Hi all, My 1982 XJS seams to have a headlight issues. The right( passenger side) low beam is out.I tried the obvious and changed the lamp but still nothing. If I put the high beams on both lamps light but both lamps on the driver side go off. Any thoughts on this would be greatly appreciated.

 

Go to the headlight fuse box, check and remove the fuses, and clean the fuse end caps and the little clips that they snap into. If that doesn't help then unplug & clean all the bullet connectors nested under the headlight fuse box. Also, remove/check/clean/tighten the two headlight ground points. These are at each end of the radiator upper mounting panel.

Cheers
DD

 

Thanks Doug, I'll start there. Is that common for it to turn off the opposite side when the highs are on? Both, high and low on the right come on when the highs are on but the left, which normally work fine, shut off when the highs are tuned on.

 

Only the high beam element in the H4 light should be lit when high beams are on, and only the low beam when the low beams are on. If both elements are lit on the bulb when the high beams are on, you likely have a short somewhere between the live feeds in the wires from the relay to the actual light, or in the socket that contacts the bulb connectors.

If you pull the bulb socket off the bulb and use a test light or a meter to test the high beam and the low beam contacts and see which is live when, you can work back up the wires to the relay from there, following Doug's prescriptions.

For example, a broken low beam feed wire that has melted downstream of the break into the high beam feed wire would give you those symptoms.
Greg