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Correct All 4 on Hi harness?

Big T

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Trouble shooting the headlights on my ‘99 K2500. While testing at one of the relays in the All 4 on Hi harness, the cover on the relay simply broke apart. Testing revealed other issues and there was plenty of corrosion. So it’s time to replace the All 4 on Hi harness and I can’t remember the correct one. Is this the correct harness (note: the check fit function does not work):


IMG_3276.png
 
Painless Wiring web site is anything but painless. Vehicle selection stops at 1991...weird.

The harness pictured is NOT the Four High harness. Call to be sure but it looks like the 30821 is the one you need for Four on High.
https://www.painlessperformance.com/wc/30821

From the site: "Note: Kit is compatible with all 1999-2002 GM trucks with low beam daytime running lights. Some 1999 and later trucks wiring did not change. If your headlight wires are tan and green please use kit #30802; if you see purple and yellow please use kit #30821.

The 30817 harness pictured replaces the OEM headlight harness so power is pulled from the batteries and not run through the headlight switch. OEM switch just triggers the relay.
 
I have both of their harness; Heavy Duty 30817 and the Four-High 30802.
IMG_9240.jpeg

The 30821 Four-High kit has three wires and directs you to splice in to the Hi, Low and DRL circuits at the front of the Core Support but, uses a WeatherPack relay. The 30802 kit splices in to the harness in the engine bay as the relay isn’t weatherpacked. Seems you should be able to them both in the engine bay. I did with my 99 Burb.
 
Instead of the “T” or guillotine splices, I used 2 to 1 heat shrink butt connectors. Water mist in the engine bay getting in and corroding the T splices concerned me.

IMG_0161.jpeg

Something to consider given the seeing your corrosion on the relay.

That corrosion also confirms I need to change mine to a weatherpack set up too. I have a replacement on the shelf, just need to figure out how to make the conversion since the wire colors are definitely not the same as the kit. I had to do the same for the HID Reverse light harness I used to have on the truck since the relay was under the truck at the back and definitely not weatherproof.
 
Last edited:
I have both of their harness; Heavy Duty 30817 and the Four-High 30802.
View attachment 87793

The 30821 Four-High kit has three wires and directs you to splice in to the Hi, Low and DRL circuits at the front of the Core Support but, uses a WeatherPack relay. The 30802 kit splices in to the harness in the engine bay as the relay isn’t weatherpacked. Seems you should be able to them both in the engine bay. I did with my 99 Burb.
Painless customer support asked for my wire colors, which are tan and green. They then recommended 30821.
 
Painless Wiring web site is anything but painless. Vehicle selection stops at 1991...weird.

The harness pictured is NOT the Four High harness. Call to be sure but it looks like the 30821 is the one you need for Four on High.
https://www.painlessperformance.com/wc/30821

From the site: "Note: Kit is compatible with all 1999-2002 GM trucks with low beam daytime running lights. Some 1999 and later trucks wiring did not change. If your headlight wires are tan and green please use kit #30802; if you see purple and yellow please use kit #30821.

The 30817 harness pictured replaces the OEM headlight harness so power is pulled from the batteries and not run through the headlight switch. OEM switch just triggers the relay.
Check with Glagulator.

If I remember right, the harnesses I got were plug and play. No cutting or splicing
 
Check with Glagulator.

If I remember right, the harnesses I got were plug and play. No cutting or splicing
My existing I cut and spliced. I used heat shrink butt connectors. Though the connectors were not specifically designed for 2 into 1, I made them work.

I will see Paveltolz in person over the weekend on my way to Montana. I will be able to compare the two installs.
 
My existing I cut and spliced. I used heat shrink butt connectors. Though the connectors were not specifically designed for 2 into 1, I made them work.

I will see Paveltolz in person over the weekend on my way to Montana. I will be able to compare the two installs.
I like plug and play. Very easy to set back to original or to use the harness on another vehicle
 
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