[IanH]

well I shouldn't hold your breath waiting for an answer here.
1) you have what i assume is a (N15) RHD
2) its diesel and they aren't sold in the USA, so you have to rely on our few UK, Asia, NZ and Aussie members
3) this is a B14 forum, ie LHD non Diesel crowd

hopefully someone will prove me wrong !!

My thoughts.
1) fuel filter / fuel pump
2) Air temp sensor
However i haven't worked on a diesel since I worked on forklifts at Ford UK.

On the High beam light, poor ground on the cluster, take out plugs (3) and clean with contact cleaner ( don't use anything solid to clean, fluid only.
Bad ground on LH headlight, are you sure that the headlights light up correctly, not out or dim ?
This is from the B14 FSM, your headlight circuit supplying power the warning light may be different.

 

[IanH]

Well as you can see below the voltage for the indicator light comes from one headlight circuit.

 

[IanH]

what happens when you unplug one headlight at a time ?

 

[IanH]

With the headlight connected.
check the voltage on the ground connection on the headlight at the head light.
you say the voltage on the high beam terminal is correct ?
when dipped you get 0 V on the high beam terminal correct ?
when on high what is the voltage on the dipped terminal.
If you cant get a metal contact without unpluging it put a slit in the wire jacket somewhere where you can tape over it when you are done.