1987 headlight relay wiring

[xs-style]

When I did the headlight relays on my 78, I bought the lmc h4 harness. It was well labled, even though with a single headlight setup, it didn't really have to be
Everything was straight forward.

Now I have this k5 so I ordered a generic harness off eBay. This time I could have used instructions lol but I'm sure you guys can set me straight.

My first picture there should be the two relay connections and two grounds.

The second is my harness connection and the passenger side headlight plugs. My question is this... Is the plug with the yellow wire ment for the low beam light?

[xs-style]

Does it plug into the low beam plug on the passenger side?

[xs-style]

Somebody? Anyone? I just need to know if the lmc harness plugs into the passenger side low beam harness or the driver.

[xs-style]

Ok so since nobody chimed in, I just plugged it up the way I thought it should go. I went with the passenger light like I did on the 78.

Not exactly a success yet.... When I tried the switch, all four lights came on while on low beam. On high beam, only my passenger side low beam is on. I guess I'll try swapping some things around and see if anything works. If anyone that actually knows what they're doing has any pointers, that would be greatly appreciated.

[1957 Chief]

Free bump for you brother.

Bubba

[Mattchu60]

I am no help, but I also bought a relay kit from Classic Parts and it has no instructions, so I'd be interested to see what someone says that has done this!

[xs-style]

See here's my problem. I'm a don't let the smoke out of the wires kind of electrical guy. If I can buy a premade harness, great. I'd rather do that than risk burning the truck down attempting to do it on my own. These things come with no instructions but they're pretty straightforward. With the differences in the headlights you can't plug em in wrong as far as the lights themselves go. I had to drill some spots for grounds, but most people can handle that. That's why I was asking here about plugging in on the left or right sides. No one answered, but I'm here to say that neither way worked.

Plugged into the driver side, nothing happened. Plugged into the passenger, I had all four lights on with the low beams on, and nothing on when I switched to high beam. I tried swapping the relays around thinking that maybe it was a bad relay. When I swap them, I ended up with all four lights on on the low beams and then the low beam passenger light on when I turn on the high beams. I even went as far as to pull the two relays from the same setup that I have in my 78. That left me with the same all four lights on on low, nothing on on high.

Which leaves me with where i am now. I've just fished pulling the harness back out, and plan to send it back. As I told my wife, I'd rather drive my truck with crappy stock lights than not be able to drive at night at all.

So don't feel bad, I guess I'm no help either lol

[Sabaka454]

This is a simple circuit. Are you trying to simply bring relay current directly from B+ to the headlight to avoid unwanted voltage drop? Are you trying to have all 4 on all the time? What is your goal?

[xs-style]

Well these harnesses are supposed to work by bringing current direct from the battery, lowering voltage drop and making the lights brighter. Only this one didn't do such a great job of it.

[xs-style]

Update: i received the second harness from the seller and hooked it up tonight. Still have the same problem with all four lights staying on while on low beam.

I guess anyone wants to learn from my experience... The headlight relay mod is nice. I've got it on my 78 and it does help. But apparently if you have a four headlight setup, these premade harnesses just aren't gonna work.

[gmachinz]

Well whoever made that kit didnt build it correctly. LMC doesnt vehicle test their stuff and they have zero technical support because of this so they just go by customer returns as to how well something works is my guess. The low beam tans are wired in series while the green high beams can be in parallel/all-in-one with regards to wiring-how that kit has managed to goof it up I couldnt tell ya-but it may have something to do with having no R&D department in Shenghanzoi-ding-dong Province I'd imagine.