78 w100 - Ignition switch wires tied to new harness
 

I have a new wire harness through Painless, and I’m having difficulty finding information about my stock ignition switch wiring I’m tying it into.

the most accurate intel I can find shows that I have
starter, ground, ignition, batt 1, batt 2, acc 1, acc2 wires…

my question is how to tie into new harness that only has batt 1 and acc 1?

I’m assuming that the acc 1 is non engine accessories, and acc 2 is power to engine running accessories ( the new harness has a “ignition switches fuse panel” and “accessory fuse panel”), so be I think I know how to wire that.

The 2 batt wires are what are even more so tripping me up. Any explanation is welcomed. Do I wire different or tie the two into one?

I have 1977 trucks so I'm betting the wiring didn't change that much but, I don't like to assume anything.

Is this a universal harness or direct fit? (their website doesn't seem to list anything for Dodges)

Could you link to the harness your using? I believe the best way to solve this is to look at the install manual for the harness and a wiring diagram for your vehicle. Also a multimeter and test light wouldn't hurt either.


Are you retaining the stock electronic ignition? I ask because it requires two wires off the key like a breaker point system to bypass the ballast during cranking.

Are you retaining the stock alternator? I ask because it has wiring for an external voltage regulator.

Ill have to find the exact harness online (bought it over a year ago), but it’s a universal harness with mopar wiring colors essentially.

I am using a ballast and the voltage regulator for the alternator, but I don’t believe I’m using the stock electronic ignition.

The install manual was very thorough with everything in the engine bay, but they’re vague about any wiring under the dash. The directions basically said connect the wires with their corresponding colored wires (but they’re listed incorrectly [after I finally found a wire diagram that corresponds with my existing wiring]).

I’ll find some pictures and a link of the wire harness but it’s primarily figuring out what the stock ignition switch wires actually do. The diagram I have doesn’t give me the details I need (or I just can’t read it).
https://cimg4.ibsrv.net/gimg/moparfo...f8b61c601.jpeg
The only diagram I could find with accurate ignition switch wiring colors.

This is the closest harness to what I have; I think this one is just slightly updated.

https://painlessperformance.com/prod...part-no-10127/

It looks like the first Accessory starts out as a Black wire (ACC 1-14BK) and then on the truck side of the connector harness transitions over to a Light Blue wire (Q1-14LB). It powers three fuses which are (20A) “HORN B/UP”, (20A) “IGN ACC” and (5A) “RADIO”. I highlighted this brown in the attached image. It also powers the wiper motor which is why it slips off before going to the fuse box but, this isn’t shown in my screen shot.

And it looks like the second Accessory starts out as a Black with Red tracer wire (ACC 2-12BK/RE) and then on the truck side of the connector harness transitions over to a Light Blue with Red tracer wire (Q2-12LB/BK). It powers only one fuse which is (20A) “HTR AC”. I highlighted this red in the the attached image.

BATT1 and BATT2 are already connected to a junction in the wiring harness so I wouldn’t think joining them would change anything. I highlighted them blue and green in the attached image.

As for if the ACC1 And ACC2 of the switch can be joined together , I would want to do more testing of the switch itself before making that call.

For example...
If ACC1 and ACC2 behave exactly the same way when operating the key I can’t see why it would matter if your joined them…
However, I’m willing to bet ACC2 acts different in one regard to ACC1 in that it probably isn’t powered ON when the key is in the Accessory position because you wouldn’t want your HVAC (blower, A/C Clutch, etc) to be energized while your parked listening to the radio.
You may even find BATT2 isn’t necessary if for example it’s only used for ACC2 and you end up not using ACC2.

But, this is just a guess, you’ll need to use an ohmeter to confirm and take notes of the switches operation.
Lastly, after looking at the install manual since this is a Mopar targeted harness it looks like it has
sections that address little detail like the charging or ignition system.

However, here are a few more tips. If your using an aftermarket ignition system, these usually only use one (HOT) wire to power them. You need to make sure the ignition gets uninterrupted power when the key is both in the Cranking and Run positions. It’s possible the painless harness already accounted for this but, if not you’ll need to join two wires together.



One last thing if your truck still has it’s original ignition switch and it’s having issues I wouldn’t replace it with an aftermarket, I’ve found their not built very well, try to get a New Old Stock instead.


https://cimg9.ibsrv.net/gimg/moparfo...1699e32f1c.png

thank you so much! I appreciate it. I’ll keep you posted as I test and figure things out.