For those of you who want to hear the entire story. I aquired a fine old volvo that had no spark. Had numerous spare parts. Swapped out all components still no fire. Someone suggested that the thick white wire near the connector on the module could be grounding out on itself. To test this theory they told me to cut the ground wire and see if I it would spark. this is the wire that grounds the coil to stop the engine when you turn the key off. If the insulation on this shielded wire has worn through, it could ground out and stop the coil from firing. I never found out where it was grounding out, as the wire runs under the engine. but as soon as I cut it, it started. I bought this car for 400.00 and told everyone that it would only require a minor repair to fix it, as I have had four others just like it. it was clean as a whistle, had regular maintenance, garage kept, not one speck of rust, no dents, and it was driven by a woman. and only had 160k miles on it. but of the other four I had, never had one do this.

Corey

south Louisiana.

Glad to hear you got it running, but your explanation leaves me uncertain as to what actually fixed it.

1) By "thick white wire", I thought you mean the gray wire that connects to coil terminal #1. But you say the wire is, "...near the connector on the module..." The only wires I know of are IN the connector, not "near" it. Might you have cut the white vacuum line connected at the bottom of the module?

2) Because the gray coil wire doesn't "ground the coil to stop the engine when you turn the key off". In essence, it turns the coil on and off to initiate the high-voltage ignition sparks. Cutting that wire would be the same as disconnecting it from the coil. In which case the engine would not run at all.

3) I agree that if the external shielding somehow came in contact with the internal wire, there would be no ignition. But I'm baffled as to how your engine runs with the negative side of the coil no longer connected to the ignition module.

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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.

Let me also clarify that the wire in question is part of the plug. I said near the connector, because the outer shield of that wire did not go into the connector, it branched off before the module, so in my eyes it was near the connector, not in it. I will say that I suspect this harness has been toyed with, so it is possible that the way it branched off, this wiring arrangement may not have been factory.

corey

south La.

Well, let me clarify exactly which wire I cut. The harness that plugs into the module near the front left fender. (the same unit that has a vacuum line connected to it) On that harness, there is a white wire that is thicker than all the others. that wire has an outer metal covering, sort of like a t.v. coaxial cable. That outer wire covering came off of the white wire, and tied into a black wire on the same harness. But you are correct, it can't be the wire that grounds the coil, as the car still turns off as normal. But whatever that wire goes to, it was the precise solution to my problems. After each component swap out, i checked for fire. Only after I clipped this wire, did it start.

corey

"But you are correct, it can't be the wire that grounds the coil, as the car still turns off as normal."

Corey,

The wire that connects to Coil terminal #1 has nothing to do with turning the car off "as normal". It's basic to the spark generation process. But it will prevent the car from starting if disconnected (or cut).

The normal "turning off" is done by blocking the + voltage to the other coil terminal—the blue wire(s) at terminal #15.

And I'm still baffled, because I have wiring diagrams, and they show no white wire at the Ignition module. I believe the only shielded wire at the module is the "light gray" one going to Coil terminal #1. I'll check when the '87 240 gets back later.

Anyhow, I think we're talking about the same wire, but how your car can run with it cut is a mystery to me.

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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.

Bruce, thank you for outlinning that as well as you did. You hit it right on the head.

Mark