Hot answers tagged wiring
Sounds like a bad ground. I would install new ground wires. Get some heavy cable (like 2-6 gauge multi strand) and solder some lugs onto it. Wire the battery to body, then that same point on the body to the block. Make sure all spots are nice and clean. Be sure to give yourself some slack
In general silicone gease applied to the parts before and after assembly is a good way to go. It will be pushed out of the way where you have tight metal to metal contact so it won't cause electrical connection problems. It won't crack up if things move slightly and it won't stop you dismantling and reassembling things if you need to.
The power socket has a simple two cavity connector. It will most likely have #2 female spade connectors. Connect a new device with male spade connectors after first verifying polarity. I would not look for a matching connector, finding one is unlikely. I just take them apart and make a plan. Drawing of power connector. It may not matter to your plans ...
Your car Audio should work well in your garage .Mine has been running for 17 years now .The 12 V DC power supply needs to be rated for the job as others have commented .If you use a switchmode power supply which is more common these days you may get noisey radio reception due to the crud that these supplies put out .Placing the Antenna on the roof will ...
You can repin the connector or most auto parts stores will sell a replacement harness connector that you can crimp or solder on. ECH LS6235 The xB takes a 9003 bulb.
As stated before by Pete, I'd also recommend cutting or splicing the existing wires and adding your connections there. It'd be a lot easier and at times cheaper to do this as well. I've done multiple mods on many cars, and have done this method and not one has failed. As long as you do your testing in Phases, e.g. connect two wires, test all is working then ...
You could just strip, solder and heatshrink the relevant cables together - should just be two, I'd guess. Quicker, easier, and less likely to break than trying to match the plug on the back of the 12v outlet. If you don't feel confident doing it yourself, an autoelectrician wouldn't take longer than 15minutes if the cables were all accessible and you drove ...
You can buy a spray can of undercoating and spray your connection area with that after your connection is made. Paint works too, but undercoating is somewhat flexible and won't crack like paint will if the connection is subject to any flexing.
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