68vitesse Posted July 12, 2019 Report Share Posted July 12, 2019 Out in the Vitesse this afternoon, told by van driver brake light not working, stopped to check all seemed ok. When I got home checked again lights not working, checked switch with meter switch intermittent. Now have Lucas SMB429 fitted which has a metal case as against the all plastic case old one, not my first problem with brake switches, so hopefully more reliable. Would be easy to fit a tell tale light in my supplementary panel or is that being paranoid?. Regards Paul Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 12, 2019 Report Share Posted July 12, 2019 The plastic switches from my perspective should have a deep nut so the pedal sits aganst the nut face not rely on the switch plunger to Arrest the pedal as a back stop A tell tail,says the circuit works but wont tell if all bulbs have died. Pete Link to comment Share on other sites More sharing options...
68vitesse Posted July 12, 2019 Author Report Share Posted July 12, 2019 Switch is set so that I can still depress the plunger with the pedal fully up, and to have both bulbs fail at the same time would be unlucky. The only trouble l have had with the circuit has always been the switch. Regards Paul Link to comment Share on other sites More sharing options...
Colin Lindsay Posted July 13, 2019 Report Share Posted July 13, 2019 11 hours ago, 68vitesse said: Switch is set so that I can still depress the plunger with the pedal fully up I'm not sure what you mean by this, but if you can activate the brake lights with the pedal fully up, doesn't this mean undue strain on the switch when you do press the pedal? I'm skirting round any problems with my early Herald and fitting the hydraulic brake switch directly into the brake lines, as per original. Link to comment Share on other sites More sharing options...
RogerH Posted July 13, 2019 Report Share Posted July 13, 2019 15 hours ago, 68vitesse said: Out in the Vitesse this afternoon, told by van driver brake light not working, stopped to check all seemed ok. When I got home checked again lights not working, checked switch with meter switch intermittent. Now have Lucas SMB429 fitted which has a metal case as against the all plastic case old one, not my first problem with brake switches, so hopefully more reliable. Would be easy to fit a tell tale light in my supplementary panel or is that being paranoid?. Regards Paul Hi Paul, this BMW switch fits onto the TR's a treat, is nearly half the price of the plastic ones that fail so quickly AND lasts for ages. Roger Link to comment Share on other sites More sharing options...
Colin Lindsay Posted July 13, 2019 Report Share Posted July 13, 2019 This is the one I used most recently; for SAAB, BMW and Volvo. A straight fit and seems good enough so far. Link to comment Share on other sites More sharing options...
RogerH Posted July 13, 2019 Report Share Posted July 13, 2019 14 hours ago, Pete Lewis said: A tell tail,says the circuit works but wont tell if all bulbs have died. Pete Hi Pete, A 'tell tale' will work if you have some sort of current sensing circuit. On my TR4A I have the power wire to the brake lights wound around a normally open reed switch. Reed Switch The reed switch powers a LED on the dash (one for each light) This circuit does not rob the lights of precious volts If you want more info just ask Roger Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 13, 2019 Report Share Posted July 13, 2019 thats a good idea, being a dinosaur i get out and check my lights and reflections in the garage door etc , this works without any techy , club shop also sell a metal replacement looking at the number of cars with duff brake , side and headlamps seems most like to drive around in the dark and invite rear ends around here its rife roads full of.............. pratts pete Link to comment Share on other sites More sharing options...
68vitesse Posted July 13, 2019 Author Report Share Posted July 13, 2019 9 hours ago, Colin Lindsay said: I'm not sure what you mean by this, but if you can activate the brake lights with the pedal fully up, doesn't this mean undue strain on the switch when you do press the pedal? I'm skirting round any problems with my early Herald and fitting the hydraulic brake switch directly into the brake lines, as per original. Don't understand, switch is contacts closed when plunger fully extended, pedal depressed. If the pedal is fully up and I can depress the plunger all it means is the pedal is not using the switch as a stop. Don't think Vitesse 2L ever used a hydraulic brake light switch. Regards Paul Link to comment Share on other sites More sharing options...
Colin Lindsay Posted July 13, 2019 Report Share Posted July 13, 2019 43 minutes ago, 68vitesse said: Don't understand, switch is contacts closed when plunger fully extended, pedal depressed. If the pedal is fully up and I can depress the plunger all it means is the pedal is not using the switch as a stop. Don't think Vitesse 2L ever used a hydraulic brake light switch. Regards Paul It's the way you've worded it that's throwing me a bit - I would picture it that if the pedal is pushed down, then the switch plunger is also depressed. Extended to me means in the open position ie pedal is at rest and brake lights are off, and the plunger fully extended out of the end of the body. That's why when you said you can depress the plunger with the pedal fully up - as opposed to down when you put your foot on it - I took it to mean that you can activate the switch with the pedal in the rest position and thereby, yes, there would be enormous pressure on the switch when it came to actual braking. It's just the wording - I can picture it now. And no, the Vitesse never used hydraulic braking, which is why I'm doing it on a Herald....! Link to comment Share on other sites More sharing options...
NonMember Posted July 15, 2019 Report Share Posted July 15, 2019 On 13/07/2019 at 18:37, Colin Lindsay said: I would picture it that if the pedal is pushed down, then the switch plunger is also depressed. No, they are "normally closed" switches, so the plunger is depressed to open the contacts, by the pedal in its rest position, fully up. Link to comment Share on other sites More sharing options...
RogerH Posted July 15, 2019 Report Share Posted July 15, 2019 Hi Rob, on the TR series, and I would have thought all others, the switch is Normally Closed (NC) when on the shelf. However the switch is adjusted so that the switch plunger is depressed and thus becomes Open Circuit with the brake pedal not operated. When you press the pedal the switch plunger is pushed out under spring pressure to move into the Normally Closed position and operate the lights. Roger Link to comment Share on other sites More sharing options...
NonMember Posted July 15, 2019 Report Share Posted July 15, 2019 Hi Roger, I think you are just agreeing with me but your use of "However" feels odd. In electrical or electronic engineering, the terms "normally open" and "normally closed" always denote the switch's behviour "on the shelf", as you put it. What you do mechanically and how you employ it are irrelevant. A normally closed switch that spends most of its life being depressed is still "normally closed" regardless of how long it spends being open. <massive thread drift>Of course, being open when you're depressed is a good thing, as long as you're in the right environment. Link to comment Share on other sites More sharing options...
Colin Lindsay Posted July 15, 2019 Report Share Posted July 15, 2019 Light has dawned on marble head. The switch points downward, the contacts are held open by the pedal at rest, and when it is pressed downwards, the plunger moves out and makes contact. I kept picturing it as a switch that was pressed IN by the pedal moving downwards - no idea why as I've replaced more than a few in my time - therefore Paul's post confused me as a pedal at rest would, in my mind's eye with the backward fitting, be off the plunger completely. Make allowances for advancing years and a slowing brain, please.... Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 15, 2019 Report Share Posted July 15, 2019 I had the light dawn but it was me nodding off in the 2000 with the 48 LED interior lamp on Pete Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now