Rear window defroster wiring

[Ed Brock]

Hi folks,

I could use your help. We have a 1971 Series 1 240Z in our shop. It is a Resto-Mod car. It is almost finished, waiting on some Weber jets to finish tuning. In the process of confirming the car will pass a road inspection we discovered the rear window defroster is not working. We also found the windshield washer motor is not working, have not looked into that issue yet. Everything else works as it is suppose to.

The wiring harness and rear window defroster is from a series 1 car, the fuse box and rear window defroster switch is from a series 2 car. We have ran on ohms test on the defroster wires in the hatch, the switch and the wires from the switch to the hatch, no issues found. No blown fuse, we have power and ground to the 3 pin Molex connector, we have power at the switch. We can make the unit work, but only by manually connecting wires, then the switch is on all the time. 

What I would like to find is a wiring diagram of the rear window defroster assembly.  So far no luck. Can anybody help? 

Thanks, stay safe.

Ed 

[Zed Head]

Download the Owners Manual, it has a nice diagram on the last few pages.  Might help. 

https://www.classiczcars.com/files/category/17-owner-manuals/

Or maybe this picture will have enough detail, it's copy of the page.

 

[Terrapin Z]

My parts book lists two relays for the hatch glass. Zed Heads diagram only shows one marked as Acc Relay. Another diagram shows both. If you are mixing years it may cause problems. IMO.

Washer pumps often fail. Being a rest mod there are other aftermarket pumps that will work just don't look or fit exactly "stock"

 

[SteveJ]

The 73 wiring diagram might help more with that circuit. The defroster relay is show in it.

[7tooZ]

I must have missed something here. I think he said he has a 71 series 1??? For me that means he has a rocker switch mounted in the console behind the choke plate and it has a black color rocker. The 71 series 2??? is basically the same except the rocker color is yellow and lite. Both are wired the same. No relays. the a  switch (Series 2) has three wires B, R and GR and connects to plug with Blue (L), a RB, and a B. the L comes from the dash and has a fuse holder, RB & B go the rear hatch harness then connect to the hatch glass.  Did I miss something? Wouldn't be the first time. Here is what thinks is a Series 2 defroster switch.

If he has power to both sides of the switch in the on position and power at the glass and good ground then my guess is there is a break in the heat element.

[Terrapin Z]

I guess we will need more information from the OP. 

I always considered your switch as Series 1, and this one a series 2. 

I read the post as him having a series 1 wire harness and this Series 2 switch. (and a series 2 fuse box, short wire tails, different routings too)

But hey I could be wrong as well. Both wire diagram show the circuit goes through a relay. Defrosters should pulse on and off lest they burn up the wire filaments. 

[7tooZ]

No

Nope I don’t think you are wrong. It’s probably me. But the there is the old series1 2 3 or 4 what, when , this that etc...besides you know I only pretend to know anything about the early build date cars build between 69 and 72. They fit in my old brain.

if the pic you show of the fuse cover is a “series 2” the my moneys on you

heres my diagram above

Edit added  my Jul 71 did not have those relays but my Aug 72 might have and they are sitting in box somewhere in storage.

 

Edited April 29, 2020 by 7tooZ

[Ed Brock]

16 hours ago, 7tooZ said:

I must have missed something here. I think he said he has a 71 series 1??? For me that means he has a rocker switch mounted in the console behind the choke plate and it has a black color rocker. The 71 series 2??? is basically the same except the rocker color is yellow and lite. Both are wired the same. No relays. the a  switch (Series 2) has three wires B, R and GR and connects to plug with Blue (L), a RB, and a B. the L comes from the dash and has a fuse holder, RB & B go the rear hatch harness then connect to the hatch glass.  Did I miss something? Wouldn't be the first time. Here is what thinks is a Series 2 defroster switch.

If he has power to both sides of the switch in the on position and power at the glass and good ground then my guess is there is a break in the heat element.

No, you are correct. It is a series 1car. It has a series 2 or 3 center console. The light is yellow and lights. The color codes on the wires you discribe is exactly the colors of the wires we have on the switch and the wires from the switch.

The pictures Terrapin Z shows is what we have in the car.

Thanks for your information, the colors of the wires was very helpful. 

Ed

[Ed Brock]

23 hours ago, Terrapin Z said:

My parts book lists two relays for the hatch glass. Zed Heads diagram only shows one marked as Acc Relay. Another diagram shows both. If you are mixing years it may cause problems. IMO.

Washer pumps often fail. Being a rest mod there are other aftermarket pumps that will work just don't look or fit exactly "stock"

 

thanks for your help. question. Where are the relays for the heat glass located. I know the location of the horn relay(drives side front by kick panel) and there is a 2nd relay on the passenger side also by the kick panel. That relay(passenger side) has a 4 wire connector. I don't know what that relay goes to. It work, yu can hear it click when you turn on the ign. key.

Good maps, thanks.

Ed

[Terrapin Z]

Nissan has been elusive as to the true locations for relays and the like.  These post indicate it is on the Passenger side although the pic shows it on the Drivers side. The parts book did not indicate what years had which one. and they kind of look the same. One post below says the relay is for the blower motor and the hatch glass in one. 

Heres some old thread about # 35.    Type the numbers into google images and you will see what they both look like. 

 

 

[Ed Brock]

THANK YOU ALL. Great information. I'm a bit over whelmed with this issue. 

First off, When we started this project it was a rolling chassis. The current owner has purchased 2 other cars for parts. What I mean by a rolling chassis is it had 4 wheels, struts and brakes rotors (brakes not hooked up to the 4 wheel disc brake setup that was installed), a motor (block and head only), transmission (T5) and a rear-end (R200). The main body was a shell, absolutely nothing attached to it, or inside it. We have been working very part time on this car for 3 years now. It is almost a finished project. This car came with A/C. We deleted the  A/C.

The customer states this car is a series 1 (that issue has been confirmed, it is a series 1 car body). I believe (from schematics) and the fact that the previous owner, who disassembled the car, and had the foresight to mark all of the connection, that the main wiring harness is also a series 1. We could not use the series 1 center console (a rear defrost switch that is black in color and not lighted) because of the T5 transmission with a short throw linkage. The hole in the series 1 console would not match up AT ALL with the new trans shifter. So we installed a series 2 or 3 console (unsure which one). Still needed to build a shifter arm extension.

As this project progressed, we found we had no way of hooking up the upgrade to a Honda heater motor. In a pile of wires we found the heater motor wire connector. Some slight wire end changes and were in business (the heater motor now works). Remember, we did not hook up the A/C wiring. I mention this because it could be apart of our problem. I should mention, we used the correct color coded wiring (we had 2 wiring harness to cut up and get the correct wire colors/ends from). We also used correct colored heat shrunk on the sawdered wires. Anal, yes, but that what we do. 

Okay now, found the problem with the rear window defrost switch (bad contacts). Cleaned and the switch now works. We send power to it, we get power from green/red wire. We DON'T get power to the rear window. Checked the ground side of the rear defroster it's good. So, back to the drawing board. Hooked up a OHM meter to the red/black wire at the rear window went looking for the other end of that wire, can't find it. Removed the upgraded glove box (plastic not cardboard). Hooked OHM meter from the switch (green red then goes to a 3 pin connector that change it to blue/white) and looked for the other end of that wire. Found it, it is in a male 6 pin connector (all 6 wires are in it),  that plugs into the heater motor wiring. The female end only 5 wires coming out of it. The missing 6th wire? Well, that is the other end that connects to the rear defrost switch (confirmed it, wire is also blue/white). So hook up a jumper wire from the male 6 pin connector to the red/black wire at the rear defroster wire. Turn on switch power now at and through the rear defroster wires.

So for I have 4 questions. 1) Where did that other end of the rear defrost wire gone to (what am I missing)?  2) What type of connector is on that missing red/black wire and, is there ANYTHING between the red/black wire (rear defrost wire) that should connect to the blue/white wire (switch to turn on rear defroster)?  3) Does not hooking up the  A/C wire to the compressor have anything to do with this issue (maybe there is a different loom that we need to connect from the 6 pin connector to the heater rheostat/motor and goes to the A/C and the rear defroster wire)?  4) I am puzzled by one wire. It is on the passenger side near the kick panel, It is a factory wire, not something someone else added. It has two wires crimped together. One wire is re/back and the other wire is black. Black is ground, red/black is either power to or power from something. But both wires hooked together by the factory just does not compute with my brain cells. HELP

Thank you all again. Myself and the customer apricates your help.

Ed

[Ed Brock]

Thanks, I know what they look like I think I know where Datsun hide them. Just don't know if I should look for a 3rd one.

Thanks for help.

Ed