Headlight problem

[andreww238]

i have an 02 7.3l.. headlights only work when key is completely off. as soon as i turn to accessory the lights go off.. any ideas? need help asap .. thanks

[bamaboy473]

What's changed with any electrical systems in the truck? Anything added or replaced?

[tony66]

New to diesels so this is a total guess. Left battery runs accessories. maybe when you turn the key on there is not enough juice to run them. Is it good or is it being charged properly?

[chillls]

possible relay problem
or the ground for the relay is not there

[enoyes12]

When the trucks running no lights either? Does the truck take a long time to start? I would agree to check the relay. Switch it with another one and see if it fixes it. It sounds as if u are getting a voltage drop or you are losing the ground when the accessory is energized. Try disconnecting one of the headlight plugs and see if one light will stay on. Can you pull the headlight switch and check it with a meter with key off and on to see if the problem is showing up there.