Long Door Posted May 20, 2020 Report Share Posted May 20, 2020 My TR2 side/headlamp switch has failed , the side lights will not switch off. Hardly surprising as its 66 years old. I have attempted a repair to no avail,& have a new switch on the way. I can change the switch without removing the centre dash panel as the bezel is slotted & i can ease the switch body out through the forest of wires .I would like to add an inline fuse on the feed to the light switch. Can anyone advise me the correct size of fuse to use ? I have Wipac quadoptic headlights with 60/55w H4 bulbs. All other bulbs are LED Stay alert( whatever that means) Thanks all Keith Quote Link to post Share on other sites
Lebro Posted May 20, 2020 Report Share Posted May 20, 2020 60W * 2 = 120W, / 14V = 8.6 Amps. so a fuse 10A or more should not normally blow. I would probably go for 15A. That switch failure is caused by grime building up on the part with the brass contacts embedded in it, which slides in & out, the grime becomes conductive, (but with resistance) & when current passes through the "grime" it gets hot. When it get very hot it starts to break down the insulator material underneath (bakelite ?) which also starts to conduct current. No return from that one other than a new switch. Bob Quote Link to post Share on other sites
james christie Posted May 20, 2020 Report Share Posted May 20, 2020 A word of warning - sometime ago there was a bunch of failure prone lighting switches being hawked about. Just test it properly before you fit it. Don.t ask me how I know!! james Quote Link to post Share on other sites
Long Door Posted May 20, 2020 Author Report Share Posted May 20, 2020 Hi James I have ordered my switch from a well known supplier in the middle of nowhere in Somerset, was that the source of your dodgy switch ? Keith Quote Link to post Share on other sites
Long Door Posted May 20, 2020 Author Report Share Posted May 20, 2020 Thanks Bob, I thought as much. By the way your LED lamps are great, as good as any modern DRL Keith Quote Link to post Share on other sites
james christie Posted May 20, 2020 Report Share Posted May 20, 2020 2 hours ago, Long Door said: Hi James I have ordered my switch from a well known supplier in the middle of nowhere in Somerset, was that the source of your dodgy switch ? No Sir it wasn’t. I think it came from a stall in Malvern. But to raise your comfort level, it is rare that something defective comes out of deepest Somerset as they really own and drive TRs. Quote Link to post Share on other sites
ianc Posted May 21, 2020 Report Share Posted May 21, 2020 Beware having just one fuse supplying the lights - if it were to blow, you would be left entirely in the dark! Better to get the headlamps supplied via relays, and put a fuse into each of the 4 headlamp runs (dip & full beam) - this was standard practice on the Works' TR4 Rally cars so that if the car biffed a wall and shorted the supply(s) to the headlamp, then the headlamp on the other side would remain operational. Ian Cornish Quote Link to post Share on other sites
6TTR3A Posted May 24, 2020 Report Share Posted May 24, 2020 IF THAT LIGHT SWITCH IS A LUCAS 314200 IT IS RE-BUILDABLE. Prior owners, not understanding the plan...pull for SIDE lights, twist 20° clockwise & pull again for HEAD. Years of of trying one pull for HEAD and if it wouldn't work, PULL HARDER !! caused wear on the shaft. Unsolder the nut, take it apart in EXACT sequence (very important) Clean everything. Insert a 1 mm plastic washer where indicated. Same diameter as tan & red parts. Re-assemble & it will work properly Quote Link to post Share on other sites
Lebro Posted May 24, 2020 Report Share Posted May 24, 2020 Not if the underlying shaft has started to burn away as a result of overheating. I have seen more than one example of this. Bob. Quote Link to post Share on other sites
Long Door Posted May 29, 2020 Author Report Share Posted May 29, 2020 New switch fitted, all working OK . Thanks Ian for the advice, point taken. Keith Quote Link to post Share on other sites
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