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I know there was a post for this cant find it though. Just need to figure what goes where sure i could figure it out but when you have a LUV encyclopedia here why pound my head against the wall.

Thanks
Ox

Hi Ox.

What year truck are you putting the dual headlight set up into?

I'm moving the electrical system from an '82 into a '75 and therefore I'm going from a single headlight system to a dual headlight system as well. The way the dual headlights are wired up is that the ground and the hi-beam wires from the dual element, outside bulb are also connected in parallel to the single element, inside bulb.

On the '75 there is a separate fuse for each low beam light and separate fuses for each pair of high beam lights. Each of which is a 10 amp fuse. I'm guessing you are switching the dual head light set up into a '76 to '80 truck. I don't know what your fuse situation is like, but in '82 the headlights aren't on fuses but rather have a circuit breaker.

The '75 dual element headlight is listed as 37.5/50w and the single element headlight is 37.5w.
The '82 dual element headlight is listed as 55/65.

On the '82 I understand this to mean: 55w low beam and 65w high beam per side.
On the '75 I understand this to mean 50w low beam and 75w (2 * 37.5w) high beam per side.

If I'm correct on the above, the circuit breaker will have no problem with low beam as it's actually 5w less per side. High beam, however, ends up being 10w more per side.

The two 65w high beams on the '82 pull 130w. This is 10.83 amps.

With four 37.5w bulbs it will pull 150w. This is 12.5 amps and the 1.25mm wire used in the headlight circuit is rated for 18.8 amps so that shouldn't be a concern. The only thing I'm not sure of is what the circuit breaker is rated for. I pulled it out and it didn't have any ratings on it but there is a part number and below that the number 24. I'm not sure what the 24 means. It seems too high to protect an 18.8 amp rated wire.

So in summary, I'm not sure if the circuit breaker will handle 12.5 amps but I'm hoping the circuit breaker is oversized enough to handle the extra ~1.7 amps.

That's quite a bit of rambling but hopefully some of it helps you.

Eric Q.

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'75 body with '82 diesel running gear
My build thread.

Have 78 truck. That was a little confusing to me but i understand where your going... I know there was a whole thread on this subject and that it had "pretty" pictures!!!!

lol.

Assuming you have the wiring harness from the dual headlight truck, cut the wires off, put spade connectors on each, and stick them in the connector that used to connect to the single headlight like below and hope the fuses/circuit breaker is big enough.


Eric Q.

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'75 body with '82 diesel running gear
My build thread.

Now that I can work with thats what I was going to try if not just by bigger fuses!! Figured out of the three wires on the single light one of those had to be the High beam Ill see what works

Thanks First post makes sense as well now!!!

OX

I did this on my 79 a while back. There is a thermal circuit breaker up under the dash for the headlights on the 78-later models, but I did not have any problems with it tripping with the 4 light setup running off it. If it does trip it will reset once it cools. That was with basic stock wattage bulbs though.

I was always going to wire in relays to the stock wires and then run the relays right off the battery to the lights, but I never got around to finishing it. Somewhere around here is a post on how to wire the bypass relay. You end up with brighter lights (less wires/switches from bat to bulb) and you can fuse them to better match the bulbs you are using.

_________________
95 Isuzu Trooper Daily Driver
86 Isuzu Trooper reliable backup
77 LUV 2wd stock beltway blaster (resting)
79 4x4 LUV project: 2.6L, 5spd, 31s (eventually)

MEPR: Man, my 4x4 makes all other LUVs look good