Volvo VNL ISX troubles with starter or other electrical issue?

You do not need an ammeter to test it, a DVOM test for voltage drop is all you need. A poor ground connection is always my first suspicion with an electrical issue such as yours, grounds are most often at fault and are much more subject to corrosion and getting loose as they are frequently in less, or unprotected areas and exposed to the elements when compared to power connections. Poor ground = high resistance = poor current flow = high heat and increased resistance and so on, the area that gets the heat is the area of the most resistance.

 

Make sure it is capable of both AC/DC 600 amps... most cheap ones only do AC..

.... Philip

 

400-600amps depending on how compression is..

>600a bad starter,
<400a bad battery, connections, cables, bad commutator, hung brush, bad solenoid... Needs additional investigation..

 

Now I have wasted all 30 yrs as an electrical/mechanical engineer.... Mind you most of my work was non critical like Nuclear power generation and fire control.
You can have voltage with little or no amperage (until you load the circuit),

.... Philip

 

Which is why the test is performed while energizing the circuit/cranking the starter, Einstein! Do not assume you know everything and no one else knows anything!

10.5 volts minimum, RSQ20. Connect the DVOM at the starter connection+ and known good ground.

 

It does not need to spin, just energized....

.... Philip