Need Light Placement Input

ScottyBoy

No, that's not a banana in my pants.
Joined
Jun 5, 2009
Posts
13,668
Reaction score
3
Location
Shreveport
Also, in case you haven't found it yet the parking lights will be a dark brown wire on that truck. :thumbs:
 
B

Bernie

Guest
On another side note:
Do I need to make a harness like this? - Look at the diagram below the image.
I don't really understand the point of this though. Some guys have said that the newer GMT400's need a relay harness whereas the older ones don't. I'm not sure what happens so you know you need one, but I'm sure I'll find out when I try to use them without a relay harness.

Is the question "Do I need this for my HIDs" or is it "Do I need it for the LEDs?"

For HIDs, yes, for LEDs, no.

GM trucks, up until '01 or '02 (maybe even beyond) used undersized wire for the headlamp feeds, which means the bulbs get less voltage than they actually should. To correct this a few places sell (or you can make it yourself) a wiring harness that uses a relay to control the headlamps, and feeds them directly from the battery with proper sized wiring. It plugs right into the existing harness and uses the power that would normally be illuminating the headlamps to just energize the relays (one for each bulb), which then feeds them power direct from the battery. HIDs can be very sensitive to voltages, and if the voltage is too low may not even illuminate.
OK so I guess I'll need to use a relay then.
Can I buy a factory end that is on the wiring harness of the vehicle (male end; 2 prong) at my local parts store so I can still make my harness plug-and-play?

Most good parts places will have those, or be able to order them.
 

nubuilder

Why buy new when you can restore?
Joined
Mar 10, 2010
Posts
10,154
Reaction score
4
Location
La Crosse, WI
Also, in case you haven't found it yet the parking lights will be a dark brown wire on that truck. :thumbs:
Thanks Scotty. I'll look for that on the back side of the headlight knob. (haven't started yet; hopefully Sat if not Sun)

Most good parts places will have those, or be able to order them.
I'll start checking AutoZone, Advance Auto, and O'Reilly web sites tonight. If I can't find them there, we have a CarQuest, NAPA, and another large, local shop that has more stuff than I can imagine (United Auto Supply if anyone cares).

EDIT:

Found some, but they are only the connector; not pigtail. But I'm guessing it is pretty easy to put the wires in the connectors and crimp them in. $2.79ea at Advance Auto (AutoZone & O'Reilly $5 or more).

So I'm guessing that now I'm gonna need 3 relays to make the lights work.
1 - relay from stock low beam wiring to relay that gets power from battery/fuse box
2 - relay from stock high beam wiring to relay that gets power from battery/fuse box
3 - relay getting signal from high and sending power to low; getting power from battery/fuse box

OR can I eliminate a relay and send the signal from the stock low beam wiring AND the new high beam wiring power ALL (both signals) to the relay for the new setup for the low beams

Does this make any sense at all?
If not, please re-write to clarify.

Will 14ga wire be enough for all this wiring? A chart I found (HERE) says that 14ga can handle 40amps. And using their equation, Amps X Volts = Watts, it can support 480watts??? Seems high.
 
Last edited:
B

Bernie

Guest
Also, in case you haven't found it yet the parking lights will be a dark brown wire on that truck. :thumbs:
Thanks Scotty. I'll look for that on the back side of the headlight knob. (haven't started yet; hopefully Sat if not Sun)

Most good parts places will have those, or be able to order them.
I'll start checking AutoZone, Advance Auto, and O'Reilly web sites tonight. If I can't find them there, we have a CarQuest, NAPA, and another large, local shop that has more stuff than I can imagine (United Auto Supply if anyone cares).

EDIT:

Found some, but they are only the connector; not pigtail. But I'm guessing it is pretty easy to put the wires in the connectors and crimp them in. $2.79ea at Advance Auto (AutoZone & O'Reilly $5 or more).

So I'm guessing that now I'm gonna need 3 relays to make the lights work.
1 - relay from stock low beam wiring to relay that gets power from battery/fuse box
2 - relay from stock high beam wiring to relay that gets power from battery/fuse box
3 - relay getting signal from high and sending power to low; getting power from battery/fuse box

OR can I eliminate a relay and send the signal from the stock low beam wiring AND the new high beam wiring power ALL (both signals) to the relay for the new setup for the low beams

Does this make any sense at all?
If not, please re-write to clarify.

Will 14ga wire be enough for all this wiring? A chart I found (HERE) says that 14ga can handle 40amps. And using their equation, Amps X Volts = Watts, it can support 480watts??? Seems high.

Your relays are probably rated at 30 amps, so 14 ga. will be fine. I wouldn't try to eliminate one of the relays in the headlamp setup unless I knew exactly what the current draw was going to be. Too easy to exceed the capacity of the relay, or push it to the limits. Also, check your HID package and see what it comes with. They may have included a harness as part of the installation kit. In fact, I'd be surprised if they didn't.
 

nubuilder

Why buy new when you can restore?
Joined
Mar 10, 2010
Posts
10,154
Reaction score
4
Location
La Crosse, WI
Your relays are probably rated at 30 amps, so 14 ga. will be fine. I wouldn't try to eliminate one of the relays in the headlamp setup unless I knew exactly what the current draw was going to be. Too easy to exceed the capacity of the relay, or push it to the limits. Also, check your HID package and see what it comes with. They may have included a harness as part of the installation kit. In fact, I'd be surprised if they didn't.
My relays are 40a (support 4x 55w driving lights or 2x 150w off-road lights), but I will be using a 20a fuse or whatever the HIDs draw (I won't go bigger than 30a, but nothing needs anything that big anyways).
When I get the HIDs, I'll see what their rated amps are and let you know.
I don't think they will come with a relay harness since it is sold separately on DDM Tuning's website.

I don't think my idea of eliminating a relay would draw any more power than they already are. The highs will have their own relay (since factory wiring won't be enough) and so will the lows (for the same reason). I was just trying to say that the low beam relay could get its "signal" from 2 different sources : the factory low beam wiring and the old high beam wiring. So both relays would still be drawing and having the same amount of electricity pass through them.

But like I said, I'll see what the packaging says when they come tomorrow.
 
Last edited:

nubuilder

Why buy new when you can restore?
Joined
Mar 10, 2010
Posts
10,154
Reaction score
4
Location
La Crosse, WI
Hey Bernie, here are what the ballasts say:

35w
V in = 9-16 V DC
V norm = 13.2 V DC
I norm = 3.2 A
I in max = 5.5 A
Pout = 35 W norm
T case = -40 deg C ~ 105 deg C
V start 23 KV max

55w
They don't have stickers on them !!!!!!!
 
B

Bernie

Guest
Hey Bernie, here are what the ballasts say:

35w
V in = 9-16 V DC
V norm = 13.2 V DC
I norm = 3.2 A
I in max = 5.5 A
Pout = 35 W norm
T case = -40 deg C ~ 105 deg C
V start 23 KV max

55w
They don't have stickers on them !!!!!!!

So, the 35's draw between 3.2 and 5.5 amps each, which means the 55's probably draw between 5.0 and 7.5 each. With a relay rated at 40 amps you should be fine. Use a 15 amp fuse and see if it blows. If it does, bump up to a 20 and you should be good.
 

nubuilder

Why buy new when you can restore?
Joined
Mar 10, 2010
Posts
10,154
Reaction score
4
Location
La Crosse, WI
Well, I'll start with 15 amp and keep stepping up to 30 amp if I have too.

Does anyone have the 55w ballasts that could give me the same info I posted for the 35w?

I'll be starting on the wiring this afternoon I hope. We'll see how it goes.
 

Members online

No members online now.

Forum statistics

Threads
28,735
Posts
1,103,127
Members
4,710
Latest member
ready67
Back
Top