The shop that installed my 6AL ignition didn't put in the diode on the gen lamp wire for my '66 Malibu. After removing the dash to fix a speedo problem, I took the opportunity to put in some missing bulbs, the Gen lamp being one of them. I didn't realize at the time that the shop had taken that lamp out to remove the run on problem. When I put the lamp back in, I got the run on problem but it really didn't connect with me that the run on problem was because of my putting in the lamp and the lack of the diode.
Unfortunately, the car died yesterday while debugging the problem. I thought I was out of gas because I was low, but after filling the tank and getting plenty of gas at the carb, still a no go.
I went about debugging the ignition and I think the ignition is dead. I get .7 ohms between the two coil terminals (MSD Blaster 2) and 10k ohms between the top post and either of the two terminals which seems about right. When I trigger the ignition with the mag pickup or by grounding the white/points wire, I can measure a very small AC current across the coil terminals, around .01V (I realize that this isn't going to be accurate because the AC duration is probably much smaller than the Vmeter can accurately read). If I measure the AC Voltage from the coil top terminal, I still only get a very small voltage, and when holding the coil to dist. wire near ground, I don't get a spark no matter which trigger I use. I have 12V at both the large and small red wires on the ignition and good ground. The fact that the ohms on the coil appear to be right leads me to believe that the coil is still ok and that something in the outputs to the coil are not working right.
The msdignition.com web site says that the 6 series ignition will work down to a 5 volt supply, but will 6.5-7.5 volts on the ignition wire (small red one) cause the 6AL to fail? This is the only thing that was occuring that I can think would cause the ignition to fail. I guess the one other thing I was doing was very briefly grounding the ignition wire at the ignition switch to stop the motor. I suppose it might have cause a brief back current through the MSD ignition but the unit was operating and stopped on its own when it failed, not after doing any grounding. I'm overnighting a new one from Jegs on Monday but in the mean time, I'm wondering if there is anything simple that could be done to fix the unit if the low ignition voltage is what caused the problem, such as replacing an internal fuse or something of that nature. If so, I'll cancel my Jegs order. The unit is out of warranty at this point and I know they can't warranty every situation because cars parts can be put through a beating, but I feel a bit let down at the moment both by the shop that improperly installed the thing in the first place and by the fact that the ignition gave out without, what I would call, a stressful scenario.
Has anyone else seen an MSD 6 series ignition give out from this sort of scenario?