Lights

[Sapp]

I have a 2004 mack cx613 tuck that the headlights only stay on high beam or unless I hold the switch on the side I have replaced fuses, two new dimmer switches and on and off switch. They only stay on high beam when you are holding the passer switch on the side of signal  light switch

[Joey Mack]

Follow the wires along the frame to look for damage, also check connections of the hood harness. It is right in front of the steering box. It may be clamped to one of the mounting bolts.  The steer tire slings everything you drive over, right on to the plugs. Its also a pivot point for the hood. Start simple first.