low beams out

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May 22, 2007
new orleans
87 fj60 - PO installed an H4 headlight upgrade - new harness with two bosch relays, install looks tight. The low beams are out - I have power to the relay, i hear the relay click, and when I "jump" the lamp the lights come on. The high beams do work. One relay seems to work the hi beams and the other the low beams. Swapping relays makes no change.

Also - does the upgrade bypass the dash fuse box? I get a 12v read from one fuse but not the other - ie. they don't seem to be sided as indicated LH, RH. I pull the 10 amp fuse at the upper left and all the lights go out (both hi). I pull the one below it and nothing happens (this one shows no juice - related??)

My low beams went out when the multiswitch on the column went bad. I might have been able to clean it up real well (search for the technique), but I just got a new one for a decent price. Works great now.
My bet,based on past exp. switch on column. MIke
Personally ID go new ,esp. with your light upgrades. A 20 year old switch, not me. MIke
I had a similar problem. Aftermarket wiring harness, low beams worked when jumped only, not the "normal" way.

Took apart the multi-switch, cleaned, etc. Didn't fix the problem.

Pulled hair out.

Posted on mud...one suggestion was "lost ground."

Plugged aftermarket wiring harness into other side of OEM harness, all was fixed.

OEM harness will allow a ground connection to be shared between the DS and PS lamps, but the aftermarket harness won't allow this. In older trucks, you can (and do) loose grounds.
thanks ski - I was thinking of chasing down the ground. - locked 4.10's? can you turn on pavement without squealing tires?

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