Stuntman_Bill

Has anyone had experience with the built-in CB in a '66-'67 headlight switch failing or beginning to fail? As I keep struggling with my Charger's cold-blooded rough idle, the breaker has tripped out on me a number of times. Not sure why, I guess due to voltage surges, although you'd think the regulator would catch that. Anyway, the breaker in my switch has refused to quickly reset a number of times, leaving me stranded on the road with no headlights. At least three times it has not reset until the next day, which sounds like a failing breaker to me. Since the switch is a sealed unit I guess there's no choice but to replace it, which is a pain because a replacement switch is fifty bucks. I'd just like to do a sanity check before I pay for another expensive replacement part. Does that sound right, headlight switch CB failing to reset means dying breaker so must replace switch?

RacerHog

Here are a couple of good reads....
http://madelectrical.com/electrical-tech.shtml

Stuntman_Bill

Well, now the headlight switch appears to have partially or fully burned out, and it cost me a ticket last night for trying to limp my sled home with the headlights out. (I wasn't driving far.) I suspect this is a symptom of the more serious endemic, systematic disaster that is the electrical system in its current state. I pulled the switch and it is clearly a fairly new replacement, so likely the headlight switch has been burned out previously due to whatever one or several glitches or whatever are causing my problems. In short, I can't just replace the switch because evidently a previous owner did just that, and I'll keep burning out switches until I figure out the root cause. So pardon a slew of follow-up questions but I really, really need some seasoned advice from Mopar guys:

--Has anyone got a schematic of the internal wiring of a '66 Charger headlight switch? I cannot tell whether the integral circuit breaker protects/is in circuit with all of the output leads or just the headlight ("H" lug) output. When the CB was tripping out previously, only the headlights would go dark. I pulled the switch out today and now the switch shows no continuity between the input feed ("B1" lug) and any of the output leads, in any of the three switch-pull positions, or regardless of whether the accessory feed dimmer switch is on. In other words, completely dead.

--Is the headlight switch supposed to be purposely grounded to the chassis ground? There is a tab at the back of the non-original replacement switch which clearly appears to be a switch-case ground lug. Pics of OEM switches do not have this lug. None of the Mopar wiring diagrams show an 8th lead, but it sure looks like an added switch-case ground intended to keep the switch from floating above chassis ground. Well, this tab was not connected as a discrete ground, and because the dash was repainted I suspect the switch was floating un-grounded due to lack of contact between the switch shaft and the dash metal.

--It's pretty much a straight-through connection between the alternator output and the input feed of the headlight switch. So, yeah, rough-running engine doubtless generating lots of voltage spikes, feeding directly into a headlight circuit breaker floating without a good ground...I guess that would fry the switch. What I don't understand is why the alternator regulator did not protect the headlight circuit, because if it is faulty there are a lot of other unfused feeds that could fry.

Yeah, the headlight switch is definitely looking like a mineshaft canary in this scenario, and if I can't figure out the real problem I'm just going to fry another switch.

Racerhog, that link did lead to an article about ammeter feed problems in old Mopars, and I suspect that that may be one of the root causes to my electrical woes. I can't believe that Mopar designed all the non-ignition load to flow through the ammeter! Yes, I understand why that's necessary if you are using amps pulled rather than voltage to measure alternator output, but it's still a horribly antiquated way to design your automotive electrical system, and I don't recall seeing that in any of the 60's Ford and GM iron I've worked on.

TATZ

I HAVE TWO NEW SWITCHES AND THE SAME PROBLEM. THE CB BREAKS ON AND OFF AND THE HEADLIGHTS GO UP-DOWN-UP-DOWN AS OFTEN AS THE BREAKER SEPARATES AND CONTACTS. IT'S A QUESTION OF WHAT IS CAUSING THE BIG DRAW IN THE FIRST PLACE THAT OVERLOADS THE BREAKER. I FEAR A SHORT IN THE WIRING BETWEEN THE SWITCH AND THE BULBS, WHICH WILL BE VERY HARD TO FIND. I AM FIRST TRYING NEW HEADLIGHT SEALED BEAMS, THOUGH THEY BENCH TEST OK. THEY ARE 50-SOME YEARS OLD??

BTW, I HAVE REVIEWED THE RELAYS AND AM "SURE" THEY ARE OK. SINCE THE MOTORS GO BACK AND FORTH AS THE BREAKER WORKS ON AND OFF, LOGICALLY, THE RELAYS ARE WORKING AS THEY SHOULD.

I HAVE NOT MODIFIED THE HEADSLIGHT SWITCH PIGTAIL. POWER GOES TO P, AND THEN TO H AS THE HL SWITCH IS PULLED ALL OUT. THERE IS A SEPARATE POWER WIRE THAT GOES TO D FOR THE DOME AND INTERIOR LIGHTS. AM I RIGHT IN THAT? UNLESS I PUT POWER TO D, THE DOME LIGHTS ETC., DO NOT WORK. I TOOK THE OLD HEADLIGHT SWITCH APART. I DON'T SEE HOW D WOULD OVERLOAD THE H CIRCUIT.

Kuvasz101

Ground, ground and clean and recheck grounds. Many times an excessive positive draw such as yours is caused by faulty grounds. Are your headlights or one headlight amber in color? Do your lights dim excessively on idle and brighten noticeably on revs? If so these are all signs of a bad ground.

TATZ

THANKS. WILL CHECK. AND RE-CHECK.