Headlamp switch issue?

[b5cuda]

Hey everyone, I'm working on getting my car road ready and have an issue with turning on lights. Nothing happens when I turn switch to parking lamp position. When I slide the switch up slowly, halfway between parking light and headlamp position I hear a relay click and I get dash, park, and tail lamps on. Slide the switch all the way to headlamp 'on' position and everything goes off. I have tried three used switches, all give same result. Do I have three bad switches, or something else? FWIW, I have Rob's (crackedback) harness installed. Appreciate any tips.   

[Bullitt-]

 My guess is there is another issue, perhaps a failure of the floor mounted dimmer switch or wiring connector. 

[Jay Bee]

Since crackedback's harness is plug 'n play, did you try to unplug 'n play just to see?

[b5cuda]

Aha, when I applied a grounded testlight to the lead to headlamps, they lit up! So, I have a grounding issue on the headlamps to address. Still no dash lights on "headlamps on" but at least I now have headlights. One step closer. Thanks guys!

[Dakota]

For a 70 Challenger, if i remember correctly the headlight harness ground goes to driver side support for the radiator (engine side) near the battery.  I can't speak to how it was done on other years. 

[b5cuda]

Thanks, yes that's where I found a loose ground and now headlamps work. Still some issues, I don't get "park" lights (dash, front park lights, tail lights) until the switch is 3/4 up (between park and headlight position, and when I put the switch all the way up I get headlamps but lose dash, park, and tail lights. I want to think it's the headlamp switch, but I've tried three different (OEM) switches and each does the exact same thing. Anyone else had same situation?

[dylo]

The headlight switch shares a black wire from your dimmer knob. I would try and bypass that dimmer and see if it works.

[dodj]

While not factory, I would recommend running a ground wire from the switch mounting plate to frame. Ensures a good ground.

[b5cuda]

Thank you guys, I appreciate the tips!