headlights are not working . ground issue ? 1973 dart slant 6

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moparjon

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1973 dodge dart slant 6 . I just got this car a few days ago . The previous owner said he bypassed the alternator gauge by connecting the two wires that go to it together . He said it was because the gauge was causing a NO POWER condition as in none at all . is that possible ? . The Headlights are not working . i think it is a ground issue , but i am not sure .

With the HL knob pulled out to the first and second step , just one front parking light comes on steady , and both back lights and rear side marker lights come on . All other outside lights work normally with first step of switch except for the two front side markers . Same for second step , except with the right turn signal turned on , it stops blinking . The headlights do not come on . It is not the footswitch . The footswitch pigtail is showing power at all three terminals . Without footswitch attached . Both headlight pigtails are showing power to all three terminals . All are showing almost full battery power 12.27 + or - . That is not right . One "should" have no power for ground , correct ?

None of the dash lights light up either as far as i can tell .

The negative battery cable and connections and ground there all test good . I am suspecting where the other two wires come together where that attaches near the radiator , but , I didn't want to start cutting into them without ruling out other things .

Can it be the Headlight Switch ? ( i am looking for the extra one i have right now )
Would the cluster ground , or lack of , cause this full power symptom ?
Where are the grounds on a 1973 dart slant 6 , besides the one going from the firewall to the engine top ? and the rad area .
What else am i forgetting to check ? anything the previous owner might have unknowingly done while messing with the alt gauge ?

Thank you for your time and thoughts .
 
Check the dimmer switch, being on the floor they get a lot of abuse/dirt/corrosion.
 
Well you need to do some actual TESTING, not guessing.

FIRST if you do not have such, wander over to MyMopar.com and download both volumes of the 73 service manual, and while there, go to the wiring section at MyMopar and download the simplified aftermarket diagrams, which can be easier to follow

SOME OF those manuals got there because of some of the guys right here!!

Ammeters and the ammeter circuit can be a big problem. Read this article to find out the why


PART OF the reason your tail/ park/ etc lamps are working is that the headlight switch has TWO SEPARATE power sources

The power for tail/ park/ instrument lamps comes from a fuse in the panel.

But the HEADLIGHTS ONLY power comes direct from a splice in the black ammeter wire a few inches from the ammeter. That wire goes to a different terminal on the light switch, which has a circuit breaker built onto/ into the light switch.

When you pull the HL knob all the way out, the HL power goes down to the DIMMER SWITCH (as mentioned above. It is a simple 3 terminal, double throw switch. This means that with the HL switch "on" there are always two terminals of the dimmer that should be "hot"

If you have power to one terminal of the dimmer and no others, and operating the switch does not change things, then the dimmer switch is bad. If you have power at two terminals and no lights, the trouble is out in the engine bay

If you have no power at all at the dimmer, you have problems up under the dash, time to pull the light switch, and probably, the cluster

ENGINE BAY: After headlight power leaves the dimmer switch, high and low beam power goes out on separate wires through the bulkhead connector, around the fender to the headlights. Often, the headlights are BOTH grounded through ONLY ONE screw. Start by running along that harness and checking for ground screw(s) and making sure they are so

It is not unheard of that headlights can BOTH burn out!!!

If you had power at the dimmer, go out into the bay, and using your manual/ diagram, probe the bulkhead connector for the head lamp hi and low beam and see if you have power there. If so, move on to the headlights themselves
 
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67Dart273 said:
If you have power to one terminal of the dimmer and no others, and operating the switch does not change things, then the dimmer switch is bad. If you have power at two terminals and no lights, the trouble is out in the engine bay
67Dart273 said:
ENGINE BAY: After headlight power leaves the dimmer switch, high and low beam power goes out on separate wires through the bulkhead connector, around the fender to the headlights. Often, the headlights are BOTH grounded through ONLY ONE screw. Start by running along that harness and checking for ground screw(s) and making sure they are so
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Thank You . There is power to all three terminals at the dimmer switch . There is power at the inside and outside of the bulkhead on the high and low beam wires . It is close to full battery voltage 11 - 12+ volts . There is power at all three headlight terminals . Both sides . With and without headlights attached . Again , 11 - 12+ volts for each terminal ( all 6 ) . I tried a known good headlight and it didn't work .

I checked the ground screw you mentioned , but i am not sure i am doing that right . I tried the multimeter with one probe to the positive battery post and the other probe on the ground screw connection near the radiator . It shows 12+ volts . I didn't see any other grounds along the fender . Not sure what to do next .
 
I you have power and ground at the headlight connectors check the headlights
 
At this point you are either down to a ground issue or the headlights are bad. To check that, pull out either lamp a little so you can access the connector, with the headlamp still connected. With the HL switch on, clip your meter ground to the battery neg. to start with and probe the connector. 1 of 2 will have power at a time and the other is ground, so this can be confusing.

With HL power OFF you can first identify the ground terminal by probing the connector for continuity

Here is a headlight connector, BK is ground here

HL.jpg

Anyhow, one of the two "non black" should have power depending on whether the dimmer is in hi or low. So with the lamp connected, and lights powered on, if you show power on say, lo beams, and the ground is good, it is gonna be the lamp.

You can use your meter and "ohm" the lamp. All three pins show continuity to each other on a good lamp
 
If both lamps ARE bad, you may have an overvoltage charging problem
 
67Dart273 said:
At this point you are either down to a ground issue or the headlights are bad. To check that, pull out either lamp a little so you can access the connector, with the headlamp still connected. With the HL switch on, clip your meter ground to the battery neg. to start with and probe the connector. 1 of 2 will have power at a time and the other is ground, so this can be confusing.
Click to expand...

67Dart273 said:
You can use your meter and "ohm" the lamp. All three pins show continuity to each other on a good lamp
Click to expand...

Headlight connectors again showed power at all three terminals . Headlamps showed continuity on all three pins . so, lamps appears to be good .

Grounding Issue ? - I am having trouble deciphering the wiring diagrams . The Ground wires that "Y" together at the firewall . i went ahead and cut them off and separated them because the ends looked corroded . They seam fine though after peeling back the jacket a bit on each one . one makes the sound for continuity from the bulkhead in both the high and low beam connectors . The other one does not make the sound with the meter on either high or low connector . Does that other wire go somewhere else ? i can't figure it out with the diagrams . I just get headaches .
 
Don't know if this has anything to do with it . The wiring diagrams for "HEADLAMP GROUND" show something about a New York Horn . I bought this car in New York . Could that be any sort of possibility as far as grounding the lights goes ?

HPIM0801.JPG


HPIM0802.JPG


HPIM0803.JPG


HPIM0804.JPG
 
Horn should have nothing to do with it

If all three terminals of the connectors show power they are NOT grounded. One of the terminals is ground

You should be able to ID the black coming out of each HL connector. --if the harness has not been painted.
 
Look at the photo you posted of the two ground lugs. L9BK is the common ground for the HL. The H9 wire is the horn. Then look at the diagram I posted of the HL connector. The two blacks comeing out of that connector is the L wire ground. They jumper across so both HL end up grounding in one wire. If you can't find it, cut them off as pigtals, and ground them individually near the HL buckets
 
67Dart273 said:
L9BK is the common ground for the HL.
Click to expand...

Ok . I put an alligator clip lead , one end on the ground blade of the driver side HL ( still connected ) . I put the other clip on the bumper and both of the headlights came on . They are working properly . High beams come on .

I would like to try to find and fix the bad ground if its possible . I just don't know how to do that . Any suggestions ? Also , i don't know if its related because the previous owner messed with some things , but , it appears that none of the dash cluster lights come on . i will double check this when night comes . Definitely no high beam light and definitely no turn signal lights . He bypassed the ammeter . The temp and fuel gauges operate , but unknown if accurate . I will start with changing bulbs , but doubt all of them blew out .
 
moparjon said:
Ok . I put an alligator clip lead , one end on the ground blade of the driver side HL ( still connected ) . I put the other clip on the bumper and both of the headlights came on . They are working properly . High beams come on .

I would like to try to find and fix the bad ground if its possible . I just don't know how to do that . Any suggestions ? Also , i don't know if its related because the previous owner messed with some things , but , it appears that none of the dash cluster lights come on . i will double check this when night comes . Definitely no high beam light and definitely no turn signal lights . He bypassed the ammeter . The temp and fuel gauges operate , but unknown if accurate . I will start with changing bulbs , but doubt all of them blew out .
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You're simply going to have to do some manual back tracing of the ground blade in the headlight connector. Find the wire color on the ground blade connector and trace it back through the harness until you find where it attaches to ground.
 
^^Yup. You know where both ends are. It is black no 18 wire, one end is the eyelet where it's bolted to (I thought the radiator crossmember?) and the other end is at the headlight connectors. As I said earlier, you can unwrap the harness a few inches, and cut off enough wire back from the lamp connectors, to make pigtail(s) and then bolt them to the fenders near the HL buckets.
 
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