=jon= Posted December 29, 2013 Share Posted December 29, 2013 Hi, Quick question - I'm looking for a +12v feed, switched on the ignition that also stays live when cranking. I've metered out the back of the ignition switch - the switched feed drops when you turn it to the crank position... Any suggestions? If it makes any difference, it started off life as a 90 NAD, now it's got a petrol fitted. The coil / fuel pump feed is off the back of the ignition switch, with another feed from somewhere else on the loom powering the coil direct when cranking (bypassing the ballast resistor). It looks like the fuel pump is powered through the ballast resistor, so only gets 6v when cranking... Any suggestions? Cheers Jon Quote Link to comment Share on other sites More sharing options...
discomikey Posted December 29, 2013 Share Posted December 29, 2013 the starter exciter wire is most probably the only "non crank relief" ignition feed to be honest Quote Link to comment Share on other sites More sharing options...
=jon= Posted December 29, 2013 Author Share Posted December 29, 2013 Hmmm - bum One way to get round it would be to swap the ballast coil for a non ballast one, as then the pump would get a proper 12v on cranking, not 6v... Landies are never easy are they! Quote Link to comment Share on other sites More sharing options...
=jon= Posted December 29, 2013 Author Share Posted December 29, 2013 I suppose a big diode across the ballast resistor would work - so in normal operation the juice is forced through the ballast, under cranking it can go via the diode to provide 12v to the fuel pump... Does my logic seem sound? Quote Link to comment Share on other sites More sharing options...
discomikey Posted December 30, 2013 Share Posted December 30, 2013 are you doing a petrol - diesel conversion? Quote Link to comment Share on other sites More sharing options...
=jon= Posted December 30, 2013 Author Share Posted December 30, 2013 Nope! Just looking for a wire that's +ve on ignition and cranking! I would have thought it would have cropped up before as it'd be needed for megasquirt and alarm installs - currently the only way I can think of doing it is with diodes on the ignition feed and from the starter solenoid. Looking at the wiring guide, it seems that the V8's have a complex system to feed the fuel pump while cranking off the starter feed via the oil pressure switch, which mine doesn't have... Quote Link to comment Share on other sites More sharing options...
discomikey Posted December 30, 2013 Share Posted December 30, 2013 the coil/injection pump obviously needs to be non crank relief too so they could be a useable feed Quote Link to comment Share on other sites More sharing options...
=jon= Posted December 30, 2013 Author Share Posted December 30, 2013 A trip to Maplin today yielded some big diodes, which are now wired in parallel across the ballast resistor, so now the fuel pump and electronic dizzy module sees 12v on cranking instead of 6v! When I go megasquirt I can reuse it to provide proper power for that too Quote Link to comment Share on other sites More sharing options...
discomikey Posted December 30, 2013 Share Posted December 30, 2013 ahh top stuff Quote Link to comment Share on other sites More sharing options...
Litch Posted December 30, 2013 Share Posted December 30, 2013 Would using a petrol ignition switch not have sorted it for you? Quote Link to comment Share on other sites More sharing options...
=jon= Posted December 30, 2013 Author Share Posted December 30, 2013 Would using a petrol ignition switch not have sorted it for you? I did look into it - but LRSeries shows conflicting info for which switches fit which - with some listed as fitting both 2.5 petrols and diesels, and some just for the diesels, eg: http://www.lrseries.com/shop/product/listing/1608/579085-IGNITION-SWITCH-ASSY.html?search=ignition%20switch&page=1 From what I can tell the diesel switches should have two spring loaded positions - ignition on, then sprung loaded for glowplugs, then a second for cranking. Mine's got one as per a 'normal' car for cranking only... Mine seems to be a bit of a bitsa 90, with it's non military 2.5NAD VIN, Ford petrol engine and all sorts of other bits changed around, so I'm never sure what's original and what's not! The 2 diodes only cost me a quid and look to have sorted it, so I can't really complain! Quote Link to comment Share on other sites More sharing options...
Litch Posted December 31, 2013 Share Posted December 31, 2013 A NA D has a manual pre-heating position whereas a TDI will have no separate key position as it has auto pre-heat via timer relay. My NA D switch was re-configered when the LRGP 300TDi re-power kit was fitted 9-years ago but earlier this year I eventually got around to fitting a 300TDi ignition switch. If you were to fit a new switch it is really just a case of checking the wiring diagram and also testing connections within the switch with a meter. Quote Link to comment Share on other sites More sharing options...
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