'73 240Z Rear Defroster

[pak52]

I'm trying to trouble shoot - anyone have a circuit diagram?

[SteveJ]

I don't have access to my 73 FSM right now. However, if you look at the link for Blue's tech tips in my signature, you can look at the wiring diagram for a 72. I'm not sure if the rear defroster circuit changed between those years.

Do you have 12volts at the terminals going to the grid?

Well, my signature didn't show. Here is the link: Blue's collection of tech tips - A great place to search for answers.

I suggest you bookmark that site.

[pak52]

No, I don't have 12v at the grid. I looked at the schem you posted a link to - couldn't find the defroster circuit ???

I moved recently and can't find my SM.

[240ZMan]

Here's a pretty good copy of a 72. Hopefully the colors didn't change in 73.

72_240z_wiring.pdf

[pak52]

I'll be darned if I can find the rear defroster circuit on that diagram...

Does any one see it?

[240ZMan]

I quickly glanced at it before I posted it and didn't see it either (figured I was just missing it), but I've used it quite a few times and it was accurate on my 73 so posted it anyway.

The 72 had a rear defroster, didn't it?

I can check my FSM later tonight.

[SteveJ]

It does have the Rear Defroster circuit on it.

Send me a PM with your email address to get a higher resolution image.

[geezer]

This one shows it.

Edit-Got outgunned by Steve...better 2 than none:laugh:

[EScanlon]

http://www.classiczcars.com/forums/showthread.php?p=157255#post157255

Use that one instead.

Credit for that old post goes go Onuthing and MDBrandy.

Ron, Steve, both of the ones you uploaded have errors in them. Steve's shows the Acc. Relay as only having 3 wires going to it, all Blue wire. Ron's does not show how the Ignition Switch receives power. It's missing the connection for the W/R wire from the fuse box.

2¢

E

[SteveJ]

http://www.classiczcars.com/forums/showthread.php?p=157255#post157255

Use that one instead.

Credit for that old post goes go Onuthing and MDBrandy.

Ron, Steve, both of the ones you uploaded have errors in them. Steve's shows the Acc. Relay as only having 3 wires going to it, all Blue wire. Ron's does not show how the Ignition Switch receives power. It's missing the connection for the W/R wire from the fuse box.

2¢

E

E, are you sure about mine having errors? It is right out of the 1973 FSM.

[geezer]

Good eye Enrique. It's common for these wiring diagrams to have several errors and omissions. Usually a FSM wiring diagram error would be caught early on by a proof reader (can you imagine a more boring job?), or a repair tech after being issued and a revision would be made, but some slip through. The people drawing the diagrams are not the same people who understand/designed the circuitry.

[EScanlon]

Yup. Take a look yourself. Right below the space between "DIAGRAM" and "(For..." in the title, you'll see a small box labeled "Acc Relay", with 3 wires connected to it. All 3 wires have "L" as their color designation. The relay takes 4 wires to complete TWO circuits...2 wires each circuit.

The balance of your wiring diagram is correct in that it shows the SECOND relay added to the 73's downstream of the FIRST Accessory Relay, and the proper wiring for the switch rocker being lighted up.

The problem with the wiring diagrams, is that it usually takes looking at 3 or 4 before you start noticing little inconsistencies. Both yours and Ron's need to be blown up real big before you start noticing subtle wiring details.

While the one that I linked to does not show the Choke Light, and the Second Relay, it will be easier to trace than the later one.

Not trying to step on toes, the wiring diagrams are just one of the more painful of the topics on the Z. Once you think you found a good one, you find an anomaly. Has anyone ever noticed that some of them make it seem as though there are TWO Blower Motors in the car?

FWIW

E