Ralph Posted September 13, 2021 Share Posted September 13, 2021 Hi AllJust installed the new Caterham rear light kit, look great but still working on getting the reverse light to work.As for the reversing light I am confused as I don’t seem to have the normal set up, the switch only has one pop stud connector (see photos), and on top of that the wire does not show any power (tried with ignition on checked fuse but nothing). At the other end two wires presumably one live and one earth but they are the same colour green.Questions1. would this switch work with the new lights anyway?3. If all else fails I am thinking of changing the switch to the normal 2 pin and rewiring. Any ideas on the easiest way to do this.Just need a few ideas in case I am missing something obvious as I am not an auto electrician. Link to comment Share on other sites More sharing options...
Jonathan Kay Posted September 13, 2021 Share Posted September 13, 2021 On the reversing light switch:It's known that the factory wired this in two different ways.Can you see the colour of the wire to that connector?With one connector like that I'd suspect that it's switching the light to earth. You can test that with a multimeter or by disconnecting the wire and touching that directly to the gearbox and seeing if the light comes on, might need ignition ON. That would need to be the old light.If it is this then there shouldn't be any power there, see next post.Would you like the wiring diagram for your Seven?Jonathan Link to comment Share on other sites More sharing options...
Jonathan Kay Posted September 13, 2021 Share Posted September 13, 2021 "At the other end two wires presumably one live and one earth but they are the same colour green."Green is conventionally a live feed to accessories switched with the ignition. Where is "the other end"... at the lamp unit?With a switched earth circuit there needs to be a live feed to the lamp unit. It then lights up when the earth side from the lamp unit is connected to earth by the switch eg in the gearbox.Jonathan Link to comment Share on other sites More sharing options...
Jonathan Kay Posted September 13, 2021 Share Posted September 13, 2021 "Questions1. would this switch work with the new lights anyway?3. If all else fails I am thinking of changing the switch to the normal 2 pin and rewiring. Any ideas on the easiest way to do this."Let's confirm what you've got, as above. Then look at the options. NB LED units usually have to be connected the right way round.Jonathan Link to comment Share on other sites More sharing options...
Beagler Posted September 13, 2021 Share Posted September 13, 2021 Mine has bulbs in rear lights except numberplate light and that came with LED. Link to comment Share on other sites More sharing options...
John Vine Posted September 13, 2021 Share Posted September 13, 2021 I've not seen a reversing-light switch like that before. What model of car do you have?Running through CC's instruction video (very good, by the way!) for the LED rear-light kit, the first thing that struck me was that the kit connectors for both fog light and reversing light had single wires (r/l = green, fog = orange). So, presumably, only the 12v supply is carried forward and the old earth is redundant. CC claim that the kit fits all models....the wire does not show any power (tried with ignition on checked fuse but nothing). Assuming this is the 12v supply, did you engage reverse gear first?It then lights up when the earth side from the lamp unit is connected to earth by the switch eg in the gearbox.I got the impression from the video that there isn't an earth wire, just a single 12v line. So, if your switch wire (with the popper) is an earth line, I can see why the light wouldn't work.JV Link to comment Share on other sites More sharing options...
Leadership Team SLR No.77 Posted September 14, 2021 Leadership Team Share Posted September 14, 2021 Ralph, what age is your car? I've fitted the new light kit to my 1999 car and it's all just plug and play, the new loom connects to the various econoseal connectors as per the original lights, the only difference being that the original numberplate wire is no longer used.Having had a 1995 car previously I would have had to add the various plugs to the loom to update it to post- '96 wiring spec before fitting the new kit, fairly straightforward though with the correct connectors and tools. Pre-'96 wiring is very different though to current cars and certainly had a permanent feed to the reversing light, illuminating when switched to earth at the gearbox.To add ... Caterham fail to mention in their instruction video that you'll do a much better job with the boot floor removed, enabling the new loom to be fed above the fuel tank support brackets at each end of the tank. Stu. Link to comment Share on other sites More sharing options...
TomB Posted September 14, 2021 Share Posted September 14, 2021 Confirm the reversing light earths through the gearbox, so its a single wire only on my 1995/early 96 car. Link to comment Share on other sites More sharing options...
Jonathan Kay Posted September 14, 2021 Share Posted September 14, 2021 "Confirm the reversing light earths through the gearbox, so its a single wire only on my 1995/early 96 car. "Thanks. And looks like that connector?Jonathan Link to comment Share on other sites More sharing options...
Leadership Team SLR No.77 Posted September 14, 2021 Leadership Team Share Posted September 14, 2021 Yes Link to comment Share on other sites More sharing options...
Jonathan Kay Posted September 14, 2021 Share Posted September 14, 2021 ThanksJonathan Link to comment Share on other sites More sharing options...
Jonathan Kay Posted September 14, 2021 Share Posted September 14, 2021 "Questions1. would this switch work with the new lights anyway?3. If all else fails I am thinking of changing the switch to the normal 2 pin and rewiring. Any ideas on the easiest way to do this."..."Let's confirm what you've got, as above. Then look at the options. NB LED units usually have to be connected the right way round."...Assuming that you've got that earth-switched arrangement what wires have you got emerging at the rear end of the car? And what are the relevant wires on the new lamp unit?Jonathan Link to comment Share on other sites More sharing options...
Ralph Posted September 14, 2021 Author Share Posted September 14, 2021 Thanks JonathanWent through your suggestions and I now know what is going wrong.Sometimes you lose you way and it helped to read your post and made me think logically.As suggested I rewired an old lamp back and took the connection of the switch and ground to the gearbox. (Light came on !). Re connected the connector to switch and light came on (Puzzled).Used a circuit tester and the answer to the why plunging in to the new loom does not work is now apparent the original connection on the old loom is back to front to what I would expect (In the Picture the wire with the masking tape is black (This is the live wire the green is earth). see photoI always thought Black was supposed to be earth?So I assume all I have to do is swap the pins round in the plug so live connects to the green wire on the new loom plug.In the new loom you only have one wire for both the Reverse light and the Fog Lamp so assume the earth is within the new units.My car is 1996 and uses the Econoseal type connectors. Also I had to run the new loom along the chassis at front of the fuel tank as the gap is too small at the back (not enough room to feed new Reverse Light / Numberplate light through). If you have a newer car as Stu said in his post you might be better off taking the boot floor off. Thanks all for chipping in as it helped a lot. Link to comment Share on other sites More sharing options...
John Vine Posted September 14, 2021 Share Posted September 14, 2021 (Puzzled)Perhaps reverse was still engaged?So I assume all I have to do is swap the pins round in the plug so live connects to the green wire on the new loom plug.Or swap the green on the new connector, moving just one pin rather than two!JV Link to comment Share on other sites More sharing options...
ScottR400D Posted September 14, 2021 Share Posted September 14, 2021 Possibly a little late but for what it's worth I ran the new loom on the top of the fuel tank away from all the crap. As you say the new reverse/plate light connector won't fit up between the tank and the back panel, but it's simple enough to remove the connector, feed the wire through and refit. Link to comment Share on other sites More sharing options...
Jonathan Kay Posted September 15, 2021 Share Posted September 15, 2021 "Used a circuit tester and the answer to the why plunging in to the new loom does not work is now apparent the original connection on the old loom is back to front to what I would expect (In the Picture the wire with the masking tape is black (This is the live wire the green is earth). see photo"I always thought Black was supposed to be earth?"I'm not quite sure what you're seeing, but it sounds like progress. Please document it all and keep us informed. : - )"Standard" colours: Black should be earth. Green should be live switched with the ignition. Green/ Brown should connect the reversing light switch to the reversing lamp.From Caterham's wiring diagrams:Reversing light switch with one connection: (And this must be a switched earth) Green/Brown from reversing light switch to reversing light ... so the wires from the chassis loom to be connected to the lamp unit are Green and Green/Brown.Reversing light switch with two connections: Green to reversing light switch (so this is a switched live) Green/ Brown from reversing light switch to reversing light ... so the wires from the chassis loom to be connected to the lamp unit are Green/Brown and Black.Please could you check if one of your original wires is Green/Brown rather than Green.ThanksJonathan Link to comment Share on other sites More sharing options...
Ralph Posted September 15, 2021 Author Share Posted September 15, 2021 Hi JonathanAlso this may be useful to anybody else who has the same single wire reverse light switch as meDOUBLE CHECKED EVERYTHING1.Single wire from loom to g/box Green with Brown strip2.Connector at rear of car is 2 wires one Green/Live & one Green & Brown Earth (Could hardly make out the brown stripe).3.I moved the position of the connector pins so Green now connects to the green wire from the new loom.GOOD NEWS Reversing light worksBAD NEWS Reversing light stays on when not in reverse.My Conclusion would be if you have a Reversing light with one connection you will have to change the switch to a two pole type and earth the second pole to part of the car. If you want to fit the new Rear Light KitWould like to hear which switch to buy as not much room to play with in-between chassis and Type 9 G/boxJonathan please shoot me down in flames if you think I am on the wrong track. Link to comment Share on other sites More sharing options...
Jonathan Kay Posted September 15, 2021 Share Posted September 15, 2021 You might not need a new switch (and the related new wiring). That sounds as if the lamp unit is getting an earth connection all of the time, rather than only when the switch is closed.First disconnect the lamp unit and check whether the Green/ Brown wire from the chassis loom is connected to earth all of the time rather than only when the switch is closed.But if that isn't the fault: I don't know how the new kit is wired... but I'd investigate along these lines... is the lampholder earthed other than through the Green/ Brown wire... is a common earth wire shared with another part of the lamps, possibly in the new subloom... etc.Jonathan Link to comment Share on other sites More sharing options...
OldAndrewE Posted September 15, 2021 Share Posted September 15, 2021 You should not need a new switch unless the old one is faulty. Both new and old lights have a 12v supply that is energised when reverse is engaged (with ignition on) so as long as the new light is connected with correct polarity then it should work . I assume the old light worked correctly Link to comment Share on other sites More sharing options...
Jonathan Kay Posted September 15, 2021 Share Posted September 15, 2021 "You should not need a new switch unless the old one is faulty. Both new and old lights have a 12v supply that is energised when reverse is engaged (with ignition on) so as long as the new light is connected with correct polarity then it should work. I assume the old light worked correctly"AIUI Ralph has a gearbox switch that switches the earth side, not the 12v live side,Jonathan Link to comment Share on other sites More sharing options...
John Vine Posted September 15, 2021 Share Posted September 15, 2021 If it helps, here's my understanding of what's going on ( I hope this is legible). Please shout if I've got something wrong!Ralph's wiring is on the left (switch-to-earth at gearbox). Top left is what he started with, and bottom left is after fitting the LED kit. On the right is the later 2-terminal reversing light switch, before and after fitting the LED kit.The reversing light (R/L) connector in the kit has just one wire (green). This connects at A, but ends up with a circuit via the R/L earthed at both ends. Ralph then moved the single green wire to B. This lights the R/L ok, but with or without the R/L switch.If I'm right, I don't see any way of avoiding the need for a 2-terminal R/L switch. However, CC claim that the LED kit works with all models, so something doesn't stack up.JV Link to comment Share on other sites More sharing options...
Jonathan Kay Posted September 15, 2021 Share Posted September 15, 2021 Thanks, John.Your lower left picture addresses the question I asked in #20 (assuming that the gearbox end is OK). But I think that it's now connected the other way round: Green to Green giving the always-on live feed.The light is staying on because of that other earth. If we can find where it is and remove it then the only earth will be through the Green/Brown wire coming from the gearbox and will be switched by the gearbox switch. The live feed will be permanently connected through the Green wire. No changes will be needed to the switch or the wiring at the gearbox. NB polarity for the lamp unit.So where is that earth in the new light kit... is it a wire that isn't connected to anything except the LED reversing lights?Jonathan Link to comment Share on other sites More sharing options...
John Vine Posted September 15, 2021 Share Posted September 15, 2021 But I think that it's now connected the other way round: Green to Green giving the always-on live feed. Exactly so. ...where is that earth in the new light kit..Short of asking CC for a wiring diagram, I guess the only way would be to dismantle the new loom and see what goes where. Is the OP willing to do that?JV Link to comment Share on other sites More sharing options...
Jonathan Kay Posted September 15, 2021 Share Posted September 15, 2021 Can anyone post some pictures of the new reversing lamp unit and the new lighting subloom, please? And the instructions and any diagrams that come with it. I hope that we can find the earth wire for the reversing lamp and then ensure that it's only connected to the Green/Brown wire from the gearbox switch.Jonathan Link to comment Share on other sites More sharing options...
Leadership Team SLR No.77 Posted September 15, 2021 Leadership Team Share Posted September 15, 2021 By adding a relay I "think" it can be done like this, excuse the lousy diagram: If someone can suggest the correct relay pin numbers?Stu. Link to comment Share on other sites More sharing options...
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