68 gto rear defogger
 

Just bought a complete rear defogger kit for the 68 gto comes with switch ,harness ,grille and rear defogger the problem is that I can not find a wiring diagram for the connection and I believe something is missing the switch has a brown white and purple wire I believe the brown needs a 12 volt feed wire but now the purple wire goes to the rear defogger my problem is that there is a connector with the white and purple wire and I don't have a connector for that just the purple wire connector if someone can help with a clear diagram it's appreciated and thanks

Sec 15 of your 1968 Service Manual; Best I have...
https://live.staticflickr.com/65535/...39e7b9d0_c.jpg

Thanks for the diagram but the plug with the white and purple wire together I don't have I just have the purple wire with the single connector at both ends the plug with the white and purple wire looks like a double connector.

The purple wire is for high speed. The white wire is a resistance wire for low speed. The white wire is spliced into the purple wire within the under seat harness feeding the defogger.

The purple & white wires to the switch have a double male terminal. The wire feeding back to the defogger has a double purple & white female terminal at the dash end and a single purple wire terminal at the defogger.

https://forums.maxperformanceinc.com...6&d=1617235726

https://forums.maxperformanceinc.com...7&d=1617235745

Do you know where I can get that double plug to single plug for the rear defogger from the switch to the under seat wire

My question is; does one end of your underseat wiring harness have a white and a purple wire and does the other end just have a single purple wire?

No I don't I have the purple wire that goes under the seat from front to back and from the switch I have the two prone connector which I can't hook up the purple wire to because it's one prone seem to me like a connector is missing if it helps I will try to take pictures of it later and I appreciate your help.

In cases like this, you can use separate connectors or find a suitable (similar) replacement.
There are several vendors that deal with Packard Connectors, it's just daunting to look through all the e-catalogs.

Here is one example;
https://ceautoelectricsupply.com/ind...rd-connectors/

So if I get the connector I would just run the purple and white wire to one and connect it to the purple wire connector.

You need purple and white (2) wires for the under seat harness. The white wire, for low speed, is a resistance cloth covered wire similar to the one that drops the voltage down to your coil. The purple wire, by itself, will work, but you will have high speed only.

I do have a bare double wire connector housing for the underseat harness.


https://forums.maxperformanceinc.com...8&d=1617304938

That looks like what I need I am trying to send you a picture of my connector if I can figure out how to send it to you hope the pictures went thru let me know and thanks.

Just a suggestion. Try contacting M&H, Lectric Limited or American Aoutowire. They might have the exact heater harness you need.

Will the connector you have fit into mine if not I will try m&h

You will need a new harness for the defogger to work correctly. It should be similar to what I pictured above. Depending on what plugs are used with the new harness will determine what plug you will need at the switch end. But I'm willing to bet it will be like mine.

Hey Ed, I'm trying to create a new harness where the double wires Purple/White are behind the switch connector, where can I purchase this white resistance cloth covered wire? Also what AWG is the wire (18 AWG?) and is it copper or Nichrome, certain the purple wire is 16 AWG, and how long should it be before it ties to the one purple wire?

I apologize for getting back to you so late. I finally dug the defogger out of storage.

The underseat harness from the switch connector to the blower motor pigtail is 11' 8".
The resistor section is 8'11".
The resistance of the white wire is approximately 4 ohms.
The resistance wire appears to be Nichrome. The purple wire appears to be 16 awg but I'd use 14 awg due to the distance involved.

After some trail and error, i was able to find some Nichrome 18 gauge and 20 gauge solid wire...unfortunately its not available in its original 7 stranded 18 gauge form. Its hard to believe no one reproduces resistance stranded wire today with PVC covering and with the white cloth urethane covering, and red and white strips, everything else is reproduced. Your correct 18 gauge Nichrome has a .42 ohm resistance per ft while 20 gauge is around .62 ohms per ft. But at any rate i used some black shrink wrap tubing giving it a good PVC covering and ran the resistant wire to 50" before it meets up with the main wire which drops the voltage to around 8-9 volts, enough to provide slow speed. Works perfectly!!