Blinking brake warning light

[rpc356]

I recently purchased a 73.5 (my first 911). In the process of sorting it out, I found the brake warning light had been pulled out of the back of the gauge and taped with electrician's tape. When I took the tape off, the light always blinks. Seems pretty clear what some PO did rather than actually fix this problem.

I've read the threads on this forum and have done the following. With the wires off the switch in the MC, the light goes out. I removed the switch from the MC and tested it with an ohm meter. Seemed to work fine (plunger out, no continuity; plunger in, continuity). Next I flushed the brake system. After a recent drive I checked the rotor temp with an IR thermometer and I got similar readings side to side, and slightly higher readings in the front than the back. The rubber brake lines are all dated 2008. The brakes seem to work fine, btw.

One oddity (at least to me). When used, the directional signal blinks in unison with the brake warning light.

Suggestions?

Thanks,
--Richard

[dporsche74]

the blinking light is normal with the e brake on . sometimes you have to push down on the ebrake handle to make it go off .
in your case might need a slight adjustment to the contact or a new switch ,

[rpc356]

the blinking light is normal with the e brake on . sometimes you have to push down on the ebrake handle to make it go off .
in your case might need a slight adjustment to the contact or a new switch ,

Yep, understood. Let me check my logic. At any given time either the ebrake switch or the brake warning switch (or both) could be closing the circuit and causing the light to blink. So, with the ebrake in the down position the light blinks. If pulling the wires off the MC stops the blinking, then that eliminates the ebrake switch as the culprit, right?

[HarryD]

Yep, understood. Let me check my logic. At any given time either the ebrake switch or the brake warning switch (or both) could be closing the circuit and causing the light to blink. So, with the ebrake in the down position the light blinks. If pulling the wires off the MC stops the blinking, then that eliminates the ebrake switch as the culprit, right?

I had the same issue on my 1973.5. I ran the same tests and got the same results. Turned out to be a bad switch on the MC. Stopped happening when I replaced it.

[rpc356]

I had the same issue on my 1973.5. I ran the same tests and got the same results. Turned out to be a bad switch on the MC. Stopped happening when I replaced it.

I tested the switch with a VOM and it appeared to function correctly. Was that your experience? I could perhaps believe that the switch is internally worn and requires a longer throw to break continuity, which would cause the light to be on all the time. However, the switch is a $100 part, so want to be reasonably sure that's what the problem is.

[edmayo]

Does everything work normally if you remove both wires from the M/C switch, and do you have a two pole switch at the M/C?

[rpc356]

Does everything work normally if you remove both wires from the M/C switch, and do you have a two pole switch at the M/C?

The switch is two pole. Let me verify tomorrow whether things work otherwise correctly when the wires are disconnected.

[HarryD]

I tested the switch with a VOM and it appeared to function correctly. Was that your experience? I could perhaps believe that the switch is internally worn and requires a longer throw to break continuity, which would cause the light to be on all the time. However, the switch is a $100 part, so want to be reasonably sure that's what the problem is.

I do not remember if mine worked correctly upon removal. However, if you go over to Pelican Parts (www.pelicanparts.com), it costs $39.50 (P/N 901-613-115-00-M14) not $100.

[rpc356]

I do not remember if mine worked correctly upon removal. However, if you go over to Pelican Parts (www.pelicanparts.com), it costs $39.50 (P/N 901-613-115-00-M14) not $100.

Thanks Harry, that's much better. The $100 price came from the Stoddard web site.

[Mr9146]

My brake warning light doesn't work with the handbrake like it should (although the buzzer does), but it loves to come on when the road gets bumpy.

It eventually goes away after I use the brakes a few times.