Some past threads have discussed the need and benefits of adding relays for the headlights in our trucks - better illumination and removing the electrical load from the headlight switch.

Some members have made-up their own harnesses while others [me] have purchased the one from LMC, which is plug-and-play. It also has been discussed that it almost impossible to find replacement relays, due to the fact that the 30A ones supplied with the LMC harness are 4 pin rather than the more common 5 pin found at most auto parts stores.

Yesterday, I received a new LMC catalog and was pleased to see a new addition... yes, the replacement relays listed right below the heavy duty harness. The part number is 47-3652 and the price is $4.95 each.

By the way, I have installed two of these systems. One in my son's 1984 F150 and the other in my 1986 F150. We have had no problems and are quite pleased with the increased brightness, due to getting full voltage to the headlights. However, you need to install a fuse in the line which feeds power to the relay. There are two such lines with each kit; one for high beams and the other for low beams. For some reason, this was omitted as delivered. A 10 or 15 amp fuse should be sufficient for any legal wattage bulbs used.

 

Thanks for the update. I'm going to do that upgrade at some point and am undecided as to whether to build or buy. But this info helps.

 

Gary,

Based on reading threads where you are concerned [enjoy them!], I feel confident you could "build a better moustrap", but the quality was quite good, installation was very easy, it looks good and it cost $29.95. With all you have going on, this could be done in a snap and you could concentrate on the more difficult aspects of your project(s).

Just my opinion, David

 

David - Thank you for that, I will take it as a compliment. I'm leaning toward buying as well. With the relays costing $5 each we are now at 1/3 of the cost. And, I would have to create an "8 page micro-analysis" to figure out which relays to use, where to put them, and whether to use fuses or breakers.

But, on the fuse/breaker subject I would lean strongly to a breaker. I believe our trucks have them, and the advantage is that your lights come back on when the breaker cools down - assuming you use the auto-reset style. In fact, having a parts truck, I may know exactly where to get some!

 

I've been eyeing this type of harness for a while. The "oddball" relays used in it was something that bothered me a bit. Now that they list replacements for these, I might just have to order a few kits. Same kit fits everything I own, aside from the 95 B2300......

Want really bright high beams? Run a jumper wire from the relay for the high beams to the trigger wire for the low beams, so both are used for the high beams.

 

I tried a 30 amp mini breaker like what would go in your fuse panel, but it kept tripping every couple seconds. I ended up putting an 80 amp plastic-cased fusible link right at the starter solenoid and it took care of the problem. 80 amps is a bit much I thought, but it does give me some headroom if I want some higher wattage bulbs later.

And I have thought about doing that, Rogue, but I was worried it'd burn out my bulbs too soon. Or will it not?

 

I'm certainly no electrical genius but I did the headlight mod 2 weeks ago. I started from scratch.

I went to the junkyard and pulled the "bosch" style relays from some GM cars. They are the 5-prong type. I bought some wire from Home Depot and found fuse connecters at the junkyard as well. I soldered everything up and connected the wiring to the relays I pulled from cars and my headlights work fine.

Correct me if I'm wrong but the only difference between the 5-prong and 4-prong relay is the 5 prong also has an 87a prong. Which is simply just another 87 and you could use that in place of the 87 or leave it alone as it makes no difference if it's hooked up or not.

 

Good point.

You could probably modify the LMC harness to accept the five prong relays by replacing the plastic relay connector with spade terminals.

 

Could you post some pictures of how you laid it out, where you put the relays, etc?

Or cut the 87a connector off a 5-pronged relay, assuming the rest line up as I'm not familiar with the 4-pronged one.

 

I think the LMC relays are rectangular in shape where the connector fits, where the 5 pronged ones are square. Overall they have a different appearance.

Another idea would be to go to the JY and grab some factory relays with OEM plugs and just replace the LMC connector with that. Then you would have a more common connector type. You could then get replacements by going to the parts store and asking for a such-and-such relay for whatever vehicle you got it from. I think Ford had setups like that, maybe even on F-Series trucks, but I'm not certain.

But for all that work and time, you could just buy a set of proper replacement relays from LMC for $5 each.

 

I'll try and do it if I remember this weekend. It's not perfectly pretty since I only bought 2 colors of wire but it definitely made things brighter and is cheaper than going with the full kit.

I just followed the instructions in the thread about how to make your own. I didn't even know these existed until one of my headlights died a month ago and I did a headlight search and found the upgrade.

 

There you go, being logical and reasonable again. What's the fun in that? You sound like Chris: No need for a drain plug, just suck it out with a hose suction gun. With friends like that I might get something done!

 

 

No.
I went through this last week in another thread.
The 87A terminal is normally closed, i.e. hot when the relay is not triggered.
There ARE relays with two #87 terminals, but the pin is not directly between the 85 & 86 terminals as the 87A terminal is.
The LMC relay is a cute little thing with a self locking plug, but does NOT have the same configuration as a normal 'Bosch' style relay.

$30, plug'nplay, it's a no brainer for me.
Don't forget to fill the lefthand headlamp plug that you abandon with dielectric silicone to keep it from filling with debris or water.
I hooked mine up with a fusible link, but I can't imagine it failing before the bulb filament burnt out.

 

I didn't know that about 87a being hot when 87 isn't. Hmm, ideas...

I had one factory headlamp plug short to ground after I installed the relay kit and it caused me all sorts of crazy problems until I found that the terminals had backed out of the plastic connector just enough where they could touch a ground. I routed it out of the way where it's away from metal and it's been fine, but a little tape over the whole thing might not be a bad idea.