OK, here goes. I don't drive my 71 GS much. Start it every once in a while. A 455, MSD set up. BIG cranking amp battery. Started it the other day, the generator light came on bright at first as usual, then stayed on. Dim. Checked and charged the battery. Started up just fine again, and the light went out as it's supposed to. Until I turned it off and started it again. This time the light stayed on bright. So... under the hood I go. Now I did not put my distributer, the coil, nor the MSD6AL in my car. But I found an interesting wire from the coil to the distributer that doesn't seem to do anything and find it odd that the car still starts and everything still seems to work. I've moved the car but I have not driven it yet for fear of not making it back. ( I'll try to get a picture here) The wire looks like it's supposed to have a fuse in it. You know, one of those in line fuse type that sort of twists to lock on. This wire and maybe(?) a dead cell in my battery is all I can figure. Help? Chris
Chris, I think your charging light problem has nothing to do with that wire. If the light comes on, the first thing I would do is to put a voltmeter across the battery with the engine running. It should read 13.8-14.6 volts. If it reads 12 volts or so, the alternator is not charging, and that's why the light is on. What kind of alternator are you using? Is it the original one using the external regulator? If so, consider upgrading to an internally regulated later model alternator. They do a much better job of charging the battery. This is an excellent article: http://www.buickperformance.com/alternat.htm BTW, there should be only 2 wires going to the coil. They come from the MSD6AL box. One wire is orange, and goes to the coil +, the other is black, and goes to the coil -. It's hard to see where that wire from the coil ends at, in the picture. Some people mistakenly try to run a wire for a Tach from the coil. That is wrong, there is a tach output on the MSD box. The MSD box puts about 450 volts to the coil. It looks as if you are using an MSD billet distributor. The green/violet magnetic pickup wires will plug into a harness going to the MSD box. Some people use a points distributor, to trigger the box, the single wire coming out of the distributor, would go to the white wire in the MSD box. Maybe the previous owner never removed that wire, when he converted from points. I don't know what that wire is, and I think you do not need it. I would remove it, and I don't believe it has anything to do with your charging problem.
Larry, Thanks. I'll check a few things tomorrow, Sunday. My mysterious wire looks to end at the distributer. There is a wire loom there, and the other end of that wire seems to come from it. Your're right on the money about the tach. I had to use a tach adapter from MSD and it works fine. I'll let you know, and thank you again. Just to let you know, (as not to waste your time) I did look through some past threads but couldn't find anything helpful there, except a scare or two. Chris
I suspect that the wire you referenced was the wire containing the diode for the alternator. The old wiring allows sufficient current through the alternator bulb to drive the ignition. The installation contains a diode which allows current to drive the bulb, but when the ignition is turned off, the diode prevents the ignition from drawing the necessary current to refuse to turn off. If this diode is shorted, the light may stay on, without a charging problem existing. Using a multimeter, check for a reading similar to a wire, indicating a short. A good diode will have approximately 10 times the resistance in one direction as in the other. You can also use the diode checking section to check this. Ray
Ray, Doesn't the diode go inline with a wire between the regulator and alternator? The wire in the picture (1st picture) appears to be attached to the - side of the coil, and end at the base of the distributor. o No:
Actually, yes, but the light connection does as well. The diode can go on the alternator end or the regulator end. The result is the same. Early style ignitions drew more current than they do now. The circuit for the indicator light allows sufficient current to flow to operate a good late model ignition, requiring the diode to prevent run on when this combination is used. The picture did not appear on my display, regardless of the number of times I attempted to see it, even with DSL. The wire going to the (-) side of the coil is the driver wire from the ignition. It is the wire the ignition uses to control the coil. There are several possibilities for what the wiring calls out. Since the original thread indicated a gen light problem, I addressed that problem. Since the light, like any electrical circuit, requires a voltage and ground to operate, anything providing both will operate it, correct or incorrect. I can address questions on these systems, and welcome the opportunity to do so. Ray
Wow. Gentlemen, needed to run out of town at the last minute Friday night. I promise to look at, now, a few more things then I thought I was going to. I'm the novice, but will keep you informed. Yes, MSD distrib. and coil. GM alt.
OK, you can't see the picture. He has an MSD 6AL. On the MSD CD ignitions, the only wires that should go to the coil, come from the box. Since the box applies 450 volts to the coil, nothing else should be attached to the coil. In the picture, you see a wire coming off the - side of the coil, and it seems to lead to the base of the distributor, can't tell what it is attached to. There is also something inline with the wire, looks more like a short fuseholder to me. I think he has a straight foward charging problem, either alternator or regulator based. The wire in the picture serves no purpose that I can tell.
Thanks Pat, that's the one. I can't figure out what that wire is there for. The only wires that should attach to the coil on an MSD system, come from the box. I wanted Ray to see that wire from the - side of the coil, going down to the base of the distributor. Can you see the picture Ray? What do you think?
Larry, In the 1st photo that wire is plugged into the white piece.Looks like a fusible link to me... Pat
Yes it does look like a fusible link, but what it's doing there, I don't know o No: It looks like it goes from the coil to the base of the distributor. The white piece looks like a glass type fuse holder, and it's just laying there.
In this configuration, it is possible that this wire is intended as a noise suppressor. I appreciate the confirmation that it goes from the coil negative to ground. If this is the case, I am not sure of its purpose, if that is the case. The post indicating that the only wires to the coil come from the coil is correct. These ignitions provide some 400-500 volts to the coil, which is the method of increasing the coil output. This voltage comes from the ignition box, using the trigger from the distributor. I also agree that the apparent problem with the alternator light may be a charging issue, or one related to the light. Suggestion: access the connection instructions from MSD, assure that the ignition is properly connected, and go from there. Since the ignition is operated by the switch, as is the alternator light, it is possible that the problem is related to the ignition, but some simple troubleshooting will determine that. Once we are sure of the hookup, I can walk you through some simple checks. Let's start with the basics, and keep it simple. Something else to try; reconnect the ignition as the factory did, eliminating the MSD ignition. Observe the operation of the alt light and advise. We'll get this resolved. It is only somewhat more difficult since I cannot lay hands on the problem. Ray
I'm back and I'm still confused. Everything, and I mean everything, checked out fine. The mystery wire is still a mystery, but I've gotten over that for now. Started the car. Light is on. Ran at idle for about 20 mins. Turned off the ignition. Cranked it up again and no light. 8 miles later, still no light. Pulled back into the garage shut it off and started it again... no light. You think maybe the battery has a bad cell that charges itself? Remember, when this first started I needed to charge my battery. Which I did. I've never had a problem with this generator light. (the car did sit dormant longer than usual) Still, a load test of the battery shows OK. The battery didn't show that little green light but still started the car when this whole thing started. The only thing I can think of with that mystery wire, if it makes any sense, is that it was used for the tach. It may have gotten the tach to light up and bump but not work. I knew the tach with the MSD ignition would need a tach adaptor, but I'm thinking the person who dropped my motor may not have known that. Do I just suck it up, buy a new battery and see what happens? Chris
