4 headlight mod

[FirehawkNS]

Has anyone tried to do a 4 headlight mod to a 2000 model Silverado? I did it too my Z and want to do it to the Truck. For those that don't know, when you turn on your highbeams, the low beams cut off. With the 4 headlight mod, the low beams stay on with the highbeams!! Just curious if anyone knew off the top of the head which wires to jumper on the truck too make this work.

[silveradoman]

There was some info on this on another thread, someone said the bcm cuts the negative wire to the low beam only, but I haven´t verified it, for fear of frying the bcm

[walbern1]

1) Open hood

2) Remove brace from firewall to Driver's side fender.

3) remove top of Circuit panel

4) unhook the snaps from the passenger and drivers side of the cover...look hard they are there!

5) Roll entire circuit board over towards the passenger side.

6) Locate the Grey connector...there is only one.

7) at location D3 (3rd down 4th to the right) is a light gauge yellow wire. It is the only yellow wire in this row.

8) Tap this wire and ground it to the Light ground on the firewall. Follow the lead from the Hood mounted light, and you will find it ...just to the left (YOUR OTHER LEFT!!!) of the Master Cylinder.

9) Put your stuff back together...you are done...arent you glad you kept that cover?

Enjoy your new quad headlights!

I cut and pasted this from another forum but have done this and it works great. There is another way to do it using a relay but this is alot easier and since your working on the power side and not the dround you don't need a fuse. The lights themselves are fused on the power side of the circuit

[gtmud]

This doesn't overload the power wire, running both lights? What about the heat factor of having both lights on int he housing?

[vnotaro]

Originally Posted by gtmud

This doesn't overload the power wire, running both lights? What about the heat factor of having both lights on int he housing?

I often thought about having all four lights on at the same time but always wondered about the heat it would generate too.

[chuck16]

Walbern. Any pics to go along with this????

[silveradoman]

Does the kit they sell at styling concepts do this same thing?

[walbern1]

I didn't take any pics of mine when I did it and haven't found any pics of this mod in any of the forums. I have done it this way and with the relay to switch the ground and haven't notice any increased heat due to it. Because all you are doing is grounding a circuit to which power is already supplied you shouldn't have any additional heat (you aren't supplying power to both lights through the same circuit only grounding both at once)

[quaddriver]

your best bet is to use 2 relays and isolate the low beams during high beam operation

I do this on my 88 (which is altogether different wiring)

when the lights are negatively switched, you have a fused (not breakered) relay connected to the highbeam ground, this relay then fires 2 additional relays, one isolates the low beams from the constant power and attaches to a different breakered power source, the other relay isolates the factory ground and supplies one.

If the highbeams are positively switched, you dont need the first relay, the high beam power can be tapped to fire the 2 isolation relays.

you CAN do this with big to3 cased power transistors, but the voltage drop across the pn junctions will lower the voltage to the headlights.

the beauty of this isolated system is, if any relay fails, the truck reverts to factory operation.

why do this? the main supply circuitry can really only handle the current of 1 set of headlights without risking failure.

[gschretter]

You hit the nail on the head.

I added two hella 140watt lights to the front of my truck.

I used a relay and the trigger is the high beams.

So when I hit the high beams boom day light.

[Powerwagontim]

8) Tap this wire and ground it to the Light ground on the firewall. Follow the lead from the Hood mounted light, and you will find it ...just to the left (YOUR OTHER LEFT!!!) of the Master Cylinder.I need clarification on this point. By "tap the wire" do you mean disconnect it from the board, or splice another wire into it? or something altogether different?
Thanks, Tim

[walbern1]

Splice another wire into it.

[Lucky519]

Is there a way to dot his on my 1994 Z 71? Is the wiring more similar to the 2000 or the 89?

[silveradoman]

cAN YOU PUBLISH THE DIAGRAM?

[walbern1]

Here try this. This guy took pictures of the entire process.
http://chevytruckworld.tenmagazines....70-album-12221
Or this is the other way;
Wiring the Relay 99-02 trucks
Wire up the relay as follows:

- 85 Purple wire

- 86 Either orange wire

- 30 Any metal bolt (negative battery terminal) True vehicle ground, negative battery terminal

- 87 Yellow wire

You only need to perform this mod on one side for it to work with both of your headlights. It doesn’t matter which side.

Turn headlights on. Your low beams should now stay on with your high beams!



Under a stock configuration the head lights will work as follows:
Low beam:
Yellow wire – at resting state “off” is 12V+, drops to ground when turned “on”
Orange wire – remains at 12V+ constantly

High beam:
Purple wire – at rest “off” is 12V+, drops to ground when turned “on”
Orange wire - remains at 12V+ constantly