Hot Wire a '68 Mustang?

  • Thread starter Big Block
  • Start date
  • #51
Ranger Mike
Science Advisor
Gold Member
2,141
207
Averagesupernova was kind enough to supply the wiring diagram.
Let us start at the battery..one side is ground ( triangle like symbol) to other is the hot (+ ) side. It is connected to the starter solenoid or relay with a big number 2 cable bolted to a huge lug. On this lug are two additional wires..see diagram..625 that runs to your Ammeter and 37 (yellow) that runs to junction connection where one side splits off to the alternator (37 red) one wire runs to the main connector and wire 654 blue one wire runs to the Ammeter.... THRU and fuse or fusible link as indicated just after the junction...) The ammeter is a meter that indicates if the alternator is charging and in order to work it must be in series or in line with the circuit so the alertnator puts out voltage (V=IR) and the current is displayed on the gage.

Back to the STARTER - the starter has one ground wire ( triangle like symbol) and one large number 2 wire connected to the other side of the starter relay.
The starter relay is just a switch activated by 12 volts supplies to the S terminal via the 32 wire. The 32 wire is activated in the turn and hold position of the ignition key. If every thing is operating correctly, when you jump 12 volts to the S terminal, it connects the switch and the starter should spin..like wise if you connect the 12 volt number 2 cable from the battery directly to the large number 2 cable the starter should spin.
The I terminal on the starter relay ( wire 262) is connected to the ignition key ( when key is in the ON position..( when your radio plays) and is also connected to the + side of the ignition coil. ( there is also an Accessory position on the ignition key, opposite of the On position..used for accessories like the radio.This was done to keep idiots from burning out points and ignition coils when they left 12 volts running to these ignition parts for hours while they were trying to get into Mary Jane rotten crotch's pants at the drive in movie).
anyway, you can hot wire the car by simply jumping 12 volts to the + side of the coil and actuating the starter by jumping the two large number 2 cables...
now you know..
P.S. don't call be if you get caught boosting some ones car with this technique..
rm
 

Attachments

  • #52
37
0
Good one rm. You made me laugh with the line about the guys burning out their points and ignition coils while trying to get into mj's "ro__en" crabby cake. A sense of humor...I like that.

It all makes sense now the way you, Averagesupernova and Nucleus have explained it (along with the wiring diagrams). I feel confident now with all this ammo (information) that I can trace the proper wires and find the burnt solution.

I will troubleshoot this long weekend, and post back with the results. Have a great weekend guys.





__________________________________________
Keep her between the ditches, 10-4, over and out
 
  • #53
37
0
Well I thought that some "HOOO-RAW's" would be in order, but it's still premature. I must say that this problem is a defiant one - right to the bitter end!

Progress Report:
I have been unable to locate the yellow "shunt" wire (#37) under the hood. Next move remove the instrument cluster and check under the dash as well as the constant voltage regulator.
I have bypassed the alternator gauge by wrapping the alternator wires together and insulating with electrical tape (that is HD "live" black wire and the black return wire. The oil pressure gauge has also a HD "live" black wire with a red-white return wire).
I also found 3 wires under the hood that have no continuity at the connector (2 red, and 1 white-red). These are for the coil and oil sender unit, and appear just after a 'disconnect block' of spagetti-like wire. I have spliced and by-passed the bad sections, but the main red still has no continuity.
"Results =
The "idiot alternator light" on the dashboard comes on when I hook up the battery terminals...ignition is in the OFF position. The light remains "ON" even when ignition is set to "ACC., ON or OFF"....Bizz-arrro!...

Q: When removing the speedo cable (from the back of the instrument cluster) there is a 5/8" locking nut holding the cable in place. As I can only feel my way (can't see a damn thing inside there), is the locking nut totally removed with cable still attached, or is the cable detachable from the nut?
 
  • #54
Averagesupernova
Science Advisor
Gold Member
3,658
645
Without actually physically looking at your car I don't think I can be of much more help without continually repeating myself. Do you have a reason to believe that the diagram that has been posted on a link that nucleus was kind enough to provide is not an accurate representation of your car? If you believe that diagram is correct then why do you continue to mess around under the dash when the diagram clearly shows that the harness can be completely disconnected from the passenger compartment and provide continuity from the battery to the alternator? When troubleshooting we always try to simplify and isolate. You are doing the opposite.
 
  • #55
Ranger Mike
Science Advisor
Gold Member
2,141
207
speedo nut is permanently secured to the cable..simply unscrew it..we did this a lot in the old days to ' save mileage"..i f the speedometer was ' jumping around " when at speed, now is a good time to lubricate the cable..it pulls out of the shielded cable and get some speedometer lube at NAPA or Autozone..


ref: trouble shooting..i think you have spliced into a live 12 volt wire ..that is why the idiot light stays on..this should only be on when ignition key is at "on" position...you need to fix this..

I also found 3 wires under the hood that have no continuity at the connector (2 red, and 1 white-red).


Do they have 12 volts with key in ON position?

These are for the coil and oil sender unit, and appear just after a 'disconnect block' of spagetti-like wire. I have spliced and by-passed the bad sections, but the main red still has no continuity.
 
Last edited:
  • #56
212
0
I'm not sure if an answer was given regarding hot wiring the 68, but in case it wasn't, here's how.

The start relay has four posts (shown below), with post #1 on the far left, post #2 on the bottom left, #3 on the bottom right, and #4 on the far right.

[PLAIN]http://www.publicityx.com/major/cart/cart/images/iginition/5678fordstartersolenoid.jpg [Broken]

Use a piece of wire to connect post #1 to #3; this will act as if the ignition key was in the "RUN" position. Use a screwdriver to bridge post #1 to #2; this will act as if the key was in the "START" position. Once the engine fires up (if all you're wiring is good), remove the screwdriver and the car should run.

If it's been determined that there is an issue with the ignition system, then I'll read up and give my $0.02 if I have any (as my name might suggest, I have a lot of experience with the 67/68's :wink: )
 
Last edited by a moderator:
  • #57
37
0
Thanks for your input 6Stang7. This is perrr-fect. Just what I was looking for.
bb.
 
  • #58
37
0
Averagesupernova, Nucleus and Ranger Mike,

Is this the 'Holy Grail' that we have been looking for? The elusive, external shunt wire!. If yes, give me your feedback. If no, I'll keep looking.



IMG_0158_1024.jpg


IMG_0159_1024.jpg


_______________
No Guts - No Glory:cool:
 
  • #59
Averagesupernova
Science Advisor
Gold Member
3,658
645
Beware. The jumper being put between 1 and 3 does a little more than bypass the ignition switch. It's purpose is to bypass the ballast resistor on points ignition systems during cranking. When the starter is cranking the battery voltage is pulled down considerably. Normally the ballast resistor drops about 6 volts so the coil is actually running on 6 volts during normal running. It is designed for this. For the few seconds during cranking the ballast resistor is bypassed by the terminal 3 in the diagram in post #56. This gives easier starting due to a hotter spark. This is not a problem for a few seconds during starting. However, your coil will not handle it for very long.
-
I don't see how this info can be very useful to you Bigblock since you have proven many posts ago that the exact thing described in post #56 does not cause the starter to turn on your mustang. You are back where you started already and my advice from several posts ago still stands.
-
Edit: Posted at about the same time Bigblock.
-
The diagram previously posted should be enough to go on provided you have no reason to believe it is wrong. It is more application specific than the diagram you posted in #58.
 
  • #60
37
0
Averagesupernova,

According to your previous posts #46, #48 and #50, I am looking for a (#37) yellow "hi-lighted" wire (as in the posted diagram) which acts as an external shunt to the ammeter. Please examine post #58 in closer detail. It has the external shunt shown in the diagram. Isn't the external shunt what I'm looking for......
 
  • #61
Averagesupernova
Science Advisor
Gold Member
3,658
645
Yes the external shunt is what you are looking for. Why are you dragging a new diagram into this? The diagram in this link:
http://mustangforums.com/forum/classic-mustangs/596726-amp-gauge-wiring.html
-
shows it just fine. In fact it is in better detail. If this wire #37 is intact you will have power at the large terminal on the alternator even with the connectors on the firewall unhooked. This is where you need to be looking. I don't know what color it is in real life. I know it has to carry complete charging current so I would say back in the day with the size charging system that car had possibly a #8 wire.
-
Edit: Do you have a reason to believe the diagram in the link I gave is inaccurate?
 
  • #62
37
0
Averagesupernova,
Had work I had to attend to. This is the status so far.

I have completely rebuilt the alternator wiring harness-brand new (including the shunt). I have power to both sides of the ammeter (unlike in posts #12 and #17). Also, I have power to the large lug (#37) at the alternator (reference post #60).

Although I did check the ignition switch wiring with a continuity check their was 1 female pin hole (B, for #37) that was brown around the edge. So, I'm buying a new ignition switch wiring harness-just to be safe...

BTW, how does one place a picture in the left-most margin under your name "Big Block"?...

P.S. The wiring diagrams are just fine, but the wire color codes are different.
 
  • #63
Averagesupernova
Science Advisor
Gold Member
3,658
645
Ok so you have replaced a significant part of the wiring in question. What specifically is not working on your car now?
 
  • #64
37
0
Averagesupernova,
So, I'm buying a new ignition switch wiring harness-just to be safe...

BTW, how does one place a picture in the left-most margin under your name "Big Block"?...

P.S. The wiring diagrams are just fine, but the wire color codes are different.
Results = No power:
. at the ignition switch (or cranking)
. no courtesy kights
. no radio
. no instrument panel lights
. no parking or headlights
 
  • #65
Averagesupernova
Science Advisor
Gold Member
3,658
645
Start at the connector on the firewall from the outside. Verify you have power on the pins you believe you are supposed to. Then go inside and do the same thing. There is most likely just ONE connection that is open. The test from the outside to the inside should show this up.
-
Refer to the diagram I linked in post #61. There is a node of 4 wires next to the firewall connector coming together in which one of them is #37 shunt hi-lighted yellow. The wire that goes through the connector and is labeled 37 which then goes off the diagram is most likely the one you need to follow.
 

Related Threads on Hot Wire a '68 Mustang?

Replies
2
Views
2K
  • Last Post
Replies
3
Views
3K
  • Last Post
Replies
1
Views
3K
  • Last Post
Replies
2
Views
356
  • Last Post
Replies
1
Views
3K
  • Last Post
Replies
2
Views
509
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
6
Views
4K
  • Last Post
Replies
4
Views
2K
Replies
2
Views
1K
Top