoticons/default/dry.gif)

[swl]

What Tom said (IMG:style_emoticons/default/smile.gif)

That cct is also a switch to ground so any sort of short in the switch or a pinched cable under the seat can leave the light flashing.

[jsaum]

I pulled the brake pressure switch and made sure it was working correctly it is! The seat belt switch is working along with the door switch! So I must have a short some where. I'll pull the seats out tomorrow and start chasing down the wiring . Oh what fun! I hate electrical issues.

[scrz914]

Okay, IF the light is flashing when the e-brake is released it might have to do with the connections at the master cylindar. Don't ask me why, but I had this same situation and my mechanic pulled one of the connections and said to tape it off and leave it that way. He said the MC I had was not stock and didn't need both connections. It works as expected now and I never really looked into it further. Just a thought.

[jsaum]

Thanks for the advice that's my next step. I see in the wiring diagram that the brown wire goes to ground and the brown /white wire goes up to the gauge. I'm going to pull the brown wire and see if it solves my problem and possibly install the single lead sensor. It looks like all that switch is doing is completing the circuit with the ground. There has to be a relay or a diode or something to make it flash then once the engine starts something will cause it to switch and stop. Hopefully I can just disconnect the one wire.

Jsaum

[underthetire]

Did you pull the Ebrake switch and make sure it's not your problem? The wire can chafe in the sheetmetal.

[blitZ]

It's possible the master cylinder was replaced with a version with a reset button. Easy to find out. Jack up the drivers side, position a jack stand. Loosen the two driver side boldt holding the pan covering the steering rack. Feel around for the reset button.

[jsaum]

I did pull the e brake switch and it seems to be working. I'm going to double check the wire again. With the e brake pulled the seat belt light is off. When I release the e brake the seat belt light will come on if I don't have my seat belt fastened. Once I fasten the seat belt the seat belt light goes off. So it seems like every thing is working correctly. I did replace the master cylinder with a 911 type have have the two connector type switch currently installed it is working correctly. I still haven't seen a picture of the infamous master cylinder reset switch! I have the front cover pulled so I can get at the master cylinder. In some of the threads it talks about the reset being part of the pressure switch. Anyone have a picture of the reset switch?

Jsaum