90 lights help

If there is no power going into the switch, then no matter what position you turn it to you will not get any power out.

To check the switch with a multimeter.
Now with the multimeter in the continuity position ( which normally looks like a diode symbol, if you put the red and black probes contact together then the tester will beep and show 0000 on the screen )
Place the red test lead on the supply, and flick the switch, move the black probe to the other contacts, one of them should beep. when thi happens flick the switch off. and it should stop beeping. check and note which terminal does what.

Question is, why do you not have power going to the switch?

OK cheers will go try that, and that's the big question which I can't work out myself, have power St fuse and traced the wires as best as I can but can't find a fault I them

If you have traced the wire to the switch , have you checked the continuity? same procedure as above, probe in to connection at start of wire and other probe into other end of wire at a connection point. just in case you have a broken wire.

Cheers

Yea checked the wire and can't find fault there

If you have power at both sides of the dipped beam fuse, you should have power to the switch. If not, there's a fault in the wiring, possibly the plug at the steering column?

It's common to have power at one side of the fuse, but not the other - due to corroded fuse terminals.

The symptoms you describe are very like what happens when the switch is defective. You can flash the headlights but they won't stay switched on. The fact that they will flash suggests that (most of) the wiring is OK. Are you sure that none of the terminals on the switch is live? With the engine running? Scratch your probe around on the terminals just to make sure it's not a bit of oxidation making them appear dead.

I think the flash gets its supply from a different place than 'normal' headlights

Have you checked the 30 amp fuse in the engine compartment, power is fed direct from the battery through this fuse to the brown wire on the light switch. if you have no power at the switch then it is probably blown. Did I say its in the engine compartment and not the normal fuse box in front of the gear stick?

Fuse box is on the bulkhead on the left side of the heater box (as you look at it)

Well?

Also if you are checking for continuity disconnect the vehicle battery or you will probably be looking for a new meter.

Ok, you are saying there is no power coming to the switch from the fuse. In the case of the sidelights, there should be power even with the ignition off and the key out, which suggests the wiring is faulty.
Run a flying lead (a spare bit of wire) from the fuse to the switch and try the sidelights again. I don't have a 300tdi wiring diagram to hand, but I don't believe there is a relay in the middle for the sidelights.

Kwakerman said:

I think the flash gets its supply from a different place than 'normal' headlights

Click to expand...

Yes, that's what I mean. If you can flash the headlights with the indicator stalk but not the usual headlight switch then it tends to be the headlight switch at fault in my experience. Or possibly the wiring but it's usually the switch.