Black_69_FB 49 Report post Posted June 10, 2010 I am building up to tackling the wiring on the Mach here in a few weeks, so I've been looking at the factory wiring diagrams to familiarize myself with them. Never done this before, so bear with me. I thought a good place to start breaking things down would be the ignition switch. So, looking at the diagram I see 6 positions, which are labelled B, A, C, S, PO, & PO. Wondering if anyone knows what these stand for? My best guesses are: B - battery? Yellow wire, should be constant hot... able to trace source back to black/yellow wire coming from alternator harness on BAT+ side of solenoid. A - Accessory/run. Black wire with green stripe feeds to fuse block for accessory hot. S - Start - Self-explanatory. Red wire with blue stripe eventually ends up on starter solenoid. C - ? Pink resistor wire terminates here along with a green wire with red stripe that appears to tie into the voltage regulator as well as the + side of the coil, and the instrument cluster feed. This is where I got lost as far as when it is hot. PO (x2) - ? No idea what this stands for. Purple wire feeds one side of the brake warning switch on the distribution block. Assuming this is accessory hot or my warning light would have stayed on always. Any corrections/confimations/additions would be appreciated. Quote Share this post Link to post Share on other sites
Black_69_FB 49 Report post Posted June 10, 2010 I am building up to tackling the wiring on the Mach here in a few weeks, so I've been looking at the factory wiring diagrams to familiarize myself with them. Never done this before, so bear with me. I thought a good place to start breaking things down would be the ignition switch. So, looking at the diagram I see 6 positions, which are labelled B, A, C, S, PO, & PO. Wondering if anyone knows what these stand for? My best guesses are: B - battery? Yellow wire, should be constant hot... able to trace source back to black/yellow wire coming from alternator harness on BAT+ side of solenoid. A - Accessory/run. Black wire with green stripe feeds to fuse block for accessory hot. S - Start - Self-explanatory. Red wire with blue stripe eventually ends up on starter solenoid. C - ? Pink resistor wire terminates here along with a green wire with red stripe that appears to tie into the voltage regulator as well as the + side of the coil, and the instrument cluster feed. This is where I got lost as far as when it is hot. PO (x2) - ? No idea what this stands for. Purple wire feeds one side of the brake warning switch on the distribution block. Assuming this is accessory hot or my warning light would have stayed on always. Any corrections/confimations/additions would be appreciated. Quote Share this post Link to post Share on other sites
magician 13 Report post Posted June 11, 2010 PO= prove out From another forum...Better than I can explain it It provides a temporary ground to all warning lamps to test them. After the ignition is released back to the run circuit from start the warning lamps revert back to their own ground paths (switches, sensors,etc.). Remember, path of least resistance. When the ignition switch provides the temporary ground, the warning lamps take it. C=coil I have no idea if thats what it stands for but you are correct in its function. Green /red supplies 12 to coil in the crank position and then reverts to 6-8 volts for the run position on the resister wire. Google 69 wire diagram ,there is a free one online somewhere but I forget where. Quote Share this post Link to post Share on other sites
magician 13 Report post Posted June 11, 2010 PO= prove out From another forum...Better than I can explain it It provides a temporary ground to all warning lamps to test them. After the ignition is released back to the run circuit from start the warning lamps revert back to their own ground paths (switches, sensors,etc.). Remember, path of least resistance. When the ignition switch provides the temporary ground, the warning lamps take it. C=coil I have no idea if thats what it stands for but you are correct in its function. Green /red supplies 12 to coil in the crank position and then reverts to 6-8 volts for the run position on the resister wire. Google 69 wire diagram ,there is a free one online somewhere but I forget where. Quote Share this post Link to post Share on other sites
Selder 22 Report post Posted June 13, 2010 Hello, Last week I made this '69 Mustang alternator drawing below (with 'Paint'). You can't see it here but the resistor wire comes from the ignition switch © en goes to the + side of the coil. There's also a brown wire coming from the starting relay and going to the + side of the coil. This wire goes throught the firewall to the square connector and comes out of the firewall together with the resistor wire. It only gives 12V in crank position (S). The green-red wire also comes from the 'C' plug, going to the 'S' terminal on the voltage regulator. The green-red wire activates the 'field relay' giving current to the alternator field. A running alternator has no output when there's no current in his field coil ! When the battery voltage is too high the voltage regulator disconnects the field coil of the alternator ... and so on ... I hope this can help you ... Greets, Hans. Quote Share this post Link to post Share on other sites
Selder 22 Report post Posted June 13, 2010 Hello, Last week I made this '69 Mustang alternator drawing below (with 'Paint'). You can't see it here but the resistor wire comes from the ignition switch © en goes to the + side of the coil. There's also a brown wire coming from the starting relay and going to the + side of the coil. This wire goes throught the firewall to the square connector and comes out of the firewall together with the resistor wire. It only gives 12V in crank position (S). The green-red wire also comes from the 'C' plug, going to the 'S' terminal on the voltage regulator. The green-red wire activates the 'field relay' giving current to the alternator field. A running alternator has no output when there's no current in his field coil ! When the battery voltage is too high the voltage regulator disconnects the field coil of the alternator ... and so on ... I hope this can help you ... Greets, Hans. Quote Share this post Link to post Share on other sites
Black_69_FB 49 Report post Posted June 13, 2010 Thanks guys. Every bit helps. I was looking at the wiring diagram today and I think I found a mistake. Or else the harness I'm looking at is wrong, but it appears to be original & intact. On mine, the wire running from the column connector to the emergency flasher is white/red striped. On the diagram, it shows BLACK/red. Quote Share this post Link to post Share on other sites
Black_69_FB 49 Report post Posted June 13, 2010 Thanks guys. Every bit helps. I was looking at the wiring diagram today and I think I found a mistake. Or else the harness I'm looking at is wrong, but it appears to be original & intact. On mine, the wire running from the column connector to the emergency flasher is white/red striped. On the diagram, it shows BLACK/red. Quote Share this post Link to post Share on other sites
Black_69_FB 49 Report post Posted June 14, 2010 Well, through a twist of fate I found my Osborne wiring manual tonight (which had been MIA so long I had forgotten I had it). It cleared things up for me. Here is what I now know about the ignition switch: B - Battery. Constant hot. Provides power to switch via yellow wire. A - Accessory. Hot when key is in both ACC & RUN positions. Feeds power to fuse block (black wire, green stripe) for accessories. S - Start. Provides power to starter & coil when key is in START position. C - Coil. Provides power to coil in RUN position. PO - Prove Out. Hot when key is in START position. Tests warning lamps, just like magician said in his post. I know this is probably old hat to some, but it's something I really needed a refresher on. Maybe this thread will help somebody out down the road. Quote Share this post Link to post Share on other sites
Black_69_FB 49 Report post Posted June 14, 2010 Well, through a twist of fate I found my Osborne wiring manual tonight (which had been MIA so long I had forgotten I had it). It cleared things up for me. Here is what I now know about the ignition switch: B - Battery. Constant hot. Provides power to switch via yellow wire. A - Accessory. Hot when key is in both ACC & RUN positions. Feeds power to fuse block (black wire, green stripe) for accessories. S - Start. Provides power to starter & coil when key is in START position. C - Coil. Provides power to coil in RUN position. PO - Prove Out. Hot when key is in START position. Tests warning lamps, just like magician said in his post. I know this is probably old hat to some, but it's something I really needed a refresher on. Maybe this thread will help somebody out down the road. Quote Share this post Link to post Share on other sites
