Headlights work on "high beam" setting only.

[reubj]

I did the relay harness install several years ago and worked great. A few years after that the passenger side light went very dim. A few months ago neither light will work on the low beam setting. High beams work fine, except the dim passenger side.

Point me in the right direction.

Thanks!

1989 MJ Renix

[AnotherOldJeepGuy]

If you have a volt meter you can check the voltage at the bulb connector with the bulb removed.  On my harness there are blue, white and black wires at the bulb connector.  The black is ground.  I don't remember if white is high and blue is low, or the other way around.  But with high beam selected (the setting that is working) one of these will be 12V and the other be less than 1 volt.  Switch to low beam and which every was 12V at high will drop, and the other should read 12V.  If you don't find 12V at the other wire when low is selected you know that the problem is in the wiring or the switch or the relay that has that same color wire.  If on the other hand you do get 12V on the other color when you switch into low beam position, that would suggest the bulb itself has failed and you need a new bulb.  If you are lucky that is the problem and the fix, it will take more debug to figure out if the problem is the relay or the switch or the wiring itself if it is not the bulb.

[fiatslug87]

Swap the two relays and see what happens, easy to do without removing anything.

[reubj]

Thank you for the replies.

[AnotherOldJeepGuy]

1 hour ago, fiatslug87 said:

Swap the two relays and see what happens, easy to do without removing anything.

Definitely the first test!  I didn't realize the relays were socketed.

[reubj]

It looks like one of the relays is bad but I still get low voltage on the passenger side.

I'm going to take the easy way out and install a new harness.

[AnotherOldJeepGuy]

Good luck!