Headlight Switch Continuity Question
 

My dash lights, side marker lights, and tail lights haven't been working for a while so I've began tackling that beast. I figured it was most likely the headlight switch since the fuse and grounds where all fine. The switch was in fact bad, so I purchased one from Napa to replace it. Once installed it still didn't work... so with my satellite wiring diagram I checked all the wires for power and continuity. I was getting power in from the (Black) power feed, and everything else checked out until I check the headlight switch. Knowing what wire went where, I checked for continuity on all poles in the proper switch positions.... I was getting no continuity from the power to anything except the (Green) headlight power feed. I tried this with the switch pulled out halfway (should have functioning parking lights and dash lights) and with it all the way out (should have illuminated parking, dash, and headlights) instead I just had headlights. I figured I bought a defective switch so I went back to Napa and exchanged it for another one. When that one came in I tested it at the store for continuity.... it didn't have it either! So my question to you all knowing mopar fellas is... Shouldn't I have continuity in those places, or am I missing something somewhere? Here attached is a wiring diagram I drew up of the headlight switch... Once again, no continuity from the (Black) power feed to anything except the (Green) wire that goes to the headlights. Any help would be greatly appreciated. Thanks!

First, if you don't happen to have a service manual, there's one you can download for free posted over here:

http://www.forabodiesonly.com/mopar/...al%2C+download

There are free electrical diagrams posted here:

These are not the original shop manual diagrams, are sometimes helpful, sometimes not


http://www.mymopar.com/index.php

Should be for your 72 Satellite:

http://www.mymopar.com/downloads/1972/72SatelliteA.JPG

http://www.mymopar.com/downloads/1972/72SatelliteB.JPG

First, the black is power coming into the switch from a splice in the harness, it is NOT FUSED so be careful. this line depends on the switch mounted breaker for protection, and ONLY powers the headlights

The switch is essentially THREE switches in one
===============================
The big black power ONLY feeds the headlights, you already found that

===============================
The pink is fed power FROM the tap in the glove box which in turn comes FROM the cigarette lighter and is fed from that 20A fuse

This pink (B2 on the switch) means "battery 2" and feeds power to the tail and park circuit
===============================
The tan you show with a 5 amp fucomes from the fusebox, through the fuse, and comes back OUT the fusebox (E2-18O)

The shop manual shows this junctions at the radio connector where it splits off, including to the turn signal flasher. This convoluted mess is fed from the 20A Radio fuse

So far as I know, the only thing that 5A fues does is to feed the dash lamp dimmer
================================

So the switch labels are nearly self explanetary:

B1 is "battery 1" and feeds through to H to the dimmer switch / headlights

B2 is "battery 2" and feeds through to R to the park and tail. R meant "rear" and the unused "P" used to feed the park, before they decided to bring parking lights on with tail lamps'

I think T is actually I and is the power from the 5A instrument fuse, feeds the variable dimmer and out on D for "dimmer output" to the dash lamps.

So with the switch OFF you should have power at THREE terminals, B1, B2, and I (tan)

Pulling the switch out to "park" you should have the above plus R should be hot, and D should be hot if turned up

Obviously pulling out to headlights, H should be added hot.

Refer to the screenshot (out of the 72 manual download) of the fuse list



The 20A "misc" fuse powers much of the instrument and glove box lamps and the cigar lighter

You have the 5A "instrument" fuse

So you have THREE separate circuits inside that switch.

The big unfused BLACK only feeds the headlights through the switch mounted breaker

The B2 terminal feeds the tail/ parking lights

The 5A fuse for instrument, which in turn is fed from the Radio fuse feeds the variable dash lamp dimmer.

http://i56.tinypic.com/23vklkj.jpg

Ahh-haaaa....That would make a little more sense. Thanks 440roadrunner for all the work you've done tracking that down..good for you!!! I actually already had the 72 Satellite wiring diagram already and is how I traced all this down in the beginning. I guess I read it like the B1-BLACK powered everything instead of power coming also from the B2-PINK. So if you were me and still not getting dash lights or parking lights, would you start by tracing back that PINK through the lighter/glovebox and then the RED on back to the fuse block? It also looks like those two are also grounded...that might be a place to start. Thanks again!

Yep. I didn't look up what all the pink line is on, but it appears to be a fair amount of stuff. Basically, with the key off, "some" of the fuses should show power on both sides of the fuse. With key ON in "run" they all should show power except that 5A instrument fuse, and it should be hot on both sides with the headlight switch in either park or full on.

Just as an update...I'm back in buisness now with the whole lighting thing. Thanks to 440roadrunner for all your help. After installing in my headlight switch today I traced back that Pink and Red wire discussed above, and found out what had been causing my problems all along. In the past, I would occasionally get a blown fuse, before eventually leading to a metled part of the headlight switch harness. After tracing it back I found that the connector came off the back of the cigarette lighter and was shorting out every once in a while on the back of the dash. So anyways... that all fixed and I can now drive at night!!

Very good. I can still vaguely remember years ago a sailor at Miramar had a Mopar kept blowing a fuse, and it turned out that something? Corrosion, ? in the lighter would cause it to blow that fuse. He'd chased his tail for over a month trying to find it.