Forum:
Hi Again,
I have a fourtrak 1998 2.8d
The passenger side headlamp is only working on main ( high ) beam - I have tried replacing the bulb but this makes no difference - I have now tested the old bulb also off the car and it is working fine.
Anyone have any ideas what the problem might be 
thanks in advance
Mark
Light Work
Check the obvious first, is it the fuse for the appropriate circuit, they contain a seperate fuse for main beam and high beam.
If these are both ok, it is a case of checking for voltage at the bulb connector, if voltage is there then it is a rusty of faulty connection between the bulb and connector.
If no voltage is present, it is a case of tracing the wiring back, and checking which section of the wiring loom is faulty. Wiring usually breaks or corrodes just behind, or inside the connector, so one method of testing is to insert a pin through the insulation of the appropriate wire a few inches behind the connector and rechecking for voltage.
Three lugs on a light bulb.
Check if you fitted the bulbs fitment of three lugs the correct way around. Get it 180degree out and one of the elements will not light.
Also use a meter across the connectors and test for a circuit. No circuit = follow it back fuse, switch and earth.