Condenser/Coil question

[Aultro]

Attached to the back of the coil is this condenser. It has one wire (top one) coming out of it. There is also another maybe unrelated wire (laying on the spring) that comes out from the bottom of the distributor cap. None of this is hooked up anything and the truck runs fine. does anyone know what all this is for?

67 GMC 283 3/4 ton 2wd

[Steeveedee]

The condenser should be connected to the distributor side of the coil. What color is the insulation on the wire with the connector laying in the throttle return spring?

[geezer#99]

Mysterious!
You don’t have the coil hooked up yet it runs fine!
That wire on the spring and the condenser should be hooked to the negative side of the coil.
Any other wires coming out of the distributor?
More pics would help.

[dmjlambert]

That is interesting that the truck runs. What is hooked up to the coil and can you post better pictures? The condenser is for AM radio noise suppression as I understand it. Do you know if the distributor was converted to electronic module inside or has points?

[Aultro]

Both wires are black.

The wires secured to the left terminal all go into a harness then disappear into the cab.

Don’t know if it’s been converted.
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[geezer#99]

Pop the cap off and take a pic.

[Aultro]

are these pics better? it's pouring rain in the Dayton area now.

I trimmed things up a bit with the fraying and i took a pic of the back the best that I could. sorry about the sideways pics--iPhone.

[randy500]

That condenser is not the one for the points, that one is to suppress ignition noise in the electrical system, specifically the radio. It still connects to the negative side of the coil though.

[Aultro]

what side is the negative side of the coil?


does the loose wire go to the negative as well?

[Aultro]

also what are the yellow and white wires on the coil for?

[dmjlambert]

You have me curious now. Are you saying there is nothing attached to this terminal I am pointing the arrow to, and the truck runs?

[dmjlambert]

The white cloth covered wire is the resistor wire that comes from the cab to supply voltage to the ignition system. The yellow wire comes from the starter to provide extra voltage to the ignition system during start.

The - and + markings on the coil are probably under the dust and just can't see them now.

[Aultro]

Yes and No.

I've driven the truck for two years now with no problems with nothing on that terminal and the other loose wire was just that - not connected.

Well yesterday I hooked up both the loose wires to a terminal each on the coil and tried to figure out what they are for - was told it for the radio so didn't figure it would hurt anything. Didn't try to start the truck but I turned the key to see if it helped the radio. Didn't help it but for all I know it might be a radio or other issue. But now the truck won't start. It has fuel as I just dumped 3 gallons in it.

It is hooked up right now - in the pictures - as it has been for two years but won't start. First time it hasn't started. Not sure if I maybe I shorted something out when I hooked those two up.

[dmjlambert]

OK. The + side of the coil should be hooked up to the white cloth covered resistor wire and the yellow wire. The - side of the coil should be hooked up to the condenser and the wire from the distributor. That is the wire that goes to the points in the distributor. Dust off that coil to see the + and - markings.

[Aultro]

thanks a bunch. It's stopped raining so I'll go check.

[Aultro]

the engine isn't getting any spark.

so my neighbor came over with a V meter. he found power to coil and out of the coil to the distributor.

[dmjlambert]

If the distributor wire was on the + side of the coil for some time while you were experimenting, it could have sent some high current though the points during the attempted start. The purpose of the yellow wire is to to provide a full 12V from the battery with no resistance, and the purpose of the points is to short the - lead on the coil to ground for each spark that needs to be sent. Attaching those 2 wires together without a coil in between is a direct short when the points close for each cylinder during start. So the points could be damaged or welded together. That is a typical tune-up change item anyway so probably no biggie.

There's a variety of troubleshooting items to do next, I should let the much more experienced folk here chime in.

[Aultro]

thanks for the explanation. I'm replacing the points and condenser today. using Youtube for instructions.