XJ6 & XJ12 Series I, II & III 1968-1992

headlight problems highbeam/lowbeam

Old 03-25-2009, 11:43 PM
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The headlight relay for your XJ6 is just forward of, and slightly below, the brake master cylinder (assuming this is a U.S. left hand drive car). It is a large rectangular silver relay, Hella manufacture. If you look on the inboard relay connections, you will see a pair of blue/ red wires (low beam), a pair of blue/ white wires (high beam), and a blue wire (feed from headlight switch). In your case, if you swap the blue/ red and the blue/ white connections, you should have all four highbeams... and darkness when you hit the flash switch and operate the relay, no lowbeams. That will confirm that the relay is bad: no power to terminal 56a in either position, but fuses and lamps all in proper working order.

If that's the case, and you want a good used original equipment relay, please click on my screen name above and send me a private message.

If the relay tests OK and you still have only low beams, you'll need to do some checking with a testlight. Doug Dwyer posted some troubleshooting tests for these circuits about two months ago, I didn't read the post but he is a credible source and the fuse and bullet connector problems are probably discussed in detail there.
Old 03-26-2009, 05:37 AM
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which Fuses have you checked? the ones in the engine compartment located near the brown coolant tank?

there are 5 fuses there in the little fuse box: 1 for each headlamp, and the fifth is for the auxiliary cooling fan located under the front bumper.

Old 03-26-2009, 09:29 PM
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JTO and Jose have given you plenty to go on but here's the checklist that was mentioned


Old 03-27-2009, 07:36 AM
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The headlight fuse box is on the left side, near the coolant tank, as Jose said. The plastic cover is, oh, maybe 1.25" x 3.5". You can't miss it.

Not sure about the other fuse you mentioned. The horn fuse is in an in-line fuse holder approximately above the battery...but that's a long way from center. Jaguar did use a lot of mysteriously placed in-line fuses, though.

Old 06-17-2009, 01:16 PM
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Default Relay

I think I replaced my relay long time ago and my headlights still don't work. The link given by Doug seems to be the best way to start in troubleshooting the problem. When I get home, I will have to start cleaning contacts and may change fuses along the way.
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