Questions about swapping old sealed beams for hella e-codes….

So after owning this 1996 taco since it was new I am finally upgrading the headlights. Better late than never!

Electrical stuff isn’t my forte and almost nothing about is is very straight forward for me. Also, I don’t have a multimeter or even know how to use one.

I have the e-codes in hand and was intending to do the swap while initially keeping the stock wiring and stock wattage bulbs before deciding whether to upgrade the harness. While I was doing some reading in order to have a clearer picture of how to go about the swap, I came across a post somewhere here - I can’t seem to find it now - indicating the old sealed beams and the wiring in the truck were slightly different than the new H4 bulbs. The post had a diagram which showed two of the three wires going into the connector need to swap positions for the new bulbs to work properly. It was some combination of either the low or hi beams and the ground were in opposite positions and need to be reversed. I have done quite a bit of reading on headlight upgrades and don’t recall ever seeing this wiring issue except for once a few days ago on a post I can’t seem to locate.

Anyway, can anyone confirm if the new H4 bulbs are plug and play with my existing connector wiring or if I actually need to swap positions on two of the three wires where they go into the connector? I think this is only applicable to 95.5, 96 & 97 models as I’m pretty sure the headlights on 1st gens were changed in 98. I really would like to be able to complete this task in a single day and since I have no electrical troubleshooting skills or tools I’m hoping someone might know for sure or make suggestions of possible multimeter work arounds to determine which wire is which etc.

One idea I had was to just plug in the hellas before beginning the project and see if hi/low beams work properly, but I’m not sure if this could help me figure out if it is wired correctly or help me determine which wires need swapped. Also, is there any risk of damaging the wiring or other electrical components if I attempted this? Is disconnecting the negative cable enough to do this work safely or should I completely disconnect the battery?

 

Alrighty, this is a fun one! I went through this many years ago when I converted to e code H4 housings with Hella 110w bulbs. Even though the sealed beam and the H4 bulbs use the same connector they do not have the same wiring. You need to swap two of the wires:




Verify with a multimeter but this should put you on the correct path. Instead of cutting the factory harness I added a H4 relay harness at the same time to support the larger draw of the bulbs and it was pretty painless to repin the connectors and get things working.

Here's the harness I used:

$50 Octane Lighting H4 100w Ceramic Fused PnP Heavy Duty Automotive Wiring Harness Headlight Foglight Booster Relay 12v

https://www.amazon.com/Octane-Lighting-Automotive-Headlight-Foglight/dp/B00BMN30HY

 

Well, first, get yourself a multi-meter. They cost like $15 for a decent one. A digital auto-range one. That will automatically adjust the sensitivity.

It's not as scary as you might think to do some testing on car wiring.

To find out which wire is the +, turn your headlights on, then touch the neg lead of your new multi-meter to something metal on the chassis, then touch the other lead to one of the plug leads. if it reads a voltage (12 ish volts), that's your + wire. The other is the ground (neg) wire. Do that for the high and low beams.


If you end up doing the upgraded wiring harness as described in the proper headlight upgrade thread, there's a test that's spelled out on how to make sure you get the right harness. Once you get the right harness, it's plug and play.

 

Thanks @Wulf! That is the diagram I was attempting to locate.

@jbrandt, Thanks for your input. I am a little apprehensive about the electrical stuff.

Do you think it’s a safe bet to just use the above diagram without using a multimeter to check? I’ve been leaning towards getting a harness in order to get as much voltage as possible going to the bulbs even though I intend to stick with stock wattage bulbs, at least initially. I am expecting a drastic improvement as the sealed beams are so bad I mostly avoid driving at night unless I am familiar with the area.

I will probably get a multimeter at some point. Do I really need to preform the test to determine which harness? Since I don’t have DRL or fog lamps and being a 96, isn’t it definitely ground switched? Is just ordering a ground switched harness a bad idea?

I was hoping to get the housings swapped while using my current wiring in the next couple of days, but if you guys think I should preform the tests rather than wing it I will follow your recommendations.

 

Go grab a HF multimeter and probe it.

 

@Wulf is a good guy and knows what he's talking about. But no, I don't think it's a good idea.

Not because I don't trust him, (although when you break it down, he is just some dude on the interwebs... ) but because it's a great opportunity to learn something. Get your voltmeter, and see if you can replicate what he's saying. put the + lead of your voltmeter on the high beam tab and see if you get voltage.

BOOM.

Knowledge.

 

Thanks for the input. I'll pick up a multimeter and give it a go.

 

What's the worst that could happen?

 

Haha....That's what I'm afraid of!!!

 

I like to think I know what I'm talking about but it's also been 8 years since I did the swap so verifying is definitely important here

 

I kid, I kid...

Just don't cross 2 wires with one of the leads on the voltmeter. You (probably) won't die, but you might blow a fuse.

And any time you start messing with moving wires/plugs around, disconnect the battery.

Just sit and watch a series of videos of people trouble shooting car wiring, and stuff like that. There are plenty of videos that show the basics of how to use a voltmeter, too.

It always helps to make a conceptual drawing of what you're trying to do, too.

Best of luck!

 

I finally got a multimeter and checked the voltage on both the low and high beams. I'm not 100% clear on what the numbers mean. I assume the one nearest 12v is the + and I think the .4 readings may be ground, but I’m definitely not too sure. Here is a drawing showing what values I found at the socket.