The right hand headlight on my Haynes is brighter than the left, it's difficult to tell bur it seems just the dip beam, the headlamp bulbs are the same and I swopped them over to make sure it wasn't anything silly like a faulty bulb. The wiring loom/fuse box/relays are from the Sierra donor car.0

you may find the earth is in the wrong place on the dim headlight  or indeed a bad earth

Edited March 16, 20224 yr by tractor

Not very likely but some Sierra's had a dim/dip setting for lights. depends on if your builder/wire-man used this in a straight swop.

If the Sierra loom was from a model up to 1987, then both dip and main use the same earth. I think that you probably have a sealed beam unit ? with the three spade connectors, in which case make sure that the contacts of the spades are nice and clean however since you swapped them then they probably have scraped cleaner by now. If its a bulb holder then youcan try swapping the holders?. The Main beam is a white wire the RHS one runs from fuse 15, the dip is a yellow wire, the RHS runs from fuse 17. Check the contacts on either side of the fuse holders. The LHS fuses are 14 and 16 resp, so you could measure the resistances from the fuse to the bulb connector on each side to see how they compare.

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Sorted, as suspected/suggested a bad earth, had to go all the way to the bulb holder itself though, simply soldered in a new earth cable. Thanks for the help chaps.

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