Wiring a light bar to headache rack

[m denali]

I have a 2020 gmc denali 2500 duramax and I'm trying to wire my flood light bar to my magnum rack so it works when I back up when the cargo lights are on. I had it wired on my 2018 denali 2500 to work like this but when I wire it to the lights in the bed on the 2020 it cuts out as if it's drawing to much power. Any ideas to as why or any info on a way to wire it so it stays on. Thanks 

[mkeddie]

Use a relay to connect it..depending on bar size u probably are over drawing it

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[m denali]

Where would I get and install the relay

[Tomato]

1 hour ago, m denali said:

Where would I get and install the relay

Any chance you could post a pic of your truck with the rack?  I am thinking about adding one.  Thanks.

[mkeddie]

The wire attached to 86 will be the wire from the bed light
30 main power fused as needed
87 to light bar power
85 to ground


When ur bed light turns on it will turn the relay on and turn bar on

YouTube relay wiring for better understanding

Any auto store has relays

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