1970 Newport wiring screwed up

[Newport_70]

My new "challenge" is to fix the wiring of a 70' Newport which has been screwed up by "experts" years ago. She doesn't run since then.
Had a first look under hood and dash which was kinda bad surprise. Quite some wires simply cut, sticking out the harness, some wires added all over the place, no name electronic ignition, electronic alt regulator wired in using AWG 18... and so on. This will need some time but she's worth it to spend the effort.
I did fix quite some old cars' wiring and made new harnesses from scratch, so I have some background, but ZERO on Mopars.
What I usually do as the baseline is to understand the wiring scheme. Many cars / brands have specific "things", be it typical failures or weak points.

So my first question for you guys is, what is the correct wiring diagram for the 1970 Newport ?

On MyMopar I did find an archive with 70s wiring diagrams, however there is no specific for a 70' Newport. The closest might be "Chrysler A" or "Chrysler B", but I am hesitating to start w/o being sure to work on the correct one. I am used to the fact some european cars have different wiring schemes, sometimes significantly changed three times a year - for the very same car. So that is why I am hesitating...
I have the Electrical assembly manual already (which doesn't help a lot at first) and I don't mind if I have to pay for the correct wiring diagram btw.

Txs for any advice

 

[luigi164]

Download from My Mopar the FSM. ( '70) There are electrical overvieuws in it.

 

[Newport_70]

Thank you very much !
Got the diagrams printed already, 12 x 17 , for my old eyes

 

[CBODY67]

While you're doing this, would be a great time to include the "Ammeter Bypass" upgrade in the mix, too. Several good threads in here on how to do that simple procedure.

Keep us posted on your progress,
CBODY67

 

[Newport_70]

For sure I'll do this.
Did read through some posts already the only bigger effort seems to remove the entire dash/console.

If there are any other must do's, or strongly recommended ones, please let me know

Will keep you posted

 

[CBODY67]

At the assy plant, the instrument panel was put together "off-line" and then installed in the vehicle as "a unit". Before the front seat was installed.

When we restored a SuperBird, the car was plastic media blasted and then put back together. The instrument panel was laying on a bench. It was assembled like that, so there was access to all of it from the back and front. When it came to be time, the hvac items were re-sealed, etc. Then the instrument panel assy was "walked through" the front doors, the bolts holding the structure to the body shell we installed loosely, then later tightened down, the vac and electrical harnesses were hooked up, the steering wheel installed, etc. until all was done. Otherwise, massive amounts of uncomfortable time laying "over the hump" in the floor. If doing all of that work, might as well be comfortable while it's being done. A different way to do things.

Something to consider,
CBODY67

 

[Big_John]

I've had the dash out of my '70 300. Unbolting it is easy, disconnecting and then reconnecting the wiring can be challenging.

Remove the steering wheel and unbolt the column so it drops down. Remove all the A/C ducts and disconnect any wires you can reach from the bottom first. The easiest way is to loosen the bottom bolts and then remove the speaker grille and unbolt the top. Then you can swing it towards you and disconnect the wiring behind the dash. Once done, a guy on each end removes the bottom bolts and carry it out of the car. Put it back the same way. In the back of the electrical section of your FSM, there's all the plugs shown behind the dash.

Never mind the messy table... I had this inside when it was cold out in the garage. Note the stands, they were made from some scrap bed frame. I strongly suggest you make something like this, even plywood/ 2x4 stand because you will want to have it standing up in front of you when you work on it.

If you want to repair the harness, grab a piece of plywood and with some finishing nails, lay out the pattern of the harness. From there you can strip the tape and start replacing wires one by one. This is the way the pros do it... and I've been in shops making wiring harnesses for high end sonar and they build them just like this... A piece of plywood with finishing nails.

An excellent place to find correct wire and most of the terminals is Rhode Island Wiring Service Inc.. Their website isn't the easiest, but it gets you there. You want to use black electrical tape that has no adhesive to wrap it back up when done. That can be hard to find... Here's what you want, you may find it cheaper somewhere else. Qty1 Electrical PVC Wire Wiring Harness Tape Non Adhesive Black 3/4" x 88yrd | eBay

 

[3175375]

I've had the dash out of my '70 300. Unbolting it is easy, disconnecting and then reconnecting the wiring can be challenging.

Remove the steering wheel and unbolt the column so it drops down. Remove all the A/C ducts and disconnect any wires you can reach from the bottom first. The easiest way is to loosen the bottom bolts and then remove the speaker grille and unbolt the top. Then you can swing it towards you and disconnect the wiring behind the dash. Once done, a guy on each end removes the bottom bolts and carry it out of the car. Put it back the same way. In the back of the electrical section of your FSM, there's all the plugs shown behind the dash.

View attachment 624222

Never mind the messy table... I had this inside when it was cold out in the garage. Note the stands, they were made from some scrap bed frame. I strongly suggest you make something like this, even plywood/ 2x4 stand because you will want to have it standing up in front of you when you work on it.

View attachment 624223

If you want to repair the harness, grab a piece of plywood and with some finishing nails, lay out the pattern of the harness. From there you can strip the tape and start replacing wires one by one. This is the way the pros do it... and I've been in shops making wiring harnesses for high end sonar and they build them just like this... A piece of plywood with finishing nails.

View attachment 624224

An excellent place to find correct wire and most of the terminals is Rhode Island Wiring Service Inc.. Their website isn't the easiest, but it gets you there. You want to use black electrical tape that has no adhesive to wrap it back up when done. That can be hard to find... Here's what you want, you may find it cheaper somewhere else. Qty1 Electrical PVC Wire Wiring Harness Tape Non Adhesive Black 3/4" x 88yrd | eBay

We had a setup like you describe for the F-14 radar system harness routing that was ‘pegged’ out to reflect the lengths of the harnesses in the aircraft.
This setup was to fabricate a system harness as a lab setup. We did this for several systems (F-15, F-18, B-2, Global Hawk (RQ-4), etc, etc)

 

[Big_John]

We had a setup like you describe for the F-14 radar system harness routing that was ‘pegged’ out to reflect the lengths of the harnesses in the aircraft.
This setup was to fabricate a system harness as a lab setup. We did this for several systems (F-15, F-18, B-2, Global Hawk (RQ-4), etc, etc)

When my ex-wife worked for GE building towed sonar arrays for subs, they used a set-up like that too. I think that was the first place I saw it. That was almost 40 years ago. I was back in there some years later, GE had sold to Lockheed Martin and they were still using the same method to make harnesses. I saw them at a lot of other places too.

 

[Newport_70]

quick update.
Got into it today...traced it down.
Put it some workarounds/bypasses, now she's running, alternator and regulator working.
Next is to replace the temporary fixes by final ones.
Aside minor issues a key problem are the four firewall bulkhead connectors, they are pretty much corroded.
As the bulkhead cases don't look too bad, not melted, I thought about buying new terminals to re pin male and females.
As far as I figured out, these guys should be the correct terminals.
Correct?

I think I have the right crimping tool, will buy surplus and to some testing.

 

[Newport_70]

oh btw..the technique to build harnesses, the "nail board", is what I learned during my apprenticeship. It also was all military stuff, high temperature wires and... white color only. Still remember the "fun" we had during troubleshooting. So Mopar is much easier

 

[Big_John]

quick update.
Got into it today...traced it down.
Put it some workarounds/bypasses, now she's running, alternator and regulator working.
Next is to replace the temporary fixes by final ones.
Aside minor issues a key problem are the four firewall bulkhead connectors, they are pretty much corroded.
As the bulkhead cases don't look too bad, not melted, I thought about buying new terminals to re pin male and females.
As far as I figured out, these guys should be the correct terminals.
Correct?

View attachment 625143

I think I have the right crimping tool, will buy surplus and to some testing.

Yes, Packard 56 are the correct ones to use.

 

[3175375]

oh btw..the technique to build harnesses, the "nail board", is what I learned during my apprenticeship. It also was all military stuff, high temperature wires and... white color only. Still remember the "fun" we had during troubleshooting. So Mopar is much easier

We added orange instrumentation wiring that also was stamped with the wire numbers on them.