Electrical assistance needed

1971 - 1974 Mopars

  1. 71GTX440

    71GTX440 Well-Known Member

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    I did not do a continuity switch. I ordered a new one for a few dollars. Easy to order and easy to replace. I did replace the left door switch and installed a new head lamp switch. I also ran continuity across all the wires in the circuit for the dome lights.
     
  2. 71GTX440

    71GTX440 Well-Known Member

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    Sorry for the late response. I did check for continuity on both switches. Both did not pass. I may be doing it incorrect though. Should zero out when in the open position. Mimicking the door closed position. I have new switches due in this week.

    On a side note, I did get all my dash lights to work :) Replaced the head lamp switch (rockauto.com) and grounded the switch body to the dash harness grounding point.
     
  3. 72RoadrunnerGTX

    72RoadrunnerGTX FBBO Gold Member FBBO Gold Member

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    Did you verify the correct bulb (1004) is installed in the dome light. Other two contact bulbs in that socket will not be controlled by the dome light grounding circuit, will have one filament be on all the time.
     
  4. 71GTX440

    71GTX440 Well-Known Member

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    I can go buy a 1004, however, if the ground spots on the door jambs control the ground, any two post bulb would work regardless of the number of filaments. Power would be an open circuit when doors are shut, thus turning bulb off and circuit would be closed causing the light to go on when doors are open.

    Let me know if I am missing on this thought
     
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    • 72RoadrunnerGTX

      72RoadrunnerGTX FBBO Gold Member FBBO Gold Member

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      The 1004 is the only two contact bulb where the bulb socket sleeve is not part of the electrical circuit. The 1004 is the ONLY bulb type for that application. The single filament in the 1004 does not ground through the sleeve. Most all other two contact bulbs do, and when in that socket, one filament will be grounded constantly if the dome housing is screwed to the roof support. To verify, unscrew the dome light housing from the support and let it hang, light goes out, wrong bulb type. Light stays on, keep looking at the wiring for the yellow circuit being grounded somewhere.
       
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      • 71GTX440

        71GTX440 Well-Known Member

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        Ahh, thank you. Was unaware it worked this way. Hard to see that from the FSM and schematics. Your knowledge is invaluable and I appreciate the constructive input.
         
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        • khryslerkid

          khryslerkid FBBO Gold Member FBBO Gold Member

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          Is there other courtesy lights inside the car that share the same circuit? Console, rear pillar, glove box?
           
        • jimt1971rr

          jimt1971rr Well-Known Member

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          Your meter should show a 1 in the circuit open position (door shut), and a 0.00 in the circuit closed (door open) position.
           
        • 71GTX440

          71GTX440 Well-Known Member

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        • 72RoadrunnerGTX

          72RoadrunnerGTX FBBO Gold Member FBBO Gold Member

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          Only the diagrams in the factory service manuals for the specific model year in question will be actuate. Most third party wiring diagrams don’t show slight variations year to year. The three pin left jamb switch is correct for ’71, with a two pin switch for the right door. Only one wire (yellow, no trace) in each switch controls the dome light by the way, second one in each switch is the ignition lamp timer circuit, third one on the left switch is the buzzer circuits (lights on & key in switch)
           
        • 71GTX440

          71GTX440 Well-Known Member

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          Perfect, that is how it is all wired in. Heading to the store to get a 1004 bulb for the dome light this afternoon. Now on to the elephant in the room. Car will not start! started a few days ago when I went tooling around, now, nothing. Just the wiper motor click.

          13 VDC at the battery, 13 VDC at the ignition relay post, 13 VDC at bulk head red wire, 13 VDC at the top post on the starter solenoid. Ground at ignition relay has continuity, yellow (exciter) wire has 4.95 VDC at ignition relay when key is turned, 0 VDC at the solenoid brown wire at the ignition relay at all times. Bought another relay from Advanced, same issue. Bought a relay at O'Reilly's, same issue.

          Thoughts on this issue? All lights work, car wont start up.
           
        • Mopars & Missiles

          Mopars & Missiles Well-Known Member

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          Your start problem is right there in front of you. You must have 12V on the "yellow" wire at the relay when you turn the key. 5 volts is not enough to energize the relay. This is the 'start' command from the ignition switch to the relay. The brown wire is the 'ground' for the relay from the NSS and also must be present for the starter relay to work.
           
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          • 71GTX440

            71GTX440 Well-Known Member

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            I haven't wired anything new in the system, where do you think I should be looking for the issue at?
             
          • 71GTX440

            71GTX440 Well-Known Member

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            I found the issue. Took the drivers kick panel off and found a connection where the previous owners had wired in a wire to provide the power source for some after market gauges (vacuum, etc). When I pulled this connection apart and ran the main HL green wire to the floor switch, presto. Instant start up :)

            I did like the extra gauges having lights, any ideas where to pick up an after ignition 12V source under the dash that wont kill the exciter wire for the ignition relay?
             
          • 72RoadrunnerGTX

            72RoadrunnerGTX FBBO Gold Member FBBO Gold Member

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            There is an orange molded three-way bullet connector tap on an orange wire meant specifically for adding illumination lighting, connect your gauge lighting there. Left side of dash harness, near heater control.
            [​IMG]

            The connection you found on the headlight circuit shouldn’t have anything to do with the starter relay. I’d take a close look at the Molex connector on the ignition switch wiring, common weak point.
             
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            • 71GTX440

              71GTX440 Well-Known Member

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              Works perfect, your information was spot on. Put a new bullet terminal end on and plugged in to the orange three-way. All lights work and car fires right up!
               
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