richard lane Posted December 30, 2015 Share Posted December 30, 2015 Hi My brake lights have stopped working, changed fuse and both bulbs just in case but still nothing.All lights are otherwise working as per normal.Any Ideas?Thanks in advance!Rich Link to comment Share on other sites More sharing options...
Titanium7 Posted December 30, 2015 Share Posted December 30, 2015 Switch in pedal box, a common cause. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted December 30, 2015 Member Share Posted December 30, 2015 What Titanium7 says, as the best place to start.It's often possible to fix this without replacing anything. Don't take the switch apart until you've found the notes in the archives... there's a spring which tends to make a break for the Swiss border...Do you have a multimeter already?Jonathan Link to comment Share on other sites More sharing options...
SM25T Posted December 30, 2015 Share Posted December 30, 2015 Easy to fix. Take off top cover of pedal box. Prise end cap off switch carefully and catch the spring inside. Pull out brass piece and squeeze the two legs together a bit, cleaning off any grease that is on the contact part at the end. Reassemble and test. Note spring only fits one way round. If you lost it on opening switch .... hunt for it all day. Link to comment Share on other sites More sharing options...
richard lane Posted December 30, 2015 Author Share Posted December 30, 2015 Thanks will go out and try this!I will let you know the outcome! Link to comment Share on other sites More sharing options...
SM25T Posted December 30, 2015 Share Posted December 30, 2015 Boinggggggggggggg. Link to comment Share on other sites More sharing options...
pugwash Posted December 30, 2015 Share Posted December 30, 2015 I am sure you will try this but before you disassemble the switch connect the two wires together to confirm it is a switch problem! Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted December 30, 2015 Member Share Posted December 30, 2015 Yes, I'd always test before jumping to a specific solution... but for this one, wth one dominant fault, I could just accept it's a matter of style... just... maybe... :-)I'd still use a multimeter rather than shorting the ends.Jonathan Link to comment Share on other sites More sharing options...
richard lane Posted December 30, 2015 Author Share Posted December 30, 2015 Hi guys,Thanks for all the help!Opened up pedal box, and took switch out which was actually quite loose as the retaining screws seemed a bit loose.Anyway it is the switch as it was working on and off as I was playing with. Put it all back together and seems to be all okay.I do not have a multimeter so obviously need to invest in one!Thanks again for the speedy help!Cheers Rich Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted December 30, 2015 Member Share Posted December 30, 2015 Well done.I recommend the Draper 60792.Jonathan Link to comment Share on other sites More sharing options...
DirtBuddha Posted September 9, 2021 Share Posted September 9, 2021 Resurrecting an older thread... my brake lights have stopped working, 2 weeks after the MOT :-( I have taken out the switch, disassembled and cleaned it per the steps above but still no worky.I then put a test light (one of those screwdriver/probe type things with a small crocodile clip at one end and a probe at the other) connecting the 2 wires and it lights up. However the brake lights don't come on when the test light/probe is connected - whether the pedal is depressed or not. Would you expect the brake lights to come on when the 2 wires are connected with a probe and the brake pedal depressed (or not)? Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted September 9, 2021 Member Share Posted September 9, 2021 "Would you expect the brake lights to come on when the 2 wires are connected with a probe and the brake pedal depressed (or not)?"Yes. But you don't need the probe for that: the brake lights should come on when you short the two sides of the switch together (with the ignition on).It sounds as if one side of the switch is live, but I don't know what your probe does, so if in any doubt check the brake light fuse.Any recent work or other problems, and are all the other lights working?Have you got a multimeter, and would you like a wiring diagram?Jonathan Link to comment Share on other sites More sharing options...
DirtBuddha Posted September 9, 2021 Share Posted September 9, 2021 I'll check the fuse next then. I do have a multimeter, which someone gifted me a few years ago - but I don't know how to use it(!).I am absolutely HOPELESS when it comes to electrics. I can just about manage a test light. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted September 9, 2021 Member Share Posted September 9, 2021 You'll only need a couple of functions of the multimeter: checking for whether a point of interest is live compared to a good earth, and checking for continuity of a circuit. Let's do this one step at a time, but do you have the wiring diagram for your Seven?Any recent work or other problems, and are all the other lights working?Jonathan Link to comment Share on other sites More sharing options...
DirtBuddha Posted September 9, 2021 Share Posted September 9, 2021 Really appreciate your help Jonathan! The brake lights weren't working when I got the car 4 months ago, so I checked all the fuses in the fuse panel (all ok), removed the boot floor, cleaned up all the connections, removed the light lenses and bulbs, made sure they were all clean etc and they started working. Since then, I had the LED Lifeline high-level rain light wired in (by a Caterham specialist) to the brake lights while the car was in for a service, in order to turn it into a high-level LED brake light. The brake lights have worked fine since then, but stopped working sometime this week (I don't know exactly when, as I just noticed them last night). I don't have a wiring diagram for my car but would appreciate one. Mine is a 2015 ex Academy car (Ti-VCT Sigma). Link to comment Share on other sites More sharing options...
SM25T Posted September 9, 2021 Share Posted September 9, 2021 Make sure there is no long leg on a split pin at the top of the clutch pedal ... if it touches contacts on brake light switch, it can blow the fuse. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted September 9, 2021 Member Share Posted September 9, 2021 Thanks for the extra information.Private Message sent.Jonathan Link to comment Share on other sites More sharing options...
John Vine Posted September 9, 2021 Share Posted September 9, 2021 I take it the bulbs are ok?Is your high-level brake light connected into the brake-light circuit via a special loom (like this)? If so, check that the connectors are firm and that the terminals inside are properly aligned. Sometimes they can become dislodged, with a resultant poor contact.JV Link to comment Share on other sites More sharing options...
DirtBuddha Posted September 9, 2021 Share Posted September 9, 2021 I've just been out to check all the fuses in the panel (removing them 1 by 1) - all are ok. I've removed the boot floor, disconnected the multiplugs for each rear light cluster, visually checked for anything burnt/corroded (all ok), then sprayed a little WD40 into each side and reattached. Still nothing.... I'll check the bulbs and clutch split pin in the morning light, and will double-check the subloom for the Lifeline high-level rain light. Link to comment Share on other sites More sharing options...
DirtBuddha Posted September 9, 2021 Share Posted September 9, 2021 @Jonathan Kay - your mailbox is full so cant reply to your msg. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted September 9, 2021 Member Share Posted September 9, 2021 Sorry.Jonathan Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted September 9, 2021 Member Share Posted September 9, 2021 Update imminent...Jonathan Link to comment Share on other sites More sharing options...
DirtBuddha Posted September 10, 2021 Share Posted September 10, 2021 I can't thank Jonathan Kay enough for his help in diagnosing the problem. As BC was ‘down’ this morning we communicated via email, but I have posted Jonathan's and my conversation below for future reference - in the hope that this may of help in future to people who, like me, are complete numpties when it comes to electrics! Jonathan advised using a multimeter to test the brake light switch. I was gifted a multimeter some time ago but (shamefully) I didn’t even know how to work it! Before you all laugh, I’m ok mechanically… I’ve taken engines, gearboxes, suspension, diffs and all manner of things apart and rebuilt them, I even built a Land Rover Defender 90 from scratch - every single nut and bolt - 20 years ago. But when it comes to electrics, I’m completely lost, it’s always been a black art to me. My email provider has somehow lost Jonathan’s first email, but he told me to turn the multimeter to any setting that measured voltage, put the red probe on the positive battery terminal and the black one on the negative and see if it read anything like 12v-13v. It did. Then to do the same at the brake light switch (jam a probe into each side terminal and see what it read). Morning Jonathan, I’ve done as you said and used the multimeter. On the battery it read 12.85 and at the brake light switch with the probes jammed into the terminals it reads 12.34v - very slightly lower than the reading at the battery. I’ve taken the bulbs out and they look fine. I cleaned up the Earth on the inside of each light cluster but they weren’t bad, I only did so because I hear 99% of all problems are earth related.Still no joy. -S OK… the multimeter is working and you’ve got the right range.Put the black probe on the battery negative terminal and keep it there.Then the red probe on one side of the switch: what voltage does it show?Then the red probe on the other side of the switch: what voltage does it show?And what colours are the wires on each side of the switch?The ignition needs to be ON for this test.-J Okay, with the ignition on and doing as you’ve described the multi meter reads 12.22 when the probe is on the side with the 2 wires (red wire + plain green wire) It reads nothing at all with the probe on the side with the single green wire with purple stripe. -S You now know the input and output side of the switch and that it has a live feed at the input side.Green is the ignition-switched feed, and Green/ Purple goes from the switch to the lights. I don’t know what the red wire is.With the ignition ON:Leave the black probe on the battery negative. Put the red probe on the OUTPUT side of the switch. Press the switch fully in by hand.What happens to the voltage at the OUTPUT side of the switch?And while you’re doing that see if the brake lights are coming on when you press the switch fully in by hand.-J Jonathan, you really are teaching a man how to fish rather than giving him a fish. This is hugely appreciated! So, doing what you say, with the red probe on the output side of the switch and the black probe on the battery negative terminal, when depressing the plunger on the brake switch nothing at all happens to the voltage - it just says 0.00. Also, when pressing the switch nothing happens at the lights.-S That’s the idea!Sounds as if the switch is bust.To confirm that now switch the multimeter to a resistance range, one in the section with an Ω.Touch the two probes together and it will show the low resistance and continuity. Then do the same on any piece of bare metal so that you’re familiar with the response.Disconnect all the wires from the switchCheck that you get continuity when you put both probes on the same side of the switch terminalNow put one probe on one of the switch terminals and one on the other.On a working switch there’ll be no continuity until you press the switch in and then there will be… what happens on yours?-J So when I do that the multimeter shows the number 1 when the probes aren’t connected to anything. When I touch the ends of the probes together the numbers change rapidly and then settle to 001. Is that correct?I am a complete moron and I don’t know what continuity is, but when I do as you say and put both probes on one terminal on one side of the brake light switch the same thing happens, i.e. the numbers fluctuate and then settle down to 001. This is the same for both terminals i.e. on each side of the brake light switch. Re your last paragraph, when I put a probe on each terminal on the switch the multimeter reads the number 1 and when I press the plunger on the switch it stays the same, nothing happens, it still reads the number 1. -S You’re doing it right.That 1 means high resistance/ open circuit/ no continuity.That .001 means low resistance/ good continuity.Nothing happening to continuity when the switch is pressed in confirms that the switch isn’t working.Please see next email.-J It’s common for these switches to fail.A better model is available:https://www.lotus7.club/forum/techtalk/brake-light-switch-14 But it might be mendable. You can take them apart and have a look, but BEWARE… there is a little spring that makes a bid for freedom when you open the switch, so this needs to be done deep in a box. Same thread as above:https://www.lotus7.club/forum/techtalk/brake-light-switch-14 -J Link to comment Share on other sites More sharing options...
SM25T Posted September 10, 2021 Share Posted September 10, 2021 Fixing the CC brake light switch is a 5 minute job. The spring isnt that ferocious at all, just prise end cap out gently and keep your hand over to restrain the small spring. You'll find a u-shaped contact inside ... the legs just need squeezing together a little. Clean any greasy gunk off them. Link to comment Share on other sites More sharing options...
OldAndrewE Posted September 10, 2021 Share Posted September 10, 2021 "I’ve taken the bulbs out and they look fine" Obviously not the issue in this case as the fault has been found but a broken bulb is not always obvious to the eye if the filament has broken due to a knock or similar. Better to check by connecting to a known good supply, e.g. the battery 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