1. Swap your switch from power to ground. Do not put amperage loads on your switches, even if they are rated for it. That includes the triggers for the relay: just send ground to the baffle terminator, not the power supply. Power can come directly from the positive bus range of the battery.
2. For cars with digital components, use separate ‘dirty’ and ‘clean’ ground bus and power supplies. Digital components like ECU etc don’t like noise from fan motor, fuel pump, water pump etc. They also don’t like electrical pulses caused by switching on and off relays and solenoid coils. If you have a HEI distributor or high power digital igniter on a carburetor car, it’s probably wise to isolate that power from ground.
3. Use a grounded bus strip directly connected to the negative (sad) terminal of the battery to ground. Don’t ground everything to the body. That is too bad. This also goes with #1. If you are powering your switch and just grounding everything to the body… yes it works but does it work?
4. Avoid damaging sensitive things by voltage spikes by placing a diode across the anode and ground. These are called ‘flyback diodes’ and you should keep voltage spikes from burning the components. Most modern electronics will have diodes inside, however, it’s less expensive and better.
5. Use a good baffle connector. Don’t just thread the wire through the holes in the firewall.
Posted by Brian Madigan
