1974 Plymouth Duster Project

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Dustin Mitchell

Active Member
Joined
Sep 14, 2021
Messages
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Location
Moore, Ok
Hello all. Coming in from Oklahoma with my '74 Duster 318 that I'm working on. Basically trying to get it running. I have a bit of electrical work to do and a bunch of other stuff. You know what they say about eating elephants...

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First question, "Do you have a service manual?" If nothing else the 74 electrical is much different than 73.

You can download the 73 manual free from MyMopar. I posted the 74 wiring section which you can download

Go here
Free service manuals

Go down to post 64, and click the black icon and "save as".

Also go to MyMopar and download the free 2 page 3rd party diagrams. These are NOT complete and do NOT show all options or connectors but they can be easier to follow:

Wiring – MyMopar

Click on 1974 and unzip them. I have no idea why they chose to post them in that fashion, they used to be individual files

IF YOU HAVE NOT done so, bypass the annoying seat belt interlock. This is the "reset" box under the hood and has a button on the can. Permanently jumper the two "yellowish" wires together

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Also please read the MAD article about problems with the ammeter circuit and the bulkhead connector:

There are other ways around this but the article gives a good overview of how and why this gives trouble, as well as a great simplified power distribution diagram

Catalog

Last but not least look for a WHITE connector under the hood. This should be the only white connector there, and connects the harness section for the engine to the rest of the car. They are subject to failure, especially with the high current wiring going through it Best thing is to just permanently splice the wiring and do away with the connector. Earlier cars did not have them

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First question, "Do you have a service manual?" If nothing else the 74 electrical is much different than 73.

You can download the 73 manual free from MyMopar. I posted the 74 wiring section which you can download

Go here
Free service manuals

Go down to post 64, and click the black icon and "save as".

Also go to MyMopar and download the free 2 page 3rd party diagrams. These are NOT complete and do NOT show all options or connectors but they can be easier to follow:

Wiring – MyMopar

Click on 1974 and unzip them. I have no idea why they chose to post them in that fashion, they used to be individual files
Thanks for the information!
 
First question, "Do you have a service manual?" If nothing else the 74 electrical is much different than 73.

You can download the 73 manual free from MyMopar. I posted the 74 wiring section which you can download

Go here
Free service manuals

Go down to post 64, and click the black icon and "save as".

Also go to MyMopar and download the free 2 page 3rd party diagrams. These are NOT complete and do NOT show all options or connectors but they can be easier to follow:

Wiring – MyMopar

Click on 1974 and unzip them. I have no idea why they chose to post them in that fashion, they used to be individual files
One thing I'm having some difficulty with is getting the Painless Wiring harness matched up to the existing steering column Wiring. It's been a bit of a headache. Some of you may find it to be child's play and it probably is! It's just been years since I've had an old Mopar. Was 18 when I had my '73 Dart Swinger and I was so familiar with the wiring then. I'm kinda lost now.
 
I think Painless leaves out one wire. Pay attention to the IGN1 (ignition run) and IGN2 (coil bypass) which is missing I think. If you read that wiring pdf which I created from the original manual, there's charts on past the diagrams which show the various connectors including the ignition switch connector

ignswitch.jpg


S2. 12Yellow is start--feeds off through the firewall connector to your start relay
Q2 12BlacK is the main feed going off to the fuse panel ACCESSORY buss
J2A-12Dark BLue is the "ignition run" goes out to engine bay and feeds ignition system. THIS IS LIKELY different with Painless I think they have a separate wire for "alternator exciter"
J3-12Brown is the ign2 coil bypass circuit. If you are NOT using an ignition with a coil resistor, using such as MSD etc, jumper the J2 and J3 together THIS IS likely the missing wire with Painless not sure

J1-12Red is the main feed power coming INTO the switch

E2-20 Orange May or may not be used. This is dash dimmer controlled panel lighting going to the shift quadrant if column shift

M16-20BlacK
M16A-20BlacK These are the "key in" switch mechanism for the little "key" light and buzzer
 
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This is absolute gold. I somehow missed the pictures posted before, but see them now. Everything you've posted has helped me out tremendously already. I greatly appreciate it.
 
If you need more just post back here. There's some awesome guys on this board

I did not realize at first you were going Painless so the connector and reset I showed can "both go away." Also since you are going Painless I'd NOT try to use a bulkhead connector at all. If you pull it out and look at it, you can easily cut/ file a plate which will snap back in with the original clips and gasket, then just use the (should have) the big Painless grommet and run the wires straight through. I would NOT try and hook up the ammeter.

There's an old old thread on here gives ideas on converting an ammeter to a voltmeter. I don't think the Sunpro gauge is available any more, but still some great ideas in hhere. Read through, it covers several different cluster styles

Ammeter to Voltmeter...who does it?
 
I think Painless leaves out one wire. Pay attention to the IGN1 (ignition run) and IGN2 (coil bypass) which is missing I think. If you read that wiring pdf which I created from the original manual, there's charts on past the diagrams which show the various connectors including the ignition switch connector

View attachment 1715791133

S2. 12Yellow is start--feeds off through the firewall connector to your start relay
Q2 12BlacK is the main feed going off to the fuse panel ACCESSORY buss
J2A-12Dark BLue is the "ignition run" goes out to engine bay and feeds ignition system. THIS IS LIKELY different with Painless I think they have a separate wire for "alternator exciter"
J3-12Brown is the ign2 coil bypass circuit. If you are NOT using an ignition with a coil resistor, using such as MSD etc, jumper the J2 and J3 together THIS IS likely the missing wire with Painless not sure

J1-12Red is the main feed power coming INTO the switch

E2-20 Orange May or may not be used. This is dash dimmer controlled panel lighting going to the shift quadrant if column shift

M16-20BlacK
M16A-20BlacK These are the "key in" switch mechanism for the little "key" light and buzzer
One more thing that's confounding me. I hate to ask a bunch of questions here, and set me straight if I am. But, I also need to know how to wire up the instrument panel. I believe I'm missing a connecter that plugs into the back. It's the round array of male connector tangs. And also a battery hot and ground connects to the right of those terminals? Or is that the ammeter terminals which I won't need? Thanks again.
 
One thing I noticed especially with American Auto wire probably with most is they're trying to do a Chevy universal fit kind of deal..
 
If you need more just post back here. There's some awesome guys on this board

I did not realize at first you were going Painless so the connector and reset I showed can "both go away." Also since you are going Painless I'd NOT try to use a bulkhead connector at all. If you pull it out and look at it, you can easily cut/ file a plate which will snap back in with the original clips and gasket, then just use the (should have) the big Painless grommet and run the wires straight through. I would NOT try and hook up the ammeter.

There's an old old thread on here gives ideas on converting an ammeter to a voltmeter. I don't think the Sunpro gauge is available any more, but still some great ideas in hhere. Read through, it covers several different cluster styles

Ammeter to Voltmeter...who does it?
Absolutely. Basically what I have is 98% Painless harness and maybe 2% factory wiring. Basically what's left is from the steering column. And yes, the seat belt interlock is long gone! As well as the bulkhead connector. It is definietly not being used and I have the Painless harness running straight thru the firewall.

Thanks for the heads up on the ammeter. I will definitely look into replacing that with a voltmeter.

At this point, what I need to do is get starting/charging/instrument panel wired up and I believe I'm good to go.
 
One more thing that's confounding me. I hate to ask a bunch of questions here, and set me straight if I am. But, I also need to know how to wire up the instrument panel. I believe I'm missing a connecter that plugs into the back. It's the round array of male connector tangs. And also a battery hot and ground connects to the right of those terminals? Or is that the ammeter terminals which I won't need? Thanks again.
If you don't have the original instrument connector, put a "want" in the sale/ want ads and a member likely has one. You can do that another way, tho. It is fairly easy to solder pigtails to the board traces, ignore the original connector, and just use whatever you can scare up, like a Molex style connector

AND ON the instrument cluster.......

What are some of the "usual" troubles with them, another old thread:

Printed circuit pins repair

Generally:

If you use the original connector, inspect and solder/ repair the pins, as they are crimped to the board and can lose electrical connection

Instrument regulator/ limiter.......replace with a solid state one like RTE and solder jumpers across from the board traces to the connector fingers as shown in the thread above

Gauge studs lose connection. Consider replacing the "fake nuts" and loosen/ tighten them a few times to "scrub" the board traces clean

It would be wise to "jig up" the board and test the gauges for accuracy. You need test resistances for that:

c-3826-jpg-jpg.jpg


If you have the fuel tank out, an extra sender, or an appropriate rheostat, you can set it with an ohmeter to the above resistances to test. The guage tester goes from the sender connection on the gauge to ground and you must feed the gauge power through a good gauge limiter/ regulator

Clean up and inspect the lamp sockets, buff clean the connection prongs on the sockets, bend as necessary, and clean the PC board, and replace bulbs. Some guys use LEDS but there are many brands and some do not play well with the dash dimmer control Also most LEDs are polarity sensitive. You will not blow them up, they just won't light if reversed
 
If you don't have the original instrument connector, put a "want" in the sale/ want ads and a member likely has one. You can do that another way, tho. It is fairly easy to solder pigtails to the board traces, ignore the original connector, and just use whatever you can scare up, like a Molex style connector

AND ON the instrument cluster.......

What are some of the "usual" troubles with them, another old thread:

Printed circuit pins repair

Generally:

If you use the original connector, inspect and solder/ repair the pins, as they are crimped to the board and can lose electrical connection

Instrument regulator/ limiter.......replace with a solid state one like RTE and solder jumpers across from the board traces to the connector fingers as shown in the thread above

Gauge studs lose connection. Consider replacing the "fake nuts" and loosen/ tighten them a few times to "scrub" the board traces clean

It would be wise to "jig up" the board and test the gauges for accuracy. You need test resistances for that:

View attachment 1715791159

If you have the fuel tank out, an extra sender, or an appropriate rheostat, you can set it with an ohmeter to the above resistances to test. The guage tester goes from the sender connection on the gauge to ground and you must feed the gauge power through a good gauge limiter/ regulator

Clean up and inspect the lamp sockets, buff clean the connection prongs on the sockets, bend as necessary, and clean the PC board, and replace bulbs. Some guys use LEDS but there are many brands and some do not play well with the dash dimmer control Also most LEDs are polarity sensitive. You will not blow them up, they just won't light if reversed
Thanks so much!
 
Welcome! Nice lookin project!
 
Thanks so much!

I didnt use the painless set up , (E Z) , but had to take the orig. individual connectors out of the chevy connector on the new kit and install them in the orig. mopar connector. , w/ a very thin small screwdriver , and match them to ur steering column plug , getting the right order is the hardest part - did u get a cross reference for a chevy to mopar schematic ?
 
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