@#2
The reason I suggest replacing the battery cables is based on 5+ decades of having to deal with 'no start' issues and 'degraded communications'.
Seems a lot of guys need to replace the battery, 5-10-15 years old, never ever consider the cables.
That means the engine has been started 100s if not 1000s of times. Each start puts a lot of stress on those cables, passing 100s of amps through them, ANY resistance('bad' connection ) creates heat and strands flex a bit. Add to that water( not pure either) and it'll wick up the strands. Over time copper corrodes.That green patina on sculptures and expensive gutters may be pretty BUT is nasty for wires !! Typical battery connections have lead, steel, brass, nickel and of course copper. Any water or moisture creates a 'battery' due to them being dissimilar so corrosion starts, slow at first but it is happening.
As for testing cables, no regular DMM, DVM,' meter' can actually test battery cables. Most are good for maybe .1 of an ohm IF the user remembers to account for the 'lead resistance'. When you need to pass 100s of amp, .01 ohm 'loss' is important. Push 100 A through .01 ohms and you lose 100 watts of power. Ever touch a lit 100 watt lightbulb ? That heat has to go somewhere...
We've seen posts here where battery was replaced, starter was replaced, relays and FINALLY new cables were installed and rr-rrr-vroom ! We've also seen pictures of those 'clamp on ' battery posts with obvious external corrosion on 'no start' posts.
Do new cables always solve the problem, no ,but I'm sure most here would rather replace $40 worth of cables than fork out $400 for a new starter that wasn't really needed.