Topic: 65 engine gauge feed 289 Harness

[ChrisV289]

So I am looking at my wires and I'm concerned about the wires at the starter solenoid as you can see in the first picture. I ordered a new harness from NPD as Midlife's website suggests not restoring this feed. The connection for the oil pressure wire looks different. I can't see the join on my original harness. On the new one it is a two piece system. Is that suppose to be like that and is it supposed to be hidden? Also awhile ago I bought a separate oil pressure wire to replace my original as the covering was deteriorating but again couldn't find the connecting point. The end on that one is a bit different. Thoughts on that oil pressure wire or can the old harness be saved or no?

[midlife]

I may have an answer:  The spade/spade version is for the indicator lamp version; the bullet/spade combination is for the gauge version.  I hope that is correct...

1965 had two versions, depending upon whether it was the standard (swept speedometer) or 5 gauge cluster (GT/Pony Car interior).  And the standard had two different versions, depending upon the inliner or the V8 engine.  Another reason why I try to avoid selling these from my stockpile...I can't determine what is for which engine.  *sigh*

[CharlesTurner]

The gauge sending unit would have had a push on 90 degree end.

[ChrisV289]

So here is a picture of the harness stretched out. Could the middle wire perhaps be an extension that came with the harness? The other wire with the male end is the one purchased separately awhile ago.   

[midlife]

The gauge sending unit would have had a push on 90 degree end.

Duh!  You're right.

[CharlesTurner]

Did you have the original to compare the wire lengths?  I remember having to splice in a longer length for the oil sender.

[ChrisV289]

The original is still on the car.  Might try after Goodguys next weekend to remove it.

[ChrisV289]

So just laid the new wires along the route in the car and does not appear that I will need either extension for the oil pressure wire. Guess they throw an extra wire in there in case you need more slack.

[69cobrajetrugae2]

The 65 dealer equipped GT fastback isn't concourse like the real GT fastback sitting next to it collecting dust because we are too afraid to drive it.

Therefore the 65 dealer GT is on it's way to a new life as a Shelby GT-R clone and we will be driving it, oh yea!

In the process of sorting out the wiring the Fuse Box hot drop "Black yellow I think" and the Voltage Regulator Hot drop, "Yellow" are taped together and run along the core support. There was loose tape on said hot drops and it seems that there was a short at some point and the fuse link at the starter solenoid warped and buckled but did not break the circuit but the wires melted inside the tape.  The end result was a charging system problem since while both wires are hot, the voltage regulator hot drop is a dedicated circuit.

I attached a sub panel to the firewall nearest the starter solenoid and ran the three hot drops there each with it's own fuse, Alternator, voltage regulator, fuse box in power, and eliminated the fuse links after a bad fuse link brought the mustang into the fire zone.

The voltage regulator is internally grounded to the case and when I checked the ground drop resistance it was 6.9 ohms.  That resistance is the alternator idiot light bulb and the resistor wire pig tail 16b or 16a. When the key is on the idiot light glows because the voltage regulator under a no charge condition grounds the alternator idiot light circuit the power side of which is the resistor wire.  Since the resistor wire voltage feed is about 3 volts lower than the system voltage that is why the bulb will slowly glow when the idle speed is low and/or a charging system load exceeds the alternator output.

The resistor wire is a service item and voltage drop checks are a maintenance item to perform, check the Ford service manual. The resistor wire can fail either way, too much resistance or too little but I assume that the resistance will drop off with time which would cause points to burn prematurely and rather than replacing the resistor wire some owners opt for a petronics point switch which in my opinion, is a bad bad idea.

The ford yellow top is a wonderful 6 volt coil and as the engine RPM increases the resistor wire allows more current to flow to the coil and the points switching is fast enough to prevent the points from burning and the result is a hot precise secondary discharge which is not there in a petronics setup.

The resistor wire is 61 inches long and has pigtails, do not cut or splice it.  If anyone needs the factory resistor wire check procedure I have it in my 69 manuals, it must be the same as 5678 mustangs and I will post it.

If there is incorrect information with regard to the circuits please correct me and it will please me that someone is on the ball insofar as possessing a complete understanding of the early mustang electrical systems and the downside of solid circuit voltage regulators as opposed to the factory style points and coil units with thermistor controls.

[midlife]

The 65 dealer equipped GT fastback isn't concourse like the real GT fastback sitting next to it collecting dust because we are too afraid to drive it.

Therefore the 65 dealer GT is on it's way to a new life as a Shelby GT-R clone and we will be driving it, oh yea!

In the process of sorting out the wiring the Fuse Box hot drop "Black yellow I think" and the Voltage Regulator Hot drop, "Yellow" are taped together and run along the core support. There was loose tape on said hot drops and it seems that there was a short at some point and the fuse link at the starter solenoid warped and buckled but did not break the circuit but the wires melted inside the tape.  The end result was a charging system problem since while both wires are hot, the voltage regulator hot drop is a dedicated circuit.

I attached a sub panel to the firewall nearest the starter solenoid and ran the three hot drops there each with it's own fuse, Alternator, voltage regulator, fuse box in power, and eliminated the fuse links after a bad fuse link brought the mustang into the fire zone.

The voltage regulator is internally grounded to the case and when I checked the ground drop resistance it was 6.9 ohms.  That resistance is the alternator idiot light bulb and the resistor wire pig tail 16b or 16a. When the key is on the idiot light glows because the voltage regulator under a no charge condition grounds the alternator idiot light circuit the power side of which is the resistor wire.  Since the resistor wire voltage feed is about 3 volts lower than the system voltage that is why the bulb will slowly glow when the idle speed is low and/or a charging system load exceeds the alternator output.

The resistor wire is a service item and voltage drop checks are a maintenance item to perform, check the Ford service manual. The resistor wire can fail either way, too much resistance or too little but I assume that the resistance will drop off with time which would cause points to burn prematurely and rather than replacing the resistor wire some owners opt for a petronics point switch which in my opinion, is a bad bad idea.

The ford yellow top is a wonderful 6 volt coil and as the engine RPM increases the resistor wire allows more current to flow to the coil and the points switching is fast enough to prevent the points from burning and the result is a hot precise secondary discharge which is not there in a petronics setup.

The resistor wire is 61 inches long and has pigtails, do not cut or splice it.  If anyone needs the factory resistor wire check procedure I have it in my 69 manuals, it must be the same as 5678 mustangs and I will post it.

If there is incorrect information with regard to the circuits please correct me and it will please me that someone is on the ball insofar as possessing a complete understanding of the early mustang electrical systems and the downside of solid circuit voltage regulators as opposed to the factory style points and coil units with thermistor controls.

I may be speaking out of turn, but this posting seems rather far from the topic at hand. 

There were no fusible links in Mustangs until 1970, with the possible exception of convertible top wiring, which typically used circuit breakers.  The resistor wire for the alternator lamp is distinct from the resistor wire for the coil.  It isn't clear when you start talking about the resistor wire being a service item which wire you are referring to.  I found it hard to follow your issues and how it relates to the original poster's issues. 

I apologize in advance; I'm not trying to dis-respect you, only trying to understand the post within the thread.

[69cobrajetrugae2]

Randy, I appreciate your kindness and respect with regard to the "Left/Right/Right/Left glove slap you so deftly administered to me, but after 20 years of marriage to a 6 foot Irish gal that has been known to go from 0 to beeatch in 2 seconds flat I am immune to punishment deserved or not.

The first picture shows a knot below the round terminal which I assume to be a fuse link.  If it is not a fuse link, where or what devise protects the main power feed to the fuse box?

The attached schematics appears to show the resistor wire in service as follows.

Resistor wire 16 from hot side of ignition to a resistor wire splice wire 30 to one side of the charge indicator bulb.

Wire 904 is the case ground for the voltage regulator when grounded the charge indicator bulb circuit is complete.

After the splice 16A goes to the firewall connector.  On the other side of the connector 16 is the resistor wire voltage supply to the coil.

When the starter motor circuit is activated wire 262 from the hot side of the starter relay starter side is spliced at the firewall connector to resistor wire 16 which provides full line voltage to the coil for cold starts, when the starter motor circuit is terminated the additional voltage is terminated.  It's not really full line voltage when the starter motor is activated since 20 inches or so of resistor wire is in the series circuit to the coil, but given the 61 inches of the total length of resistor wire it's not much of a drop, current wise.

[midlife]

Randy, I appreciate your kindness and respect with regard to the "Left/Right/Right/Left glove slap you so deftly administered to me, but after 20 years of marriage to a 6 foot Irish gal that has been known to go from 0 to beeatch in 2 seconds flat I am immune to punishment deserved or not.

The first picture shows a knot below the round terminal which I assume to be a fuse link.  If it is not a fuse link, where or what devise protects the main power feed to the fuse box?
That knot represents an OEM splice.  Nothing protected the main power feed to the fuse box.  Believe it or not.  Surprisingly, most shorted harnesses I've seen are due to shorts in the neutral safety switch lines (32) or ammeter lines and not main power. 

The attached schematics appears to show the resistor wire in service as follows.

Resistor wire 16 from hot side of ignition to a resistor wire splice wire 30 to one side of the charge indicator bulb.
One side (wire 30) of the alternator lamp is the RUN-only line, and teed off before the resistor wire.  The diagram is correct.

Wire 904 is the case ground for the voltage regulator when grounded the charge indicator bulb circuit is complete.
What the schematic fails to show is a second resistor wire, 15 ohms, that ties to ACC power on one side and to the other side of the alternator lamp bulb.  This other side goes to the voltage regulator.  This provides a signal to the VR to stimulate the VR in case the bulb fails; an almost fail-safe safety device. 

After the splice 16A goes to the firewall connector.  On the other side of the connector 16 is the resistor wire voltage supply to the coil.
Correct

When the starter motor circuit is activated wire 262 from the hot side of the starter relay starter side is spliced at the firewall connector to resistor wire 16 which provides full line voltage to the coil for cold starts, when the starter motor circuit is terminated the additional voltage is terminated.  It's not really full line voltage when the starter motor is activated since 20 inches or so of resistor wire is in the series circuit to the coil, but given the 61 inches of the total length of resistor wire it's not much of a drop, current wise.
Nope.  When 262 is activated, the starter relay sends a signal to the firewall plug where the pink resistor joins the coil out line (16) as you suggest.  The pink resistor wire acts as a choke to handle any voltage differences between the 262 line and the RUN-only line generated by the ignition (typically 1-2 volts difference).  Once the starter signal cuts off, a 9 V or so at the starter solenoid is simply ignored as there is no path for that voltage to go to ground.  There is no series circuit per se when the starter motor is activated. 

Don't take as gospel this set of schematics.  The Osborne Electrical Assembly Manual has it correct, and I have reverse engineered every Mustang harness by taking them completely apart. 

[69cobrajetrugae2]

Thanks for confusing me Randy but I see your point.

Is 16A the resistor wire and 16 standard wire?  I have a unmolested 65 dash harness and the pink resistor wire is located at the ignition switch pigtail and the gauge harness did not have the resistor wire, is the gauge harness supposed to have the resistor wire?

I measured the resistor wire at 61 inches in my stock harness and insofar as I'm aware, that is the correct length for 1.5 to 1.6 ohms of resistance which it does have.

[midlife]

Thanks for confusing me Randy but I see your point.

Is 16A the resistor wire and 16 standard wire?  I have a unmolested 65 dash harness and the pink resistor wire is located at the ignition switch pigtail and the gauge harness did not have the resistor wire, is the gauge harness supposed to have the resistor wire?

I measured the resistor wire at 61 inches in my stock harness and insofar as I'm aware, that is the correct length for 1.5 to 1.6 ohms of resistance which it does have.

Yes, the pink resistor wire should "begin" with a male bullet plugged into the ignition pigtail (or the rally pac if you have one) and the other end should be on the passenger side of the engine gauge feed firewall plug.  On the other side of the firewall plug is the engine gauge feed harness, which contains wire 16.  Wire 16 is a standard copper stranded wire. 

[69cobrajetrugae2]

The 69 ford manual resistor wire maintenance procedures. 

I do not possess a 65/66 Ford service manual but I will assume that the resistor wire check is the same for the 65/66/67/68.  I was informed by an old Ford mechanic that the resistor wire can and do fail both ways insofar as providing too much or too little resistance.