I've never seen wuauclt /? display anything useful.

However, if you want to initialize Windows Update to install updates on a client, use wuauclt /detectnow.

The "automatic detection frequency" on clients node are 1 hour. can i force the client to detect the newly approved update without waiting for one hour.

I tried to use wuauclt.exe /detectnow but it did not help.

Did you use both /detectnow and /r /reportnow

wuauclt /?, wuauclt /help, wuauclt /h does not work. Where is documentation for /detectnow?

I Found that I had to do both

wuauclt /a /detectnow

and then

wuauclt /r

for an update to occur

net stop wuauserv
REG DELETE "HKLM\Software\Microsoft\Windows\CurrentVersion\WindowsUpdate\Auto Update" /v LastWaitTimeout /f
REG DELETE "HKLM\Software\Microsoft\Windows\CurrentVersion\WindowsUpdate\Auto Update" /v DetectionStartTime /f
Reg Delete "HKLM\Software\Microsoft\Windows\CurrentVersion\WindowsUpdate\Auto Update" /v NextDetectionTime /f
net start wuauserv
wuauclt /detectnow