My fan does not work on any of the four speed settings, i checked fuses and they are good, what else could be causing this problem?

Usa car, not Holden made. my 2nd post here same car same issue.
heater blower, motor.
dead,
hot wire blower, work now?
got 12vdc to blower power pins on HIGH?
yes, no.
this is first way before ripping dash asunder...
the motor is DC, and not AC.

the job here is to see.
1: lost power, Fuse, wires. learn to use a voltmeter, its easy.
2: controls failing?
3: motor dead.
in that order. or waste 8hours, labor for nothing.

now ill read the schematic for you, on alldata.com
ok the real hit list not BS, or bsa

1: cb15 blown, marked, electr ig, in dash box.
2:EB16 main 100am fuse blown that feeds
3: A/C heater relay bad.
4: now the tricky part, isuzu BS to the max, the run 2 fuses in parallel now. here, called EB5 and 6 (EB= engine bay box)
then power goes to motor +
5:motor minus wire goes to the switch fuse. and on high goes to ground like a shot.
seen here. 5 fuses total, a world record for sorts.
warning it love to blow fuse 5 or 6, and if you try to run it on one fuse the other glow BAM pronto. real junk here... by isuzu.
15a + 15a fuse = 30amps this silly way, and issues.

got 12vdc to top pin on motor? above.
got 12vdc to bottom pin of motor if yes, the switch is failing
remove blower resist and check all paths for 0 ohms.
if not ,zero its bad and for sure that thermfuse there.