connecting logic gates
It's pretty "brave" to connect (what I think are) 16V (18V abs max) logic chips directly to a 12V automotive supply. Automotive standards call for survival of transients much larger than that. At least you have a diode to prevent negative transients from zapping things. 

Please give manufacturer part numbers not distributor numbers. 

The NAND will get powered by the protection diodes whenever either input is high. 

There is no current limiting- it's not for sure the wimpy little BAV21 diodes will survive charging the 10uF caps, nor is it clear what exactly discharges them. 

There should be a series resistor on the SSR LED to limit the current. 



I agree with @brhans comment- just stick a W04M in there and be done with it. 









simulate this circuit &ndash; Schematic created using CircuitLab