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My harness was made for the 138CD. The only difference from the 120 is the added length for the brake and tail light wires. Everything else is the same. The cigar lighters, dome lights, speedometer light, instrument light, map light, clock, clock light, heater, and defroster were all wired with point-to-point wire and not part of the main harness.

I have somewhat isolated the tail light dimming problem. The issue is clearly internal to the main light switch.

The way I tested is this:

1. Verified that I could again repeat the issue as before. I did observe that the tail lights dimmed more in the “instrument light” position than it did with the “map light” position. But, very repeatable…check.
2. I connected a jumper around the main light switch to the tail light and dash light circuit. With this, the tail lights were bright and did not dim with the map/instrument lights. This confirmed that the issue was not a ground problem and clearly indicated that the issue was with the main light switch. It also makes sense that the “map light” position did not cause as much dimming since there was only one bulb instead of three (gauges, clock, speedomter).

Now…my headlights, parking lights, dome lights, tail lights, and brake lights are all LEDs. However, the clock light, gauge light, speedometer light and map light were still the incancdescents. That made me curious given the previous issue I had with everything being incandescent and the thermostatic relay cutting in and out.

So, I replaced the remaining incandescent bulbs with LEDs….guess what….the tail lights never dim.

Now, in replacing the bulbs, you have to pull out the sockets which is the ground connection. So I was inherently touching the ground in this process. Due to that, I then reinstalled the incandescent bulbs and verified that the tail light dimming did, in fact, resurface. I then reinstalled the LEDs and the problem again disappeared.

During this process, I also noticed another issue that would also indicate a problem with the main light switch. In the Parking Light position, all is good. In the Country/Passing position, all is good. However, in the City position, all lights, headlights, tail lights, dash lights, have a slow flicker.

Anyway, clearly the issue is with the main light switch….it could be dirty contacts, but I know there is an issue with the thermostatic relay as well. Given everything I’m doing, I will get the main light switch taken care of.

On another note to revisit a topic of old…..As you may recall, I had a persistent issue with my old Stromberg EE14 carburetor with fueling bubbling out around a shaft after the car was shut off. Now, that I replaced that carburetor with the Carter WD-0 (which has been a dramatic improvement), I was able to do some looking at the Stromberg. One thing that I noticed very clearly is that it needs to be rebushed. That shaft was quite loose and sloppy.

Next topic….I ordered the wire I will need to re-wire the items that are not part of the main wiring harness….cigar lighters, dome lights, clock, etc..

Next up…replace the missing rubber to my inner fenders so that they will be ready to go back on the car. I haven’t bothered putting them back on since I’ve been doing other work and they get in the way. Fortunately, I made a little bit of an index of BigKev’s blog a while back so I could quickly find topics that I new I’d get to eventually…..inner fender rubber is page 41 of BigKev’s blog according to my notes.

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Did you order a full harness for the car, and it didn't have all the circuits, or did you order a partial harness? I haven't ordered a harness recently, but I would have thought that it would have all the wire needed for the car. At the risk of going off-topic, are all wiring harnesses like that?

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Check out this list of all the harnesses used in V8 cars. This list does not even include Torsion-Level or Overdrive harnesses...

packardinfo.com/xoops/html/modules/newbb ... 9057&post_id=280080#forumpost280080

It is a full harness. Keep in mind that the cigar lighters were options as was the heater and defroster. Then, on my car, it adds a second cigar lighters and a second dome light with three-way switches.

If have to think about just how complicated the harness would be come if you have a wire from the harness to the dome light switch and then a wire from the dome light switch back into the harness that now has to snake up through the frame to the center divider. It would have been quite complicated.

My harness matched exactly the original harness that came out of the car (I still have it). I also still have all the old point-to-point wires that were removed.

Don, I guess it's just a difference in terminology. Understand that more modern cars have a whole bunch of sub-harnesses, but if I ordered a harness for a car, I would expect all the wiring to be included in the harness, even the point to point wires. Oh well. Not a big deal, I'm just surprised.

Yeah, I get it. I think there are just a lot of unknowns associated with it. Part of the issue with the point-to-point wires is that many of the options were installed by dealers. They may not have always installed the heater and defroster switches in the same location etc…

In fact the 120 wiring diagrams don’t even show the heater/defroster, clock, cigar lighter, or dome lights. The heater/defroster, clock, and cigar lighter, I understand as those were options. But it surprises me that the dome light(s) aren’t shown on the wiring diagram.

It’s just how they did it.

A while back, I created my own version of the wiring for my car based on Packard’s diagrams. I cleaned them up a bit yesterday. The real benefit is for the main light switch as my diagrams provide a functional view of the different switch positions.

In these diagrams, everything in blue is part of the wiring harness. Items in red are non-original items I have added for my car…electric fuel pump (as a backup) and a couple of fuses. Items in green are original items where the wiring is not part of the wiring harness. For the items in green, the wire gauge I’m using may not match up to original…Packard use 18 gauge in a few places and I decided to keep things simple on my car. Also, all of the wire shown in green was just black wire. I have added a couple of tracers for my own benefit.

One item in green that is a little different is the clock and associated clock lamp. Those were not part of the main wire harness, but the clock (if purchased) came with a small “harness” to wire it up.

Also, I did make a change…The cigar lighter(s) and clock would have been tied in after the original fuse (in blue). I decide to separate the cigar lighters from everything else with their own fuse.

Lastly, as you can see, I added a fuse for the heater/defroster circuits. This was a separate point-to-point wire originally without the fuse.

Hopefully, others will find these useful as well.

I've never liked how Packard did some of their wiring. I believe everything should be independently fused wherever possible. But, this is all "Monday Morning Quarterbacking" based on modern expectations vs what was "industry norms" back then.

The instrument/map light switch is also something else I've always found goofy. Scenario: if you're driving at night, and the passenger needs to turn on the map light to read something, you lose all your gauge lights. And why wouldn't you want the dash lights on by default when the headlights are on? Eventually, Packard phased all that out.

As you know, I directly wired my dash lights to come on with headlights. The map light works as usual, and the what was the instrument light position on that switch now turns my backup light on or off.

I am not using the fuse on the light switch as my aftermarket harness has its own fusebox, and everything is independently fused.

Also, I didn't care about the whole country/city headlight modes. So I wired it like the later cars. I bridged the 3rd and 4th positions on the switch together so that either position turns the headlights on, and the dimmer controls the hi/lo beams on both lights.