1999 wh holden statesman turn signal wont flash at all just stays on

every possibility that it will as the statesman is just a glorified commodore any way
GM holden used as many common parts as possible to keep prices down

with bodywork either need the equipment that a body shop carries torches-frame racks-hammers dollies[for small stuff]-and unibody tower will cause other areas to be bent =or take to a body shop for estimate

More than likely the tiny electric motor that moves the speedo needle has failed, very common issue on GM cars and trucks.

I've just put L67 vacuum lines into "images" on bing and got all sorts of pictures, start there?

could be two thingbs the ecu might have gone faulty or the code in the remote or th furl pump might have died

if its loud knocking noise at idle from front area of motor possibly crank pulley has separated from rubber.
when motor is not running can you grab the serpentine belt and move it along rotate it from left to right side of vehicle until it clunks to a stop which is the saftey lugs on the inside of the crank pulley, turning the pulleys?
if so the crank shaft balancer needs replacing
if you cant turn belt over by hand its ok and could be an internal motor issue, big end or camshaft bearing failure were the other common faults

Follow the given link, maybe you get something useful.
2005 Holden Statesman WL 6 Cyl Workshop Service Repair Manual

you shold check your battery first
__________
x-vci tool

We do not have wiring diagrams here at fixya, sorry.

I would think the heater blower motor is shorted.