Re: Battery help:Why are there so many cables?
You would best be served tracing out where those wires go and putting labels on them as suggested... Since it has a crimp on connector with yellow insulation the black wire could be anything...
That is a quite heavy gauge wire for a radio memory wire imo but people wire things in strange ways! with whatever color is handy!
I get more calls in the spring when people put their batteries back in their boats needing help because their radio won't work. Most of the time it ends up being a inline fuse or circuit breaker.
*Warning* Don't randomly check wires for continuity, you should turn off/disconnect the battery before checking continuity otherwise you may damage your meter.
First lets see if the radio is grounded:
Grab your trusty multimeter and set it to 1x Ohms (the greek omega symbol)
Put one end of the probe on a known ground (such as a buss bar or ground distribution panel, or run a long lead back to the ground on the battery)
Then check the black wire on your radio.. The meter should read ZERO indicating a closed circuit, this means your ground is OK.
If it doesn't read zero the radio isn't grounded.
Then change your meter to DC Voltage and see if you have any power on the yellow wire (normally the memory wire) turn the radio switch on if so equipped and check again. (Some people wire them so they don't retain the station memory.) While the switch is on check the red wire, it should show 12+ volts.
If you have ground and there is 12vdc power on both yellow & red check to see if there is a fuse in the back of the radio, if this fuse is blown replace it if not your radio is the problem.
If the yellow wire has no voltage then the wire that keeps its memory is no longer connected or has a blown fuse. Look first for fuses & circuit breakers then lets move on to the wires in question that aren't attached to your battery:
Starting with the black wire with the yellow connector that isn't connected to the battery set your meter to DC Voltage then touch the red probe to the connector and the black probe to ground on the battery. It should read zero, if not this wire has voltage on it and shouldn't be connected here anyways.
Then move the black probe to the positive terminal of the battery again it should read zero, if it reads -12volts then the wire in question is grounded.
Now we should have deduced that the wire in question isn't connected to anything lets set our meter back to 1x ohms.. Connect a long wire to the ring terminal and go back to the back of the radio... Touch one probe to the yellow wire and the other to the wire you just extended, if it reads Zero then you have found the end of the yellow wire. You should then label it as radio memory, or wrap the end of the wire in RED tape to prevent future problems.
You can repeat this process for the red wires with alligator clips but from the picture they almost look like they are nothing but test leads!! Are you sure the red wires with the clips are actually connected to anything?? If not be sure to save them because they will come in real handy next time you need to trace a wire!