No spark and i can only get 5V at the coil.
"The brown wire i have goes from the ballast on the fire wall to the + on the coil" The confusion here is that the brown wire that you are looking at appears to be the wire from the low voltage side of the ballast to the coil +. The brown wire that everyone is thinking of is from the IGN2 position of the key switch to either of those 2 points (usually the low voltage side of the ballast) via the firewall connector.
I think you DO have the wiring diagram in the FSM. Follow that to see if you can ID that 3 prong connector; I suspect your wiring is all hacked and cross-connected so with us not there physically, it is going to take a lot of description on your part for anyone on this end to figure out what has been hacked or crossed.
From what I've seen in the manuals is those wires and connector would go to a different parking light/signal setup than i currently have seeing as mine has the fender mounted setup.
It would be very helpful to start posting more data with each report, under the same set of conditions. Keep the - lead of the meter at the - lead of the battery at all times so that is a constant reference point. Measurements from more points is needed to find if there is a significant voltage drop and how much. Just reading at one point is not enough.
If you can, please post the voltages at:
- battery + = 12.V
- input and output from ignition switch = 12.1V
- blue wire to ballast = 10.93V
- wire from ballast to coil + = 5.1-5.5V when connected, 10.9 when disconnected
BTW, did you ever run the spark test that I described over in the /6 section? That would have separated the coil and ballast from the ECU and distributor to help you narrow down the problem area. Haven't run it yet because Im trying to make sure I completely understand the process before attempting.
BTW#2: Does this car have an electric choke? I asks as that could be one of the extra blue wires spliced in. That will load the ignition switch and cause extra voltage drop in the IGN 1 (blue wire) circuit. I would sure like to know to what parts those extra blue wires go to. One is likely the voltage regulator: flat box on the firewall with 2 leads, one blue and one green. Another blue wire should go to the blue field wire on the alternator.
It does have a electronic choke control that is fed off the box above the valve cover(cant remember the name right now) See the white wire deaqd center of the picture below connecting to the box and then a blue wire feeding that box and the vacuum switch as well.
BTW#3 One more thing to check: Make sure the brown wire from ballast to coil + connects to the low resistance side of the ballast. There is a low resistance side (about .6 ohms cold) and a high resistance side (about 5 ohms cold). If your brown wire is connected to the high resistance side, then it will drop the coil+ voltage way too much. And besides, if you have the later ECU wiht 4 prongs, you don't need the high resistance half anyway. In that case, you can just convert to a single ballast with the correct cold resistance. Here is my current layout of the ballast resistor and its been like that since I've had it. But there seems to be some conflicting diagrams in the two manuals on the orientation of the wires.
Can you take a pix of the 3 boxes on the passenger side to which these blue wire go?
I am suspecting more an more that a PO spliced several +12v loads in the engine compartment to the IGN1 circuit and that is overloading the IGN (blue wire) position of the switch.
Also, this IGN1 (blue wire) lead in the 1975 models goes via a fuse to the instrument cluster inside the passenger compartment via a fuse. Not what it powers in the cluster, but find the single fuse with blue wires in and out and pull it and see if that helps your voltage out to the ballast.
Have you considered another engine compartment harness? There is so much hacking in the present one....Yes I have but ive already picked up most of the pieces for my 5.7L hemi swap. SO if this is too much more trouble I wont even mess with it any more.[/QUOTE]
I replied to your questions above in bold.
