Paul H Posted July 18 Report Share Posted July 18 Vitesse mk2 , Speedo has been out to change Speedo cable . Everything back BUT ignition light won’t come on with the key turned . Engine turns over and starts fine . If I earth the bulb assembly on temp basis the light comes on . Any ideas? Paul Link to comment Share on other sites More sharing options...
johny Posted July 18 Report Share Posted July 18 Must be a problem with the brown/yellow wire going from bulb to regulator (dynamo still used?). Has it broken at the bulb holder? 1 Link to comment Share on other sites More sharing options...
Paul H Posted July 18 Author Report Share Posted July 18 8 minutes ago, johny said: Must be a problem with the brown/yellow wire going from bulb to regulator (dynamo still used?). Has it broken at the bulb holder? I’ve upgraded to an Alternator though nearly 2 years ago . I’ll check the brown/yellow cable Paul Link to comment Share on other sites More sharing options...
Paul H Posted July 18 Author Report Share Posted July 18 2 hours ago, Paul H said: I’ve upgraded to an Alternator though nearly 2 years ago . I’ll check the brown/yellow cable Paul Bulb is ok. Brown/Yellow traces back to old defunct regulator which in turn is connected Brown/Green which is terminated as no longer in use with the Denso so can’t understand what this cable does ? . Car starts fine though no ignition light unless it touched earth and then stays on . Alternator is charging as battery check says 14.1 Paul Link to comment Share on other sites More sharing options...
Graham C Posted July 18 Report Share Posted July 18 On the GT6 there is a black cable with a ring that acts as an earth by being held in place knurled but on one of the clamps. Have you're fitted this? Graham Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 18 Report Share Posted July 18 (edited) well in simple the big terminal feeds the battery via the starter solenoid terminal the small terminal feeds the warning lamp which must have a dash board earth the old regulator is best removed or at the regulator join all big terminals together join the small terminals together dump the black earth not required but best to upgrade the harness and use the shortest route Edited July 18 by Pete Lewis Link to comment Share on other sites More sharing options...
johny Posted July 18 Report Share Posted July 18 The bulb has to connect to the alternator somehow so that battery power can flow through the ignition bulb and down to earth through it. Then when the alternator rotates and produces output its voltage opposes the bulb current flow and it goes out. Unlike the other bulbs it shouldnt need the earth connection at the speedo.... It is still a filament bulb isnt it, not LED? Link to comment Share on other sites More sharing options...
Paul H Posted July 18 Author Report Share Posted July 18 4 minutes ago, johny said: The bulb has to connect to the alternator somehow so that battery power can flow through the ignition bulb and down to earth through it. Then when the alternator rotates and produces output its voltage opposes the bulb current flow and it goes out. Unlike the other bulbs it shouldnt need the earth connection at the speedo.... It is still a filament bulb isnt it, not LED? I have tried both filament and LED Paul Link to comment Share on other sites More sharing options...
Paul H Posted July 18 Author Report Share Posted July 18 11 minutes ago, Graham C said: On the GT6 there is a black cable with a ring that acts as an earth by being held in place knurled but on one of the clamps. Have you're fitted this? Graham On the Speedo the ignition light plus the Head lamp flash and oil light bulbs are housed in plastic so they are not earthed Paul Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 18 Report Share Posted July 18 so they must have a seperate earth wire on the bulb holder or they cant work Pete Link to comment Share on other sites More sharing options...
johny Posted July 18 Report Share Posted July 18 Inside the regulator the ignition bulb wire NY on terminal W/L is connected directly to the terminal D which originally had a NY wire going off to the dynamo. Could this now be used to illuminate the bulb? Link to comment Share on other sites More sharing options...
Paul H Posted July 18 Author Report Share Posted July 18 1 hour ago, johny said: Inside the regulator the ignition bulb wire NY on terminal W/L is connected directly to the terminal D which originally had a NY wire going off to the dynamo. Could this now be used to illuminate the bulb? I’ll try this but what I don’t understand is what I’ve done is take out the Speedo and put it back . Before the ignition bulb has worked for years without issue Paul Link to comment Share on other sites More sharing options...
johny Posted July 18 Report Share Posted July 18 so if you earth the NY wire from the bulb at the regulator it lights up proving the ignition circuit to that point? As I say it could have broken somewhere while you were removing the speedo.... Link to comment Share on other sites More sharing options...
johny Posted July 19 Report Share Posted July 19 Any progress Paul? Dont want to teach granny to suck eggs but are you sure youve got the bulb holders in the right place - oil pressure is brown/white and ignition brown/yellow so very easy to mix up after 50 years and in the gloom behind the speedo😲 Link to comment Share on other sites More sharing options...
Paul H Posted July 19 Author Report Share Posted July 19 3 minutes ago, johny said: Any progress Paul? Dont want to teach granny to suck eggs but are you sure youve got the bulb holders in the right place - oil pressure is brown/white and ignition brown/yellow so very easy to mix up after 50 years and in the gloom behind the speedo😲 Still can’t work out what’s wrong . Ive got the correct bulb ie brown / yellow and white cable . The NY cable is linked to NG and this cables terminates close to the alternator but not attached to anything . You mentioned linking the NY to D . I tried to temp link with NY to the Denso and the only exposed cable was the output at the top ( this links direct to the battery with a 30 amp cable ) When testing I always run a low amp fuse which blew as soon as I flicked the ignition . The ignition light when earthed will light up on ignition but stay on with the engine running. The alternator is charging . As mentioned before the ignition system has operated for the last 2,000 miles but not since I removed and replaced the Speedo cable Paul Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 19 Report Share Posted July 19 so where is the warning light getting its power from ???? can you run a single test lead from the denso small terminal direct to the WL ?? Pete Link to comment Share on other sites More sharing options...
johny Posted July 19 Report Share Posted July 19 well the white wire on the bulb brings the power in from the battery via the ignition switch. However something strange is happening with the negative side brown/yellow wire which looks as if it was never connected to anything but the bulb used to illuminate! Link to comment Share on other sites More sharing options...
Colin Lindsay Posted July 19 Report Share Posted July 19 39 minutes ago, Paul H said: Still can’t work out what’s wrong . Ive got the correct bulb ie brown / yellow and white cable . The NY cable is linked to NG and this cables terminates close to the alternator but not attached to anything . You mentioned linking the NY to D . I tried to temp link with NY to the Denso and the only exposed cable was the output at the top ( this links direct to the battery with a 30 amp cable ) When testing I always run a low amp fuse which blew as soon as I flicked the ignition . The ignition light when earthed will light up on ignition but stay on with the engine running. The alternator is charging . As mentioned before the ignition system has operated for the last 2,000 miles but not since I removed and replaced the Speedo cable Paul Wonder if it was actually earthing via the old speedo cable? Link to comment Share on other sites More sharing options...
johny Posted July 19 Report Share Posted July 19 But it used to go out when engine started and alternator generating😲 Link to comment Share on other sites More sharing options...
Paul H Posted July 19 Author Report Share Posted July 19 12 minutes ago, Colin Lindsay said: Wonder if it was actually earthing via the old speedo cable? I don’t think it could earth as the ignition housing on the Speedo is plastic , so the issue must be the brown/ yellow cable so going see where it terminates . Should be close to alternator Thanks for everybody’s help so far - appreciated Paul Link to comment Share on other sites More sharing options...
Paul H Posted July 19 Author Report Share Posted July 19 (edited) Tracked the brown/green in the loom and still has spade for the original dynamo . Should I make a temp connection with the brown/green to the large diameter brown / yellow cable which feeds the alternator ? Confirming there is continuity through to ignition bulb Paul Edited July 19 by Paul H Link to comment Share on other sites More sharing options...
johny Posted July 19 Report Share Posted July 19 one of those 3 plug connections is the wire from the ignition light, I think its the left one but best to check up, so should join with the brown/green wire somewhere... Link to comment Share on other sites More sharing options...
Paul H Posted July 19 Author Report Share Posted July 19 Put a temp connection with brown yellow ( from bulb) to large brown yellow. Result was ignition light came on plus some ancillaries eg dash cam . Using key turned to position 1 ( ie no starter ) Result. Oil light came on and ignition light went off. Paul Link to comment Share on other sites More sharing options...
Paul H Posted July 19 Author Report Share Posted July 19 The 3 plug connections on the alternator are left . Brown . Dedicated feed to positive on battery middle. White . + VE side of Coil right . Thick brown yellow Paul Link to comment Share on other sites More sharing options...
johny Posted July 19 Report Share Posted July 19 Its got to be like this: Link to comment Share on other sites More sharing options...
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