24OZ Posted December 21, 2008 Share Posted December 21, 2008 I am starting to wire up my MS to the relay board. I have a circuit test light and when I touch the 12V power terminal for the relayboard and then the 12V + injector terminals I'm surprised the light doesn't come on. I thought that these were all connected and a circuit should have been formed. I thought that there is constant power going to the 12V + terminals for the injectors as they are driven by Inject 1 and Inject 2 negative terminals. Thanks, Quote Link to comment Share on other sites More sharing options...
naviathan Posted December 21, 2008 Share Posted December 21, 2008 Check the injectors 12V against a chassis ground and then check the 12V on the relay board the same way. I might wrong, but the way you described this problem it sounds like you're going form a 12V to a 12V positive. Quote Link to comment Share on other sites More sharing options...
24OZ Posted December 21, 2008 Author Share Posted December 21, 2008 Sorry if this is a nooby question but what is the difference between a 12V and a 12V +? Quote Link to comment Share on other sites More sharing options...
24OZ Posted December 21, 2008 Author Share Posted December 21, 2008 By the way, I never made myself clear in the first post. My test light isnt a normal one with just a bulb in it, it has a bulb and a battery. One end is a pointer and the other a crocodile clip, when you touch the pointer with the crocodile clip the light comes on, which means a circuit is present. here is a crude diagram of what I did, now shouldnt the light have come on? Thank you Quote Link to comment Share on other sites More sharing options...
naviathan Posted December 22, 2008 Share Posted December 22, 2008 Try it between the switched 12V and the injector 12V. Quote Link to comment Share on other sites More sharing options...
24OZ Posted December 22, 2008 Author Share Posted December 22, 2008 I did and it still did not light up. Quote Link to comment Share on other sites More sharing options...
naviathan Posted December 22, 2008 Share Posted December 22, 2008 That test light is a continuity checker. There's probably a relay between the inputs and the injector outputs that breaks the continuity. Quote Link to comment Share on other sites More sharing options...
24OZ Posted December 22, 2008 Author Share Posted December 22, 2008 That would make sense. Thanks Naviathan. While I'm here I have a question on the 12V+ source. The megamanual says "make sure you have a 12V supply in both the run and crank positions". Can I just take a 12V+ from the battery and hook it straight to the round 12V + connector on the relay board? Thanks for your patience guys, I really am not a wiring guy. Quote Link to comment Share on other sites More sharing options...
naviathan Posted December 22, 2008 Share Posted December 22, 2008 No no. What the manual is referring to is the switched 12V line. You need to chose a line coming off the ignition switch that is off when the ignition is off and powered in BOTH the RUN position and the START position of the ignition switch. If you don't and it shuts off when the switch is turned to start obviously your fuel injection will lose power and not start. There are several wires off the ignition; Only one will be hot in both positions because most accessories aren't necessary to start the car. Quote Link to comment Share on other sites More sharing options...
mobythevan Posted December 22, 2008 Share Posted December 22, 2008 The relay board requires 3 wires to power everything correctly, you will see them labeled something like 12v, 12v switched, ground. You can connect the battery directly to 12v. Connect ground appropriately. Connect a wire that has power during running and cranking to switched 12v. After that is hooked up then when you turn the key on one of the relays will provide fused battery power to the 12v injector terminal and your tester light should work to see it. Quote Link to comment Share on other sites More sharing options...
24OZ Posted December 22, 2008 Author Share Posted December 22, 2008 The relay board requires 3 wires to power everything correctly, you will see them labeled something like 12v, 12v switched, ground. You can connect the battery directly to 12v. Connect ground appropriately. Connect a wire that has power during running and cranking to switched 12v. After that is hooked up then when you turn the key on one of the relays will provide fused battery power to the 12v injector terminal and your tester light should work to see it. Thanks Moby. Quote Link to comment Share on other sites More sharing options...
zbigtim Posted December 22, 2008 Share Posted December 22, 2008 You can't use a continuity checker for voltage. You will need a volt meter or a voltage test light... Quote Link to comment Share on other sites More sharing options...
naviathan Posted December 22, 2008 Share Posted December 22, 2008 You can't use a continuity checker for voltage. You will need a volt meter or a voltage test light... Ugh...He's not checking voltage, he's checking continuity through the relay. Quote Link to comment Share on other sites More sharing options...
zbigtim Posted December 23, 2008 Share Posted December 23, 2008 Ugh...He's not checking voltage, he's checking continuity through the relay. I see that now... Sorry, my bad! Quote Link to comment Share on other sites More sharing options...
naviathan Posted December 23, 2008 Share Posted December 23, 2008 Sorry, it's just irritating when people chime in with something that's already been covered further up the same thread. If he had the wrong tool for the job I think I would have identified it for him. Quote Link to comment Share on other sites More sharing options...
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