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1975 De-smog Question


Mark92131

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With the holidays, I have been wrenchng on my newly acquired 1975 Mintgrun 2002.  I have pulled off most of the easy bits (basically all the fire wall valves, relays, divertor, etc.) but would like to remove the entire smog harness.  I traced the blue harness back to the area near the fuse box, but it appears to be wrapped up with a much larger group of wires running towards the front relays.

 

1. Do I need to cut this wrap open to expose the connection to the smog harness so it can be unplugged, see picture?  Where exactly does the smog harness unplug?

 

I have read that the positive tach wire should be disconnected at fuse #12 and spliced with the resistor wire from the smog harness.

 

2. If I am running a coil (Blue or Aftermarket) with an internal resistor, do I need to still recover the resistor wire from the smog harness, or can I just run a wire from fuse #12 to the positive side of the coil?

 

3. The blue smog harness seems to have three wires connecting to the coil (red, black and green).  Do I disconnect them all and then run the wire from fuse #12?

 

4. Also, If I remove the alternator, does that give me enough room to slide out the EGR Valve and EGR Filter from under the intake manifold?

 

Thanks,

 

 

Mark92131

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If you are running a blue coil then you can (and should) replace the resistor wire with a regular piece of wire, preferably green. 

 

It has been awhile but I do remember having to unwrap some tape right by the fusebox to separate the smog harness from the car, it was only a couple inches worth as I recall.

 

On the positive side of the coil there are a pair of wires, one is the resistor wire and one is a bypass wire for when you are cranking the starter, both will go away if you replace with a blue coil and single wire, you don't really need the bypass circuit with the resistor wire especially in a warm climate such as ours so if you keep the old coil you can just use the resistor wire and remove the other one, especially if you hook it up incorrectly on the starter side your resistor wire will catch on fire as soon as you turn the car on, I have seen it happen.  I don't remember a wire in the bundle that went to the negative side but what is supposed to be there is one wire from your points, and one that goes to your tach, both are usually black.

 

HTH

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Blue coils require no resistor. You can basically remove everything in the blue plastic shield and simply have a normal wire running from the fuse box to the coil.

 

The black wire on the coil is probably the ignition wire so that stays. At a minimum you need a black wire from the ignition to the negative on the coil and a positive wire from the fuse box to the positive. There can be additional wires on the coil if you have an electronic choke or petronix ignition.

 

I do not remember having to unwrap a bunch of tape when i undid my wiring harness.

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OK, I have run into a small snag while disconnecting the smog harness from the fuse box,  Basically, I have two blue harnesses from the fuse box to the coil.  The smaller of the two houses connections to the Condensor (2), the oil pressure switch, and the "-" side of the coil. (Ignition wire or Tach?) and is wired into the wrapped wiring harness.  The larger blue harness for the smog components is wired into the back of the fuse box.  I was able to disconnect one of the wires, but the other does want to unplug from the white plastic connector.  I have damaged the wire badly and want to try to avoid further damage to the wires on either side.  Is there a trick to removing the second wire?

 

Thanks,

 

 

Mark92131

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