Wire Harness Questions

[72GY9Runner]

So....
I'm in the middle of re-assembly of my 72 Runner, and I've run into a small problem in the engine compartment area. I'm sure all wiring was there when I took the car apart, but I seem to have misplaced a small section of wire harness. I'm hoping some of you can tell me what this harness runs too as it may help me in finding it in my boxes of parts.

On the main firewall connector, I have both main harnesses with the wide connectors, and the small connector that goes to the wiper motor assembly. I seem to be missing the other small harness.

What does this connect too? (I think it may be washer bottle, and part of the neutral/backup circuit but I can't remember). If I don't find the harness I plan on building a new one using a donor E-body harness, but I'll need to know the wiring pin-out.

In case it makes a difference, this is a 400ci, Auto, with A/C

If anyone has any pics/ diagrams I'd appreciate hearing from ya.

Thanks,

Dave

[Moparlar]

Possibly the neutral saftey switch harness.

Larry

[71_DEPUTY]

correct- black and blcak wire with a white tracer wire to the netural switch on the tranny- for a manual

auto- add 1 wire- brown with a yellow tracer wire to the starter relay- ground for the relay.

John Mac

[72RoadRunnerGTX]

Here's the diagram.

[72GY9Runner]

Thanks lots guys, you're AWESOME!

Oh... I see the #4 pin on that connector has something to do with A/C. Do you by chance have the A/C inset diagram or just what it connects to?

Dave

[72Rdrnner]

Thanks lots guys, you're AWESOME!

Oh... I see the #4 pin on that connector has something to do with A/C. Do you by chance have the A/C inset diagram or just what it connects to?

Dave

Pin #4 connects to the air conditioning motor. (heater fan motor) (C5-14DGN) This wire goes to the three pin plug that attaches to the blower motor switch on the dash a/c controls. It goes to pin #3 on that plug.

Pin #20 connects to the system low pressure sensing switch on top of the dryer. The other connector on that switch goes to the air compressor clutch. (C2-18DBL)

I haven't gotten my FSM CD (it’s in the mail from eBay) yet so can't post a copy of that particular wiring diagram. It's found on the top page 8-154 in the small block labeled "Air Conditioning". You kind of need this to trace that pin #4 wire. The pin #20 wire is really straight forward.

There is also a detailed diagram of the "Air conditoner control wiring" on pg 8-163 that shows exactly where the #4 and #20 cavity/pin wires go. This is really the best one if someone who has a FSM on a CD can post it.

I can try and scan it but I won't be able to do that until tomorrow.

[72RoadRunnerGTX]

A/C insert

[72GY9Runner]

I'll say it agian... AWESOME!

I did some tracing last night, and found most of the missing harness, but also found this;

#1 The 3 wire neutral switch plug has been hacked up and spliced only to the single solenoid wire. Not sure how backup lights will even work like this?
#2 The low pressure and clutch system for the AC has also had the wire harness "custom built" and looks like it was just spade connectored into the bulk plug.
#3 There are 2 wires on the heater motor (green and black). The green wire was undamaged, and I connected it to the harness no problem. The black wire has been cut, and has had (at some point) another wire twisted onto it but it is now missing. I assume this is where wire #4 from the harness goes.
#4 All the under dash harness to the bulk connector is ok and in place with the exception of a cut and crimp connected hot wire for the ignition switch. This is a "fix" I've seen before on mopars.(I'll properly solder and heat shrink this)

#5 - Conclusion, whoever owned this car back when this re-wiring happened... was a butcher.

The original bulk connector for the missing harness is melted slightly, and the wires were just cut off and twisted togeter. I suspect an underhood fire or wiring malfunction of some kind at some point in it's life.

So, with the help of your diagrams, I'm going to make up a new harness from some e-body spares that I have laying around.

Just when you think the hard work is over, you find a whole mess of new broken stuff to deal with. You'd think I'd have learned this by now. Lol

Thanks again,

Dave

[72RoadRunnerGTX]

This Pic shows the black wire from the blower motor grounded to one of the wiper motor studs. The dark blue wire from the A/C low pressure switch, although wrapped together with backup light/neutral safety switch wires, located at what appears to be position 20 of the bulkhead connector.

[72Rdrnner]

I scanned FSM page 8-163 and cropped it. This shows where the #4 and #20 wires go. These two pins are kind of oddballs as they apply only to cars with airconditoning. I assume they are empty on non a/c cars.

If this image doesn't come out that well my FSM CD is in the mail and I'll get a better pix when it gets here.

NOTE: I tried to post via attachment a better image but I get the 500KB limit message which is odd as I can't find any images I've attached. So this one comes from Sony Image Station and unfortuately is smaller.

[72Rdrnner]

I did some tracing last night, and found most of the missing harness, but also found this;

#1 The 3 wire neutral switch plug has been hacked up and spliced only to the single solenoid wire. Not sure how backup lights will even work like this?

If only one of the wires is connected this will be a problem as that switch does two things. Turns on the back up lights when reverse is selected and completes the starting circuit when in park or neutral. If only one wire is hooked up something isn't going to work.

#2 The low pressure and clutch system for the AC has also had the wire harness "custom built" and looks like it was just spade connectored into the bulk plug.

That sounds OK. That wire is separate from just about everything else as it is only there on a/c cars.

#3 There are 2 wires on the heater motor (green and black). The green wire was undamaged, and I connected it to the harness no problem. The black wire has been cut, and has had (at some point) another wire twisted onto it but it is now missing. I assume this is where wire #4 from the harness goes.

I'll have to go out to my Roadrunner and see exactly where the wire from the #4 cavity/pin goes. Both the #4 and #20 wires on my car are originals as I seem to remember I could NOT find a replacement a/c wiring harness. I did find and replace all the others.

#4 All the under dash harness to the bulk connector is ok and in place with the exception of a cut and crimp connected hot wire for the ignition switch. This is a "fix" I've seen before on mopars.(I'll properly solder and heat shrink this)

Sounds like a good plan. I took the entire block from the inside of the firewall off so I could replace the gasket that goes around it where it goes through the firewall. The old one was pretty much dried out. I got some of that nifty grey gasket material like is used on the tail light lenses and cut a new one. It takes a little time as it has all sorts of curves and cutouts, plus it's not very wide (1/4 " max)

#5 - Conclusion, whoever owned this car back when this re-wiring happened... was a butcher.

Fortunately for me no one else ever owned my car but me so didn't have that problem.

The original bulk connector for the missing harness is melted slightly, and the wires were just cut off and twisted togeter. I suspect an underhood fire or wiring malfunction of some kind at some point in it's life.

I have found all four of the engine side wiring harness plugs in junk yards and took some of. You can basically tear them completely apart and rebuild them. The male spade lugs can be pulled out from the backside of the plug by squeezing them together with a real small pair of needle nose pliers. There is a foam gasket in the plastic plug that has a slot where each spade goes that you can make new as it's pretty simple.

The best thing is to get some of that Zep Orange (Home Depot has it) and soak the entire harness to include the plastic firewall plug for as much time as you have (the more the better). It will clean all the grease off and actually soften up the insulation. From time to time take it out of the soak, wash it of with hot water, then put it back in for some more soaking.

I did this with my old harnesses for a month or so just so I could have them for parts (like one of the fender light plugs that was defective on my new harness) I also use the Zep Orange to soak bits and pieces of wiring harnesses I get at the local junk yard. One cannot have too much extra wiring stuff!

So, with the help of your diagrams, I'm going to make up a new harness from some e-body spares that I have laying around.

As I said check out the local junkyard. I found a 1973 Dodge pickup that had a complete and in good shape firewall connector. I took it out, pulled all the wires out and presto had a new set! Just in case one of those tabs that hold them in place breaks off! Or I restore another Roadrunner!

Just when you think the hard work is over, you find a whole mess of new broken stuff to deal with. You'd think I'd have learned this by now. Lol

Just like Forest Gump and that box of cherries! Always finding something new & interesting!

Thanks again,

Dave

[72GY9Runner]

Thanks for both the diagrams, and the firewall picture. Both were a big help!
I've basically got the car wired up now except for the neutral/backup piece, but that wont be difficult. I went and checked out all the wrecks out on my dad's acreage on the weekend, but unfortuneately nothing had the correct style of firewall connectors(my e-body harness was missing the same section). Looks like it's time for a trip to the auto wreckers.

BTW: Cool cleaning tip for the wire harness. I'll try that. I usually clean my seat belts, small wiring peices, and any small pieces that aren't grease covered with a run through the dishwasher. The dish detergent does an awesome job of cleaning things, but it doesn't make my wife very happy.

Dave