Car wont start unless door is open

-
ratty dart 340

ratty dart 340

Well-Known Member
Joined
Feb 8, 2022
Messages
238
Reaction score
91
Location
Colorado
Hey everyone. I have an interesting electrical and ignition issue.

So I have a 73 dart sport that now has a 360. We pulled it out of a field where it had been sitting for 20 years. We got it running and running pretty well. However, we recently replaced plugs, plug wires, dist. cap, new rotor, and coil.

We just now notices that the car only starts when the door is open. Which means the buzzer is buzzing and the dome light is on. I did further testing and realized that the dome light has no effect on when the car runs or not. Thats simple. There were to wires that went to the door switch. One for buzzer and one for dome light. However, when the buzzer is grounded, the car starts every single time. And when the buzzer is not touching anything, it doesnt start.

I followed a few wiring diagrams and cant figure anything out. I feel like its a short but im not sure how or why the car starts when the buzzer wire is grounded.



Thanks, Andrew
 
sounds like a security feature, whether it was intentional or not it might slow down a thief from starting your car and driving away
sorry I can't give any real input to your problem :lol:
 
Cuda Al said:
Does it stay running when the door is closed?


Alan
Click to expand...


yes it does. I was just testing arounf with seatbelt because i know they added some funky stuff in 74. I was trying to actuate the switch in the retractor and a dash light and different buzzer came on.
 
Isn't there a seatbelt interlock?
A switch under the hood to bypass?


Alan
 
The only year that is SUPPOSED to have the seat belt interlock is 74, easy to identify---look along the driver side fender apron for a small box about size of horn relay with a reset button. But that does not work as the OP describes. It "trips" and opens the starter relay yellow actuator wire from the key, so it just won't crank until the button is reset---or the owner (wiring) bypasses the reset

I cannot think off hand what in the world would inter--connect the courtesy/ dome/ buzzer to disable the start relay

I would start by taking a good look under the hood at the wires going from the start relay to the bulkhead, and then access the wiring of the ignition switch connector leaving the column--look for any signs of tampering, splicing, etc,

Look for any added non-OEM devices/ boxes both under hood and under dash

74 interlock reset:

1974 duster seat belt interlock module removal

bypassing interlock system

100_0894-jpg-jpg.jpg


16kx4d2-jpg.jpg
 
The electrical path "normally" for the start relay coil should be completely independent of any other circuit, here is how it works in 73:

The start signal for the relay comes off the "start" contact on the ignition switch--a dedicated, separate contact. It goes nowhere else. It feeds a yellow wire which goes directly through the bulkhead connector and to one of the two "flag" push on terminals on the start relay. Through the relay coil and out the second "flag" teminal, from that terminal a wire goes down the firewall, over the transmission, and connects to the center pin on the neutral safety switch, which is grounded in park or neutral.

NO PART of this circuit is (originally) interconnected with any other circuit in the car

In my mind the problem must be a pinched / damaged harness, or wires burned or melted from a short, or someone modified the wiring or tried to add a security system.

Once again if this is some odd late year 73 which has the seat belt interlock, even that goes to no other part of the wiring. The reset box simply opens the yellow "start" wire
 
67Dart273 said:
The only year that is SUPPOSED to have the seat belt interlock is 74, easy to identify---look along the driver side fender apron for a small box about size of horn relay with a reset button. But that does not work as the OP describes. It "trips" and opens the starter relay yellow actuator wire from the key, so it just won't crank until the button is reset---or the owner (wiring) bypasses the reset

I cannot think off hand what in the world would inter--connect the courtesy/ dome/ buzzer to disable the start relay

I would start by taking a good look under the hood at the wires going from the start relay to the bulkhead, and then access the wiring of the ignition switch connector leaving the column--look for any signs of tampering, splicing, etc,

Look for any added non-OEM devices/ boxes both under hood and under dash

Will do. I traced back the black wire that was used as the buzzer wire, and it leads to the single prong on that terminal in the bottom pic you sent. If that relay were to be bad, would that result in my problem?

74 interlock reset:

1974 duster seat belt interlock module removal

bypassing interlock system

View attachment 1715879932

View attachment 1715879933
Click to expand...
 
67Dart273 said:
The electrical path "normally" for the start relay coil should be completely independent of any other circuit, here is how it works in 73:

The start signal for the relay comes off the "start" contact on the ignition switch--a dedicated, separate contact. It goes nowhere else. It feeds a yellow wire which goes directly through the bulkhead connector and to one of the two "flag" push on terminals on the start relay. Through the relay coil and out the second "flag" teminal, from that terminal a wire goes down the firewall, over the transmission, and connects to the center pin on the neutral safety switch, which is grounded in park or neutral.

NO PART of this circuit is (originally) interconnected with any other circuit in the car

In my mind the problem must be a pinched / damaged harness, or wires burned or melted from a short, or someone modified the wiring or tried to add a security system.

Once again if this is some odd late year 73 which has the seat belt interlock, even that goes to no other part of the wiring. The reset box simply opens the yellow "start" wire
Click to expand...
67Dart273 said:
The electrical path "normally" for the start relay coil should be completely independent of any other circuit, here is how it works in 73:

The start signal for the relay comes off the "start" contact on the ignition switch--a dedicated, separate contact. It goes nowhere else. It feeds a yellow wire which goes directly through the bulkhead connector and to one of the two "flag" push on terminals on the start relay. Through the relay coil and out the second "flag" teminal, from that terminal a wire goes down the firewall, over the transmission, and connects to the center pin on the neutral safety switch, which is grounded in park or neutral.

NO PART of this circuit is (originally) interconnected with any other circuit in the car

In my mind the problem must be a pinched / damaged harness, or wires burned or melted from a short, or someone modified the wiring or tried to add a security system.

Once again if this is some odd late year 73 which has the seat belt interlock, even that goes to no other part of the wiring. The reset box simply opens the yellow "start" wire
Click to expand...
when we got the car, we noticed that this connector had been fried. Also the owner before us was mr.jenkyPants so a lot of things are unplugged but seem to have no where to go.
image.jpg
 
Just found another short of wiring. I’m not sure if this is what you meant when you said the wire runs on top of the tranny. It’s a group of wires joined by a connector. It’s three wires in total. The wires are completely exposed and possibly shorted on the valve cover or something else.
image.jpg
 
ratty dart 340 said:
I’m not sure if this is what you meant when you said the wire runs on top of the tranny.
Click to expand...
Yes.
The middle one goes to the neutral safety switch. It allows the starter relay trigger to ground when the transmission is in P or N.
The side wires connect to the reverse light switch. One is hot whenever the key is in run, but not start.
 
ratty dart 340 said:
when we got the car, we noticed that this connector had been fried. Also the owner before us was mr.jenkyPants so a lot of things are unplugged but seem to have no where to go.View attachment 1715879974
Click to expand...
You likely need to splice the wires from that white connector individually and eliminate it. Redfish, on here, has written about it. That connector was added "at some point" (year) to make it easier for factory to connect engine to bay. Older cars don't have it, and it is a BIG failure point
 
Mattax said:
Yes.
The middle one goes to the neutral safety switch. It allows the starter relay trigger to ground when the transmission is in P or N.
The side wires connect to the reverse light switch. One is hot whenever the key is in run, but not start.
Click to expand...
Explain further, the neutral/ reverse switch has 3 terminals and two switches. The center pin is switched to ground in park/ neutral and goes to the starter relay for neutral safety, allowing the siwtch to activate only in those two shifter positions. The outer two are reverse lights, so the 2nd and 3rd wires in that harness are power to the reverse switch, and the 3rd wire feeds off TO the reverse lights. It routs up through the bulkhead, down to the left side kick panel connector, and on to the rear harness and reverse lamps

I'm still not seeing anything that relates specifically to your problem. Actually there "should" be nothing damage wise in the engine bay that could cause the start problem, as there is no courtesy lamp wiring in the bay. The comments I made earlier were more "general" and also if someone had hacked some anti theft device in.
 
ratty dart 340 said:
There is also this bulky black wire that appears to have gotten very hot at some point.
Click to expand...
Could be the alternator output wire. That supplies power from the alternator to everything when the engine is running. If there are a lot of electrical items running at the same time and/or the battery is recharging at high rate, any weak spote in that line can overheat.

labelled 'R6' in the drawing
upload_2022-3-1_20-43-12.png
 
67Dart273 said:
You likely need to splice the wires from that white connector individually and eliminate it. Redfish, on here, has written about it. That connector was added "at some point" (year) to make it easier for factory to connect engine to bay. Older cars don't have it, and it is a BIG failure point
Click to expand...

And it has that R6 in it. Definately should make that a well spliced connection.
upload_2022-3-1_20-49-16.png


R6 = Alternator Output
J2 = Ignition Run (ignition ECU, Ballast resistor, Alternator field feed and Voltage regulator sensing)
J3 = Ignition Start
R3 = Alternator field to voltage regulator.
G is probably gages (temperature, oil)
 
67Dart273 said:
I'm still not seeing anything that relates specifically to your problem. Actually there "should" be nothing damage wise in the engine bay that could cause the start problem, as there is no courtesy lamp wiring in the bay. The comments I made earlier were more "general" and also if someone had hacked some anti theft device in.
Click to expand...
Good point.
Maybe something to do with how the buzzer ties in with the key switch.
ratty dart 340 said:
However, when the buzzer is grounded, the car starts every single time. And when the buzzer is not touching anything, it doesnt start.
Click to expand...
 
Mattax said:
Good point.
Maybe something to do with how the buzzer ties in with the key switch.
Click to expand...
Yes. That’s the best bones most simplistic reason. We found three more shorts. All of which don’t fix our buzzer/ignition problem.

we are still looking but this is a very tricky wiring issue.
 
Does the buzzer sound when the circuit is closed at the left door switch?
upload_2022-3-1_21-32-9.png


If not, then maybe its not connected to buzzer.
CI 5 is steering column connector.
Could be a pinch or a miswire there?

On the inside there's two wires for the start.
Ignition Start (J3) is Brown. That does not effect the starter.
Starter Relay trigger (S2) yellow. That does not effect the ignition.

In the engine compartment, for the starter relay to close, the neutral safety switch must ground.
The only way it could get involved with interior stuff again is getting cross connectec with those reverse light wires.
That is, unless something else was modified.

Might want to begin with the column connector, and then do some continuity checks to see what else may have gotten connected in to those circuits that shouldn't be.
upload_2022-3-1_21-45-26.png



Another check might be to disconnect the NSS wire at the relay.
Temporarily run a jumper to ground. See if it starts with the door closed.
if so, then you know it relates to the NSS wire.
 
This is really easy. Open the door, get in, start it up, close the door and go.
 
You must log in or register to reply here.
-

Back
Top