RAWDEAL 222 Posted September 7, 2014 Hi guys i am trying to find a wire that will let me trigger a relay so that when the engine is on , the relay is , even when just cranking I am not sure how to go about it without having a wiring diagram or manual on hand? the oil pressure switch would be the opposite to what i want as its only on when low oil pressure ? I did use the red coil wire but because of the pulses it diddnt work, it just went bezerk lol anyone got any simple ideas on where i can get some +12? Share this post Link to post Share on other sites
VDO 124 Posted September 7, 2014 Alternator warning light circuit should do it. Get it directly from the wire at alternator plug. Alternator warning light gets 12V+ into one side and 12V- the other side so it will light up when the ignition's on and the alternator isn't turning. When the alternator is turning it will then push out + instead of negative. Two positives won't light the lamp, hence the lamp goes out when alternator is turning or the engine is cranking or running. When static, the wire will give negative feed to illuminate the warning lamp, but when the engine's turning it will change to 12 Volt + output. What type/model of car is it..? I should be able to tell you which colour the wire at the alternator is. Share this post Link to post Share on other sites
RAWDEAL 222 Posted September 7, 2014 its a 1993 dc ltd! with the 5.0 in it Share this post Link to post Share on other sites
RAWDEAL 222 Posted September 7, 2014 its a 1993 dc ltd! with the 5.0 in it So basically want Car off > Circuit open Car on/Cranking > Circuit closed Not sure which wire on the alternator to splice into ill have to have a look tommorrow Share this post Link to post Share on other sites
gerg 10,871 Posted September 7, 2014 Try oil pressure switch hooked up to the NC terminal (87a) on a changeover relay. Get power to the relay from ignition not battery. That's failing the above method anyways. Share this post Link to post Share on other sites
xd4.1efisc 34 Posted September 7, 2014 Splice into the fuel pump relay circuit. Fuel pump only runs when cranking, engine running, or for a few seconds when ignition is turned on. 2 gerg and Outback Jack reacted to this Share this post Link to post Share on other sites
RAWDEAL 222 Posted September 8, 2014 Splice into the fuel pump relay circuit. Fuel pump only runs when cranking, engine running, or for a few seconds when ignition is turned on. I would but i am using it to bypass the headfkuc that is with the current LPG wiring , and rewiring the lpg system Atm it works on petrol, but doesnt work when flicked onto gas. Just gonna get an auto elec mate of mine to rewire it for me Share this post Link to post Share on other sites
gerg 10,871 Posted September 8, 2014 Sounds like your interlock relay is stuffed. Don't go bypassing it as it's a safety device that cuts gas supply as soon as the engine stops. Share this post Link to post Share on other sites