Brake lights on all the time

[bob hughes]

FWIW I would buy your replacement switch but leave the old one in place until it goes again. I have two which I alternate when such troubles occur. Which is around every 3 years, I don't know why it goes wrong but that's a Healey for you.



Bob

 

[RAC68]

Hi Wana,

How confident are you that fluid pressure was released at the MC when the brake lights were stuck on. This is a more obscure possibility but the switch would remain activated if pressure in the brake lines is sufficient. I raise this thought as you indicated it took only a slight amount of peddle pressure to reactivate the brake lights after disconnecting and reconnecting electrical connections to the switch.

I had the pressure switch problem many years ago and installed an mechanical brake switch activated by the peddle arm that I wired in parallel with the pressure switch. Since I do use Silicone Brake Fluid Dot 5, my issue could have been caused by the fluid used. My experience, and that posted by others, seems to indicate the pressure switch fails "OFF" and will not respond to activating the brake lights. Your issue in having the light switch not deactivating the circuit (not turning Off the brake lights) seems counter to my understanding and expectation of how this switch would fail. My parallel wiring would assure proper brake light response if the pressure switch fails "OFF" (not closing the circuit) but will do nothing to help if the pressure fails "ON" (is stuck in the closed position).

Commonly, as I understand, the switch would take increasing amounts of peddle pressure to light the brake lights. This fact is often missed as the driver almost never is aware of this happening as there is no feedback on the dash that would show brake, or even turn signal, actual response. We are normally informed of the loss of the brake light by words passed by following drivers or a chance reflection on the garage door or from a passing store window. So, although I would question the performance of the switch, since all is preforming properly after braking the circuit connection, I would look further into the circuit to identify other possible sources of power reaching the brake lights along with verifying that brake fluid pressure is actually being sufficiently released.

My thoughts,
Ray(64BJ8P1)

 

[Bob_Spidell]

Hmmm .. I've not seen terminals like that before, and is the connector shown included, and does it fit the terminals?. IIRC, the garden variety switch has spade lug terminals; how do these fit? And--dumb question, but I gotta ask--are the threads correct for our cars?

 

[Wana]

Hi Wana,

How confident are you that fluid pressure was released at the MC when the brake lights were stuck on. This is a more obscure possibility but the switch would remain activated if pressure in the brake lines is sufficient. I raise this thought as you indicated it took only a slight amount of peddle pressure to reactivate the brake lights after disconnecting and reconnecting electrical connections to the switch.

Ray, you're asking an excellent question. The answer is; I'm not at all confident. I do know, however, that the brakes were not on while the brake lights were on all the time. Wouldn't they be on if the pressure in the system wasn't being released? I'm no expert mechanic by any means, so I have no idea if this would be correct.

 

[dklawson]

First test the switch as mentioned earlier. Disconnect both wires at the switch. If the brake lights go out, the problem is in the switch.

Don't fret about the connections. If the switch has the wrong terminals... make adapters. If you need bullet connectors or spade terminals, both are available at Britishwiring.com Buy the terminals you need and make adapter wire/pigtails by connecting the different terminals with short pieces of 16 AWG wire.

 

[RDKeysor]

That's a typical Healey repair. Disassemble the suspect organ, examine for a fault, reassemble, it works. My Lucas driving lights installed by a previous owner quit working. I found a bundle of wires wrapped in electrical tape and couldn't identify a problem. Rewrapped the bundle and the lights work. I also did an electrical brake switch of the type discussed here on a Jag, and it worked perfectly. The nice thing is if that component fails you simply switch the wires back to the hydraulic switch (this assumes that your hydraulic switche's failure hadn't caused you to convert to an electrical bit). The buyer of my MK2 Jag told me that he had retained the switch even though it was hung off the steering column in that car. You can adjust these switches to get the brake lights to come on with the slightest foot pressure or allow a bit more pedal depression before they work.

 

[Bob_Spidell]

...

Don't fret about the connections. If the switch has the wrong terminals... make adapters. If you need bullet connectors or spade terminals, both are available at Britishwiring.com Buy the terminals you need and make adapter wire/pigtails by connecting the different terminals with short pieces of 16 AWG wire.

Well of course. But I've not seen terminals like that, and I'm not gonna bodge such an important circuit (any circuit, for that matter). Anyone have a photo of a clean install using this switch? And what is the connector shown? Does it come with the switch?

 

[dklawson]

Are you talking about the male bullet connectors shown in Paul's pictures (page 1 of this thread)? If so, they are different than Lucas bullets but still available at many places. See the Amazon link below for examples. They were also used a lot on Ford vehicles from the 1970s.

https://www.amazon.com/Connectors-S...UTF8&qid=1537979240&sr=8-2&keywords=Sopoby214

If you don't want the switch that Paul used, there are other options. The common Lucas brake light switch in plastic with male spade terminals is available from BP Northwest for a very low price. See the parts below on their website.
Intermotor Brake Switch Part number: 51590
1/2-20 Jam Nut to Mount Switch Part number: FNZ206

If you want a more reliable and easily adjustable brake switch, use one from a 1970 BMW 2002. They are available from RockAuto. If you get the Airtex switch (RockAuto #1S5570) it comes with the jam nuts. It's largely metal and very robust. It also uses male spade lugs.

Regardless, you will have to fabricate something to mount the switch.

FWIW, when I installed the mechanical switch on the Mini I bought the correct color coded wires from Britishwiring.com I put the correct terminals on the switch end, ran those wires through the firewall and down to the hydraulic brake light switch. Then I put the correct terminals on the ends of the new wires, disconnected the the existing wires from the hydraulic switch and plugged my new wires into the existing ones. I made no cuts to the harness so everything could be put back to original if a future owner desired.

Nothing about this has to be a bodge.

 

[Keoke]

As a footnote to this discussion, hydraulic brake light switches often fail when used with DOT-5 brake fluid. Some advocate the use of the Harley-Davidson hydraulic switch as a better, functionally equivalent switch for use with DOT-5. When I experienced this failure on my Mini I chose a path similar to what Paul suggested above. I added a mechanical switch to the pedal box and left the failed hydraulic switch in place.

Yeah: That seems to be the simplest approach to this problem DK

 

[Lin]

Hello Bob,
I think there is some confusion about your "connector" question. Is your question about the Ron Francis Wiring Hydraulic Brake switch I referenced, or are you talking about the manual switch Paul referenced? If you are asking about the Ron Francis Wiring switch, I have attached a photo (it is a poor photo but the best I could come up with) of the switch installed on my Jag MK2 project. The switch is shown installed and is in the red oval ring. The connector comes with the switch and it slides over the two post terminals on the switch. Very easy to install. The wiring pigtail is just connected to the wires from your harness that went to the original switch. I just used bullet connectors and tubber sleeves supplied by British Wiring. I want to be clear: I am using the mechanical switch Paul referenced in his post on my Healey. The second image is of the mechanical switch installed in my Healey. The Ron Francis Wiring hydraulic switch is on the Jaguar. The Ron Francis Switch did activate the brake lights immediately - no visible delay at all.

 

[Lin]

If someone can give me a quick tutorial on how to post larger images, rather than the thumbnails, I would be happy to post the larger pix.
Lin

 

[Bob_Spidell]

Hello Bob,
I think there is some confusion about your "connector" question. Is your question about the Ron Francis Wiring Hydraulic Brake switch I referenced, or are you talking about the manual switch Paul referenced? If you are asking about the Ron Francis Wiring switch, I have attached a photo (it is a poor photo but the best I could come up with) of the switch installed on my Jag MK2 project. The switch is shown installed and is in the red oval ring. The connector comes with the switch and it slides over the two post terminals on the switch. Very easy to install. The wiring pigtail is just connected to the wires from your harness that went to the original switch. I just used bullet connectors and tubber sleeves supplied by British Wiring. I want to be clear: I am using the mechanical switch Paul referenced in his post on my Healey. The second image is of the mechanical switch installed in my Healey. The Ron Francis Wiring hydraulic switch is on the Jaguar. The Ron Francis Switch did activate the brake lights immediately - no visible delay at all.
Lin

Yes, I was talking about the Ron Francis switch (thanks for the reply). That seems like the cleanest install to me (and the silicone compatibility and low pressure activation are appealing). You answered my question; the connector shown on the website snaps onto the terminals on the switch with some leads for existing wiring. Still wonder why such oddball terminals are used on the switch; maybe that's a contemporary standard?

One more question: the leads on the Francis page are orange and purple, and yours appear to be green; did the connector come that way, or did you change them? And, can anyone verify the threads on Healey are eighth-inch pipe (okay, two more questions)?

 

[Lin]

I changed the wires to get a colors I desired. Same pipe fitting.
Lin

 

[Bob_Spidell]

Thanks, Lin.

 

[RAC68]

Lin,

Edit your post and do a double click on the picture and select the size you would like,


Wana,

I appreciate the issue is getting confusing and your simplest approach would be to just change the switch. However, finding the real cause of the problem is something I would continue to pursue until identified. To answer your question about residual brake hydraulic pressure without having the brakes solidly on, residual brake line pressure not sufficient to lock your brakes could remain in the system should something block its return through the MC. Although not sufficient to apply the brakes, it could be sufficient to trigger the brake switch at the low point of its required pressure range.

You mentioned resetting the switch/circuit by disconnected and then reconnected the electrical connections and, I assumed, pumped the brake peddle to validate it was now working properly. However, you stated the brake lights are now working but required less peddle pressure/travel (then prior) to activate the brake lights. This gives me pause as either the switch function has been altered and now requires less pressure to activate or there is a level of residual fluid pressure in the system and now requires a smaller amount of additional pressure to trigger your switch.

To test the switch, I would disconnect the Green/Purple line and either attach a multimeter or light bulb to that switch contact to check how the switch reacts when the peddle is pushed. Observing proper operation would lower the probability that the switch is defective. If you experience switch hesitation or delay, I would consider the switch as trash. Next, raise the car and spin a front wheel. If you note any resistance or brake drag, it is probable you have some residual pressure in the brake line. Since these are only preliminary tests, they would give you some follow-on direction.

Since this cold be no more than a transient occurrence, I would enjoy my Healey until a second instance of the problem is experienced.

Good luck and be careful,
Ray(64BJ8P1)

 

[Lin]

Ray,
I don't mean to redirect this thread, but I tried what I think you said and didn't seem to do anything. I am using a Mac if that makes a difference.
Lin

 

[John Turney]

Googled Ron Francis Wiring...
https://www.ronfrancis.com/prodinfo.asp?number=SW-32

PS - silicone compatible

Note their warning that they are not compatible with halogen bulbs due to a current limit of 4 amps.

 

[Wana]

Thanks everyone for your thoughts and input (and drawings). For now, I'm chalking this up to "that's what having a 1960's British car is like" and will report back on any further developments. I appreciate that there are so many good folks willing to comment. That's what makes this board so good. Thank you.

Wana

 

[Bob_Spidell]

Note their warning that they are not compatible with halogen bulbs due to a current limit of 4 amps.

I have LED brake lights; should be considerably less than 4 amps. Anyone using halogen for brakes?

 

[RAC68]

Hi Lin,

I just went to the Ladder Diagram thread (page 2) and the entry I posted with the picture/diagram of the flasher relays. After clicking on "Edit". I double clicked on the picture and was presented with a number of display options including placement and size of picture. I would expect this would work with any system/browser.

Ray(64BJ8P1)