I just did a solenoid rewire for my headlights. I used an old bulb to access the power, Cutting the bulb off the socket and soldering wires to the leads. I also took a second bulb and just cut the bulb out , filling the socket with silicone to keep water out of the plug.
Two relays one hooked up to Low and one to high with both returning to the one neutral. I did a quick line drawing of the set up.
My problem is when I switch on the high beams. They seem to keep both sets on for a random amount of time. It's worse when the fog lights are on too. I can force the reset by turning the switch off and on again. Also some times the high beam indicator on the dash will stay dimly lit.
Is there a required resistance to make the lights function? Since the relays draw so little power, do I have to add some resistors to get it to work right?

Thanks for any help.

 

It could be that your relays contain a diode that should prevent backfeeding.
As a first step I would try to change the polarity on the relays where they get fed from the stock plug.
Start by reversing the leads on the low beam relay and test.
(Going through all permutations..)
low as is high as is = problem
low changed high as is = ?
low changed high changed =?
low as is high changed =?

Please report back with the results.

 

Does this truck have Sport headlamps with 4 bulbs? If so, be aware that the outer bulbs are meant to be 9007 bulbs, and the inner bulbs are meant to be 9004 bulbs. The problem is that while the same connector will physically plug into either bulb, the 9004 and 9007 are wired differently from each other, and will not work properly unless your connector is wired properly for that bulb. For example, one of them uses the center wire as the ground, and the other uses one of the end wires as ground. If not wired in this fashion, you could have backfeeding that can illuminate the high beam indicator, and other stuff. I might have a diagram here somewhere, hang on.

 

here it is, hope it helps

 

This is how mine is wired.

 

It didn't originally have sport headlights. I did a swap out from LMC.
Truck Parts and Truck Accessories
They were much brighter than the cloudy OEMs that were on it. I just wanted a little more so I swapped the H1 55W bulbs with 100W. I thought they were drawing too much on the crappy stock wiring so before the whole front end went up in flames I did the relay mod. They are absolutely 100% brighter. Almost new car HID bright.

I pulled the relays and neither have diodes (thanks for the idea Alpine)

Cougar, I didn't intend on the Quad light mod but otherwise mine looks similar. I noticed the plugs have one Positive lead and two negative ones. It seems counter intuitive to me but I had heard something about a negative switched system in these vehicles. I'm thinking that is probably my issue. It's either that or I have to get another pair of relays and connect it to the other side, instead of running all off of one side plug.

 

The head lights and fog lights on the 2nd gens are negative switched at least on the 00, 01, and 02's and would be surprised if the 99s and 98.5 at least aren't the same if not back to 94..

 

Do you have a daytime running light module in your truck?
(should be on the driver side fender under the hood)

 

no DRLs but I wired the LED halos around the projectors to a switched circuit so I do have daytime running lights. But they are completely isolated from the headlight circuit.
It definitely is in the stock switching circuit because using the fog lights messes things up worse.