High beam, inside, XJ6C, 1977 not working

For a 1977 xj6c with a chevy conversion: Outside headlamps, L & R, work–good brights and dims. But the inside headlamps, on high beam, only the passenger ® side works. the driver’s side (L) doesn’t. Just replaced the dimmer relay. That made everything work OK, THEN the next time I started the car, same old problem, the outside L & R lights went on per the switch, both low and high, but on high beam only the inside light on the passenger lit up, the driver’s stayed dark.

Is something in the relay burning out?


Check your grounds for that light. They are just a bullet connector from memory and can give trouble, BTDT.

Best bet.
Grounds often work for a while until they don’t, then, the next day, they work… etc. also BTDT.

If the relay does not have individual blue white wires for each inner lamp - I don’t think it does - it is fine! The wiring will however have a bullet connector where it splits up and from there on to ground it is interesting.

Have you checked the bulb, Lawrence? An obvious ‘blown’ possibility…:slight_smile:

The relay is innocent - as David says; the relay operates outer ‘high beam’ and inner lamps with high beam selected. And the outer ‘low beam’ in low beam setting - the outer lamps’ bulbs have two filaments, of curse…

Inner bulb should be checked before searching for other possible faults…

As an aside; there are 4 light fuses; ‘left’ high (outer and inner), ‘right’ high (outer and inner), ‘left’ low and ‘right’ low (outer’s only). As ‘left’ outer high works; the relay and the fuse itself are innocent, but you may check this fuse holder connection - in addition to ground and lead connections, as suggested.

xj6 85 Sov Europe (UK/NZ)

Robin, David, and Frank,

I fiddled and made it worse. Outer high beams work, outer low beams now dark. As for the inner beams the R one works, L remains the same, nada. Near the end, I discovered that one fuse, 3rd from the left (maybe fourth) was quite loose. I needed more time–and cooler air!–to do anything. I did jiggle the wires that connect to the relay. Thought maybe tomorrow I would fix the fuse slot and ground the black wire leading to the inner L (the other wire to the inner L is blue/white). Also the inner L bulb is new and good.


keep cool;-) and follow the wiring - it’ll work out! This part of “electrickery” © Carl Hutchins is just the training ground. Have you got the correct wiring diagram for your car? It is quite helpful. I take it your coupé is wired just as my SII sedan; so I put in a part of my wiring diagram

231 is the headlamp relay you find front at the left side of the radiator upper cross brace. It is powered from the ignition lock (operating circuit blue at 56) and from the battery (operated circuit brown at 81a). 56b takes power to the low beam outer headlight through the fuses located on top of the radiator cross brace. If power is applied through the high beam stalk switch the relay will remove power from the low beam circuit and power the high beam filaments of the outer head lights plus the inner head light. All of the headlights are grounded by their housing, but do have independent black wire grounds. They are connected to the vertical bars left and right of the radiator and often rust away.

Unless a PO has disturbed the system - some people like to drive with four headlights all the time - you are fine as long as both outer headlights are on with the switch at “high” and the high beams come on with the operation of the stalk switch. As Frank pointed out with your fault list the switches, the relay and the fuses are proven innocent. The fiddle factor has most likely affected your grounds. I bet all of your grounds are supplied only by the mounting of the buckets and the black wires are lost. Track them and replace the grounds and you’ll have wonderful light - well, depending on where you are located you might think about a 7" H4 conversion - but, apart from this, everything will be fine.

Good luck


75 XJ6L 4.2 auto (UK spec)

As the outer ‘high’ is working; power feed through fuse to inner (high) is likely OK - they are connected together at the fuse holder…

You may jumpwire between lamp bulb holder and ground to positively verify a ground fault - but checking ground connection ight be equally useful…:slight_smile:

The two inner fuses of the holder are indeed for the high beams - the two outer ones for ‘low’ beams; ‘right’ and ‘left’ respectively. If both outer ‘low’ beams are now out; your fiddling is likely the cause - so I hope you remeber what you did…:slight_smile:

xj6 85 Sov Europe (UK/NZ)

Jochen‘s diagram has all you need. If the fuses are in the order of the diagram then there is one for each low beam and then one for right side highs and one for left side highs.
U is blue; r red, w white tracers.

Clean all the fuses well and maybe try new ones, and ground all black wires carefully. If the low beams stay dark you might have accidentally disconnected UR or U at the relay.