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Howdy. I'm 90% done (well, I thought so) installing my Pertronix Ignitor II and found that the '75 530 doesn't have a ballast resistor, rather a resistor wire (clear insulation, 0.9Ω) going to terminal 15 on the coil along with one red/black wire and of course the black ground wire for terminal 1.

The instructions say that either the ballast resistor should be removed or the resistor wire bypassed. Problem is that I cannot find where the resistor wire comes out of the harness. I've checked all of the places where wires exit and see nothing that has the clear insulation. I have the blue binder that covers the 1975 530i exclusively so as to remove confusion with the electronic ignition and it's been no help. The FAQ doesn't cover removing the resistor and it covers a '78 530i, so that doesn't do much for me.

Anyway, I'm wondering where that wire goes as I need to bypass it with another wire. I don't want to cut open the harness. Maybe I'm looking at it wrong, but I'm at a loss right now.

Thanks.

Chris,
Yeah, the 528i resistor pack that attaches to the right fender was definitely a change from the 530i. Unfortunately, I can't quite remember what the original 530i resistor wire actually looked like. However, I saved everything and might be able to look in that box if you really end up being stuck.

Re-reading the instructions on my computer after seeing a couple of installations where people left the resistor wire in tact with no issues, I noticed it said "recommended installation" and below the part where I stopped reading it says, "alternate installation" which suggests it's possible to leave the resistor in the circuit.

wkohler wrote:Howdy. I'm 90% done (well, I thought so) installing my Pertronix Ignitor II and found that the '75 530 doesn't have a ballast resistor, rather a resistor wire (clear insulation, 0.9Ω) going to terminal 15 on the coil along with one red/black wire and of course the black ground wire for terminal 1.

The instructions say that either the ballast resistor should be removed or the resistor wire bypassed. Problem is that I cannot find where the resistor wire comes out of the harness. I've checked all of the places where wires exit and see nothing that has the clear insulation. I have the blue binder that covers the 1975 530i exclusively so as to remove confusion with the electronic ignition and it's been no help. The FAQ doesn't cover removing the resistor and it covers a '78 530i, so that doesn't do much for me.

Anyway, I'm wondering where that wire goes as I need to bypass it with another wire. I don't want to cut open the harness. Maybe I'm looking at it wrong, but I'm at a loss right now.

Thanks.

Stand back while I whip this out....

If you look on page 61-0/9 in the Writ Of Common Wisdom (530i Blue Book), look at item 96, right next to the distributor in the diagram. It is where the GN wire from the fuse box (pin #4) is hastily soldered onto and becomes the resistor wire. If you disconnect the harness at the coil and stretch it out straight, the splice is exactly 100cm from the tip of the spade connector at the coil. Or, 8cm downstream from where the harness branches off to the starter.
So the bottom line is pin 4 (GN) on the fusebox/engine harness plug. I suggest to take your connection from above the soldered point by removing the wrap on the harness up to that measurement, cut the resistor wire, remove it. Splice and run a new GN wire to the harness of the Pert harness connection, re-wrap harness. Cleanest install. Otherwise you have to run a piggyback. Ugly install.

I looked at the diagram you referenced and that's pretty much what I'm seeing. Verified it with a continuity test.

I guess that makes sense it would be spliced in inside the harness. I really don't want to remove the wrap on the harness as it's really nice and would never be the same being that meshy nylon wrap, though I could probably come up with something. Thanks for the direction.

There should be a second wire from the starter engine to the coil + (mine has, but is carburetted). You might disconnect it from the starter engine and connect it some switched 12V source, perhaps something related to the injection that might be at hand. Or just pull an extra wire between coil and a switched 12V.

I would, of course, try first if things work or not the way they are.

I got everything back together Monday night. I decided to leave the wire in the circuit for now since my meter showed 9 volts during cranking and that's above the minimum voltage requirement for the Pertronix. Runs great. Due to an issue of my distributor being 180º from the one in the diagram in the Timing FAQ (I did not touch it at all), I had some issues getting it started, so I did put the points back in, which actually in the end was good. Once it was setup properly (at least for this car), it fired right up and I drove it, finding the same drivability issues I had before. I was a bit disappointed, but I put the Pertronix back in and all of that went away and the idle was much improved. I definitely got a crash course in how this stuff works which is nice, yet frustrating.

Of course, now that everything is clean and together, the high pressure power steering hose decided to make a mess of things, so until the new one arrives from Germany, it's making a mess of my garage.