Forum Discussion
wolfe10
Oct 28, 2013Explorer
Easiest to start at the alternator. Trace the large gauge (usually red)wire from the alternator B+ and it will lead you right to it.
Alternately, you can trace from the batteries, but there are lots of other wires from that end.
To test (assuming this is a diode-based isolator-- will have fins to keep it cool):
With engine off, check voltage at each of the large lugs. Each outer lug will reflect the voltage at that battery bank. The lug that goes to the alternator will have zero.
Start the engine, put to high idle (like around 1000 RPM) and recheck voltage. Should be around 14 at the outer lugs and around 14.7 at the B+ lug.
Alternately, you can trace from the batteries, but there are lots of other wires from that end.
To test (assuming this is a diode-based isolator-- will have fins to keep it cool):
With engine off, check voltage at each of the large lugs. Each outer lug will reflect the voltage at that battery bank. The lug that goes to the alternator will have zero.
Start the engine, put to high idle (like around 1000 RPM) and recheck voltage. Should be around 14 at the outer lugs and around 14.7 at the B+ lug.
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