headlight modification

[meatwagon83]

i put silverstar sealed beams and relays in my headlight harness today, and my headlights are SUPER FRIGGIN BRIGHT!!!!!! thanks for the ideas guys!!

that is all.........andy

[texas gmc]

I'd like to do mine.
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[bilfman]

I did the same with mine using hella's from amazon. 34 bucks a pop , bulb included. Sourced relays locally for $7. Wow what a difference over the old sealed beams. I will probably put silver star bulbs in, later down the line. If you do plan on this getting an old harness from a wrecker lets you maintain your stock one. Do your relay hacking on the wrecker harness and just tap into your truck one with some spade connectors. That way you can be back to stock in seconds.
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[izzy_Britton]

I am interested in this mod, i think? is this similar to what LMC offers as their headlight wire harness for direct connection to the battery or some such thing? please share the info on this mod. thanks.

-Izzy

[meatwagon83]

its the same mod i just got some relays off the firewall of a 91 suburban and made my own harness, i got a diagram off the 73-87 truck site, im sure there is one on this site too, to many guys here have done it!

[izzy_Britton]

Originally Posted by meatwagon83

its the same mod i just got some relays off the firewall of a 91 suburban and made my own harness, i got a diagram off the 73-87 truck site, im sure there is one on this site too, to many guys here have done it!

Any body have a link to the mod details? I have been looking at this picture for the last couple hours and i am totally baffled as to where the connections are actually made other than the obvious headlamps and battery.



Any further info would be greatly appreciated.

I have a 86 that i will be converting the front over to 89-91 and would love to do this mod while i have it apart.

-Izzy

[83GMCK2500]

Izzy...where are you lost? The OEM setup routes all of the current that is delivered to the lamps through the dimmer switch and the headlamp switch. That circuit remains unmodified, it is used as the "low current" or control circuit for the relays. The high current side of the relays connect to the junction block on the firewall, or other more direct path to the battery and to the lamps.

I think the connections that you are looking for are the 11/150 and 11/12/150, where they used to route power directly to the headlights they are now used to control the relays.

We do have a vendor that sells a rather impressive harness using high quality components: HERE

[meatwagon83]

yup, thats the diagram i used! i was going to buy that harness but i didnt have the benny to blow on it!

[wraprail]

As I posted in the other thread, pole 85 on the relays and circuit 150 at the headlights are chassis -ground. The do not need to be connected together as is shown on the diagram.
Only one fuse (30a) is needed. Split the wire or jumper between pole 30 on the relays.
You can install your relays on the firewall where the harness connector is.
Cut the harness right there and splice in your relays. There is plenty of slack in the wires.
The relays are marked on the underside
To make it easy, find the high beam hot wire (use a test light) cut it, the switch side goes to 86 and the highbeam side goes to 87.
Lowbeam hot wire do the same thing on the other relay. 86 and 87
hook both pole 85 together and ground.
Hook both 30 together, then to fuse and power. Use at least #12 wire.
All the other wires are factory and should already be there. Nothing more is needed.
Thats it.

[izzy_Britton]

I am revisiting this thread and while i am working under the hood on a few things.

after reviewing the info above i think i understand most of the wire routing now that i have a relay in my hand.

My new question is about the relays themselves.

first what relay is recommended for this mod?

the relay i have in my hand at the moment is a BOSCH 0 332 204 150 The only difference between this relay and the pin-out imaged is that there is an extra pin, 87a

thoughts?

-Izzy

[meatwagon83]

i dont remember what mine are, like i said i got them off a 91 subs firewall buy the distributor

[lilpoindexter]

Has anyone tried the LMC headlight harness for single headlights? i'd like to try this on my '78, but some of the LMC parts i've recieved have been hit or miss. The dim yellow lights just ain't doing nothing for me at night.

[izzy_Britton]

Originally Posted by meatwagon83

i dont remember what mine are, like i said i got them off a 91 subs firewall buy the distributor

Are you talking about the great big relays that are bolted to the firewall to the passengers side of the distributor? arent those for the fuel pump and something else? i didnt think they would work, they seemed like they were way wrong when i looked several weeks ago. maybe i seen something different?

-Izzy

[izzy_Britton]

Originally Posted by lilpoindexter

Has anyone tried the LMC headlight harness for single headlights? i'd like to try this on my '78, but some of the LMC parts i've recieved have been hit or miss. The dim yellow lights just ain't doing nothing for me at night.

Basically that is exactly what this mod will do for pennies on the dollar compared to the LMC version. just DIY.

-Izzy

[meatwagon83]

Originally Posted by izzy_Britton

Are you talking about the great big relays that are bolted to the firewall to the passengers side of the distributor? arent those for the fuel pump and something else? i didnt think they would work, they seemed like they were way wrong when i looked several weeks ago. maybe i seen something different?

-Izzy

those are the ones i used, they work great! i have a buddy that used the same ones on his 79 and they work great as well

[izzy_Britton]

OK THEN! monday i will aquire these and start my harness mod. maybe i was looking at something different or maybe it just didnt click in my head when i was looking at them. I know that these are the fuel pump relays and such and are about 90$ (or used to be about 90$) at the stealer, so maybe that is why i shied away from them... who knows.

but now i can start the mod.

-Izzy

[anubisani]

I WAS thinking of buying this setup
http://www.ebay.com/itm/330788750080...84.m1436.l2648

[wraprail]

Originally Posted by izzy_Britton

I am revisiting this thread and while i am working under the hood on a few things.

after reviewing the info above i think i understand most of the wire routing now that i have a relay in my hand.

My new question is about the relays themselves.

first what relay is recommended for this mod?

the relay i have in my hand at the moment is a BOSCH 0 332 204 150 The only difference between this relay and the pin-out imaged is that there is an extra pin, 87a

thoughts?

-Izzy

87a is normally closed (where 87 is normally open) so you would just leave 87a open..( not connected)
The Bosch relay you have is ideally suited for this applacation. Its the same relay the aftermarket harness uses as well as most car alarms use.

[izzy_Britton]

Originally Posted by wraprail

87a is normally closed (where 87 is normally open) so you would just leave 87a open..( not connected)
The Bosch relay you have is ideally suited for this applacation. Its the same relay the aftermarket harness uses as well as most car alarms use.

Thank you for the insight wraprail. I found these in a square, 4 of them and a little 10 wire module all wired together, screwed to the back of the steering column/dash plate. I thought at first it was an alarm or something but they are all wired together, in series (i guess that is what i would call it). I wondered if it was a DIY heardlight or window motor thing.

so yeah i have 3 relays and 3 wire connections. ready to rock and roll then.

thanks again wraprail.


-Izzy

[bojak]

Originally Posted by lilpoindexter

Has anyone tried the LMC headlight harness for single headlights? i'd like to try this on my '78, but some of the LMC parts i've recieved have been hit or miss. The dim yellow lights just ain't doing nothing for me at night.

Yes I just did the single headlight harness from LMC with new headlights and it is great. Really simple to do and the results(especially how terrible it was b4) are awesome. This was money well spent IMO.
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[Redcap]

Originally Posted by anubisani

I WAS thinking of buying this setup
http://www.ebay.com/itm/330788750080...84.m1436.l2648

I like this idea.

[meatwagon83]

however you do it this is a worthwhile modification, after i did this my brights light up signs more than half a mile away! no joke!

[wraprail]

Originally Posted by meatwagon83

however you do it this is a worthwhile modification, after i did this my brights light up signs more than half a mile away! no joke!

I agree 100%. This gives and a very noticable improvment for very little cost no matter how you do it.
Just don't follow clint's advice. lol

[izzy_Britton]

Who is Clint and what was the advice he gave that i should not follow?

also the ebay wire harness looks like a good price, hard to say how well it is constructed, but looks good. my only question about the above mentioned ebay item is...

WHERE the heck does this plug into?


I do not recall seeing anything where that would plug in under my hood. maybe this is just a generic photo and the harness for our trucks is slightly different?

-Izzy

::Edited to reduce photo size::

[izzy_Britton]

Originally Posted by meatwagon83

those are the ones i used, they work great! i have a buddy that used the same ones on his 79 and they work great as well

Your talking about THESE right?



These are from a 89 and 91 suburban. they are a 5 pin relay with each pin labeled A - F (there is no pin B however).

I now have these and a set of the 5 pin bosh relays, I like the GM relays because they are weather proof and look factory if i can use them. do you know the PINOUT for these? are these the correct ones that you mentioned?

-IZZY