Headlights & Instrument Panel Question

Have kind of an odd electrical thing with my 72 AMX.

Check to see if you have headlight delay. If the box is bad, it can be removed, by swapping the delay box wiring connection to the switch, with the wiring harness connector at the box.

Like Mopar_guy stated...

Since it is a small black wire at the left mounting hole of the instrument light assembly. It is a eyelet style and can break off, as it loops through a small opening between the large panel frame and the panel light assembly. This mostly depends on how much work has been done in the cars past with the instrument panel, or wiring umder the dash. That ground wire could have been tapped for shared ground with another accessory, like a powered FM signal booster, for example. If that is the case, some times the splice makes the wire weak by years of vibration. You can probably verify without taking the instrument panel out, by removing the bottom section of the switch panel, and looking for the black wire that should be seen coming from the left part of the switch panel out to the wiring. Also you may see the head light delay box near that area and may obstruct view, if equiped.


The instrument lights are on a sheet metal frame, which has no ground to connect with on the large ABS structure, thus the wire connection is needed. Some indecator lights have their own ground and will function, but all others require that ground connection.

bigbad69 wrote: Given the symptoms, I would suspect the switch is faulty. The switch routes power. The ground is at the lamp. There is no need for a good ground at the switch.

I hear ya and that's my first thinking - but why does AMC have a ground wire to the headlight switch???
My Eagle has a factory ground wire going to it from the harness. It also says the wiper switch is "grounded to headlight switch". 

Every Eagle I've ever taken apart has the headlight switch grounded. 
I agree with bigbad - it's a switch, not an electronic device. It takes battery power and routes it to the proper lighting circuit - there's nothing that should ground through the headlight switch. there are no lights IN the switch. I've had people say "it's for the indicator light in the switch" - there's no such light in the switch. 
The dimmer is a simple rheostat - doesn't need a ground. It's a variable wire-wound resistor. If you grounded it you'd make things get hot. The courtesy lights in my cars have their own grounds.

(And for onlookers - NO, it's NOT cluster or dash lights! Those have their own ground. The indicator light next to the switch, the dome lights, cluster/instrument lights - ALL have their own ground and none should need to ground back at the headlight switch - and yet AMC grounded the headlight switch.)

What it IS for, and for this only, is the DOME/courtesy lights (if you have the latter, if not, then for DOME lights only)
That is the only purpose. So if you leave the ground off everything will function just fine - EXCEPT in full CW position, the dome light will not come on. 
Dome is hot all the time, the door jamb switches GROUND the dome light to turn it on. 
The headlight switch does the same thing. Turn it full on (rotating) and it turns the dome light on by grounding it. 
Otherwise PANEL lighting, instrument lighting, headlights, everything else will work. 

on Javelin the headlight switch must be to at least first position for the panel light switch to power the cluster lights - it gets power from the blue wire coming off the headlight switch. this way when you turn the main light switch off it shuts off the panel light. You can leave the panel light switch on to either of the "on" positions and just let the headlight switch control the lights.
So you can have headlights without panel lights in any AMC car - either turn full CCW on non-71-74 Javelin or leave the panel light switch off but you can't have panel lights without having the headlight switch on to one of the on positions. 
And the ground - if you leave it off all that won't work is the dome or dome/courtesy lights. Panel lights have their own ground but dome works by the switch grounding it because they are hot all the time.

Edited by billd - Jun/21/2019 at 9:34am