em3emcee Posted January 17, 2013 Report Share Posted January 17, 2013 I'm new to this forum and automotive wiring in general but I'd like to ask for assistance in wiring up some standard SPDT/Bosch 30A relays. For reference, this is for a 1988 BMW M3 which I'll be using a V88 to have all my fun. Here's what I've come up with for my install: Can anybody chime in here and offer help? The EVAP PURGE RELAY will be sending an output to close the purge valve (I think) and I'll figure out how to do that at a later date. Thanks. Quote Link to comment Share on other sites More sharing options...
Dave Kriedeman Posted January 18, 2013 Report Share Posted January 18, 2013 I would apply 12 v positive to all of your relays pin 30 via a fused connection to the battery or common positive rail (bus bar) or insulated terminal post. If you use Bosch 5 pin relays which are not change over style, eg: have 2 pin 87's not 87 and 87a This would simplify your relay assembally wiring. Connecting your 2 pin 85 's for the purge relay and fuel pump relay directly to the main relay pin 87's Regards Dave. Quote Link to comment Share on other sites More sharing options...
JCE Posted January 18, 2013 Report Share Posted January 18, 2013 My system is wired something like this....Makes fault tracing easier when every component has its own relay+fuse. I also have one relay for aux equipment: cd player, dash gauges etc... Quote Link to comment Share on other sites More sharing options...
JCE Posted January 18, 2013 Report Share Posted January 18, 2013 Oh yea and one other thing: pin 85 is Ground/negative and 86 is ignition/positive. Normal relays will work both ways(85-, 86+ or 85+, 86-), but some relays have a diode inside and if connected wrong, it will shortcut your ignition switch to ground and blow the fuse. Quote Link to comment Share on other sites More sharing options...
Dave Kriedeman Posted January 19, 2013 Report Share Posted January 19, 2013 JCE your relay schematics are spot on. Regards Dave. Quote Link to comment Share on other sites More sharing options...
Ducie54 Posted January 29, 2013 Report Share Posted January 29, 2013 Would it be ideal to run another Aux relay for items such as LC1, vvl solenoids, display dash, Knock block and boost solenoid or could I just run it off pin 87 from main relay? Cheers Quote Link to comment Share on other sites More sharing options...
Simon Posted January 30, 2013 Report Share Posted January 30, 2013 You can of course have more relays. It really comes down to the current load on each relay. No point having a massive amount of relays all supplying a couple of amps each. Quote Link to comment Share on other sites More sharing options...
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