I turn the key, and I can a click sound in the dash and voltage regulator. I have a new battery, and the starter operates when jumping the starter solenoid. I should mention, that the backup lights do not appear to work. I have installed new bulbs. Bulbs to not appear to light even when rowing through the gear selector.
What order of steps are recommended to narrow this down?
You didn’t say exactly how you jumped the solenoid. Did you put power to the S post and then it cranked, or did you jump from the battery post directly top the starter post?
Sorry, power to the S post.
It sounds like the reverse light switch / starter crank switch has come unplugged. They go through the same underhood 4 prong connector.
Is that the same as NSS? If so, it is connected.
It is the neutral Safety Switch. If it’s not adjusted properly or failed you will have the symptoms you describe.
Is there a way to test if the Neutral Safety Switch is good or bad? I believe the shop manual will tell me how to adjust it.
You might try to wiggleing the shifter handle while turning the key to start the engine. If it is the switch you will most likley engage the starter.
If wiggling the shifter handle, would allow it to start, shouldn’t I be able to see backup lights?
Sure just use a volt meter to test it. The contacts for the backup lights are separate but in the same switch and can fail separately of course. More typical is the wrong bulbs in the backup lamps or rusty sockets / broken wires. Most auto part stores don’t carry the correct bulbs.
Today I used a multi-meter to test the NSS. I have continuity, but not in the park/neutral, so I believe an adjustment is necessary. No continuity in backup circuit as of yet. I did find random wires w/female ends that may or may not need a partner. Do these need a dance partner?
white with red stripe just kinda hanging near the brake pedal arm
That single wire with red plug is your PRNDL lamp wire source.
That’s strange, because as we moved the selector through its range, each of those positions lit up. 
The neutral safety switch for a C4 and C6 transmission is on the transmission.
Your PRNDL light, which is in your shifter bucket, is working properly.
The baby blue wire with the red stripe is instrument backlighting. The wire pictured supplies voltage to the console clock backlighting bulbs in an XR-7 console.
Alright, baby blue wire goes to my Xr7 clock backlighting. One down one to go. Any idea on the white w/red stripe?
white/red is your oil pressure signal line.
Appreciate all the help.
Still having issues. I believe the NSS is giving me fits. I pulled it off the trans, and bench tested it to find continuity in park/neutral, which I found. I plugged it into the harness without mounting it to the trans, turned the ignition key, and the engine turned over. Was unable to get continuity in reverse. Ordered new NSS.
Today installed new NSS but did not tighten, made some linkage adjustments, tried reverse, reverse lights worked. Tried the key, engine does not turn over. Messed around with linkage and NSS. I have continuity in Park, Neutral, and reverse. I have no Reverse lights, and no crank. Gotta be something I am missing, something simple.
What should be my next step?
The starting system relies on 7 major components
Powering up the ignition switch:
Power from the battery is supplied Starter Solenoid’s Battery terminal. Attached to this terminal is circuit 37 (Black Yellow) that runs to the firewall’s flat 4 prong connector. Circuit 37 then continues into the passenger compartment where a main splice in the harness feeds multiple sources which includes the following:
clock (circuit #22 Blue Black)
brake light switch (circuit #10 Green Red),
headlight switch (circuit #25 Black Orange) and
ignition switch (circuit #21 Yellow)
The ignition switch circuit attaches to the switch’s B post. When the ignition switch is turned to the Start position, The B and S posts connect providing power to circuit #32 Red Blue.
When the ignition switch is turned to the Start position, power from the ignition switch goes to a 4 wire square plug located under the dash near the steering column. If the car has an automatic transmission, the wires go to the neutral safety switch located on the transmission case. Note the neutral safety switch connects the circuit only when the transmission is in the Park or Neutral position.
Cars equipped with tilt away steering then route through to a starter safety switch located on the steering column near the vacuum motor so the car cannot be started in the tilt away position. See http://www.concoursmustang.com/speegle/67%20Mustang/Article-67Tilt.pdf
Power then goes back to the square firewall plug on to the starter solenoid’s S wire Circuit #32 (Red-Blue) wire. This in turn engages the starter solenoid’s internal coil and closes the solenoid’s plunger to provide 12 volts to the Starter (via the cable from the starter solenoid’s post opposite the battery connection to the starter) and the I wire circuit #262 (brown) wire. At this point the circuits are complete so that the starter motor should engage and crank the engine.
However for the engine to fire, the i wire Circuit 262 then goes back to the firewall where it connects to the ignition circuit’s #16 (red-green) which goes to the coil, providing power when starting. (Note: the power draw by the starter motor consumes 100+ amps and thus power provided to the I circuit will measure roughly 9 volts, not 12 volts. This is why the resistance wire is bypassed during starting and not to give a brief 12 volt jolt to the ignition systems when starting!!!)
Once the car fires and you return the ignition switch to the Run position, the S circuit disengages (the starter stops cranking) now the ignition switch disconnects the B and S circuit but powers the B and I circuit.
Note the connector at the firewall also connects circuit #16 (to the coil) and the ignition switch on circuit #16A (the pink resistance wire). When the car starts and you return the ignition switch to the “Run” position, power to the coil is now provided via the ignition switch on circuit #16A at a reduced voltage of 8 to 9 volts. If you have an XR7, the power from the resistance wire goes to the Tachometer then to the firewall. If you do not have power at the coil in run position with an XR7, place a bypass wire across the tachometer and retest for power at the coil. Note if the car is running, and you put a Voltmeter on the Starter solenoids I post, you will also read 8 to 9 volts because the wires are all connected at the firewall thus back feeding power from the resistance wire.
I hope this clears things up.
Coach Jack
