GMachinz wiring harness help, please?
 

I got a wiring harness from GMachinz about a year ago and I’ve only now got round to cleaning up the old wiring and installing the new harness. I’ve cleaned up the cab and installed the new harness from gmachinz but there’s a few plugs with nothing to connect to? I can’t work out what these should collect to??

Also there’s a port on the base of the steering column with nothing connected to it and I can’t work out what should be in there. Any ideas?

There’s also a separate wire coming out of the firewall and I don’t know what it is.

Sorry for the dumb questions but this has been a pain in the ass truck. There’s something new wrong everyday.

Re: GMachinz wiring harness help, please?
 

White switch is Neutral Safety Switch(NSS). Purple wire should connect to the NSS. Guessing the NSS is bad which would explain the jumper on the purple wire connector. IIRC - purple wire goes to starter. I think the pair of green wires go to the NSS as well.

The last 6 pack connector look like what goes to the Dual gas tank switch.

Re: GMachinz wiring harness help, please?
 

Light green & dark green pair = backup and go to safety switch .
Purple is park & neutral safety to starter .
Single orange possible th400 gas pedal switch for passing gear kick down .
The multi wire plug is power window I think . It don't look like my fuel tank switch plug .

Re: GMachinz wiring harness help, please?
 

Thanks I don’t have power windows so it’s the gas tank.

What’s confusing the crap out of me is there was nothing connected to the “NSS” when I took out the old wiring harness.

Re: GMachinz wiring harness help, please?
 

my 87 gas tank switch plug has the terminals square not angled .

Re: GMachinz wiring harness help, please?
 

81-91 are a different system from the 73-80 setups.
That plug looks like the 73-80 NL2 dual tank switch plug.

Re: GMachinz wiring harness help, please?
 

So I got most of it hooked up and everything mostly works. My headlights don’t work but high beams do!

But there’s a few wires where I still don’t know what to do or where they go:

There’s a connector on a long single black and white wire (in a loom) and I have no idea where this goes.

Out the back of the heater selector there’s a connector that I don’t what it connects to and on the other side there’s a black and orange connector that I connected to a brown wire out of the main harness (I’m now thinking I should connect these two brown wires together (that winks then leave the black/orange wire with nothing to connect to)

There’s a little red/white/black wire with a connector out of the wire for the fuel selector switch. I don’t know what this should connect to?

Finally on the fuse panel there’s a few connectors just hanging there, these were not on the original (the original had just random wires spliced in all over the place).

Any help is really appreciated, I’m so close to finishing this up.

Thanks

Re: GMachinz wiring harness help, please?
 

The short "pig-tail" wire that comes from the heater blower switch is the power supply for the heater blower. That needs an ignition-hot source.

Was this harness supposed to be an exact duplicate of a factory harness? I'd have thought Gmachinz would have the courtesy of providing an accurate diagram of the harness.

Re: GMachinz wiring harness help, please?
 

Yes it’s supposed to be an exact replica. There’s was no documentation or diagrams included.

The old wiring harness was all messed up and I was advised this was my best option to clean it up. It’s neater now but there’s still some stuff I have no idea where it goes.

Re: GMachinz wiring harness help, please?
 

Look for a year-correct wiring diagram among Hatzie's collection(see his signature). Identify what you can using wire color and approximate size. Then confirm your ID by checking ohms between both ends of the wire.

For example, you'd look for a wire that matches one of those unknown pigtails. When you have a likely suspect, you check for continuity between that pigtail and the supposed other end of the wire. If you have continuity, you've successfully identified that wire.

A last ditch effort that is still surprisingly effective, is connect an ohm-meter to that unknown pigtail, and then while all other connectors are disconnected, just start probing all of them at random. You will get a hit at some point, confirming both ends of a circuit. When dealing with the fuse box, you'd want to do this with the fuses out, since they can really confuse things.

Re: GMachinz wiring harness help, please?
 

long black with white tracer and single plug should be seat belt warning buzzer switch driver seatbelt latch on floor .

brown short single off heater switch should have a female plug half in the main harness it just reaches . the main harness will be held up to the tabs on the bottom of the dash frame .

Re: GMachinz wiring harness help, please?
 

Ok. I don’t have anything to connect the swat belt buzzer too. This truck has been so messed with over the years that it’s probably long gone.