rear defroster

[nh'sown ck]

Can someone tell me the physical path of the wiring for the rear window defroster on my 78 280Z. I recently purchased this Z for my wife and the recent cooler weather led me to find that the wiring isn't even making it to the connectors on the glass and would like to have an idea as to where the wiring is suppose to be. Any assistance would be greatly appreciated.

[SteveJ]

Here's a link to the manual: 

 

Go to the BE section and start on page 70.

[nh'sown ck]

On 10/31/2017 at 10:30 PM, SteveJ said:

Here's a link to the manual: 

 

Go to the BE section and start on page 70.

Thanks for the manual download, it 's more complete than anything l have seen to date. I would like to know where inside the car the wiring harness to the rear defroster runs before l start taking things apart to search.

[SteveJ]

I posit that you are taking the wrong approach. Troubleshooting would be much easier if you first looked at what could fail.

There are four switches that control the circuit and two fuses. Look at these first.

1. Ignition switch

2. Ignition relay (passenger kick panel)

3. Defogger switch

4. Defogger relay (passenger kick panel)

Divide and conquer. Take the fuses out and check them for continuity. Turn on the ignition. If the defogger switch lights up, you know the circuit is good up to the defogger relay. If the switch doesn't light up, check for voltage to ground at the blue wire. If it doesn't, you probably have an issue with the ignition relay. However, if other accessories work fine (such as the fan), you can eliminate the accessory relay.

If all of that checks out, move to the defogger relay. Check voltage to ground at the blue/white wire and red/white wire. Also make sure there isn't corrosion on the relay body that is insulating it from ground. Have someone operate the defogger switch while you listen closely to the relay. It should click when the switch is operated. If you don't here any clicking, the relay is probably bad. 

From that relay, the wiring goes along the right side of the car to the back (BE-2). The circuit is grounded in the hatch area.

[nh'sown ck]

Thanx, I guess l didn't let you know that the wiring is not making it to the connectors on the rear windshield. The car has been wired for a sub woofer amp, which i am removing, and this may have something to do w/ the missing wiring but knowing where it is supposed the be gives me a starting point. Thanx again.

[SteveJ]

Okay. This may help you, too. http://www.carpartsmanual.com/datsun/Z-1969-1978/electrical/wiring/dash-body-(from-aug-76)