bjhines

All I can say is.... WOW!... what a nice job they did.. It lasted this long and was just beginning to have a few lighting issues....Dome, Headlight, parking etc.

I have stripped all of the electrical wiring... My intention is to improve.. but not to remove circuits... some of the extras will be beneficial...

I have done most of the sorting... I still have a lot of work to do.
To be honest... I have not actually planned this completely... so far this has been more of a fact finding mission.

FACTS:
chassis built 2/73 240Z California reg: EGR, AIR CON, etc.

I always wondered about a few weird things about this crossover 240/260Z electrical system.

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Fuel pump:

Well... It follows 260Z standards.. It has a lot of extra wiring that serves to operate the fuel pump to prime the system and then shut off once the engine is running... Mechanical pump takes over from there... It has 2 cut out relays, several connectors(in 3 harnesses) and an inline fuse... It comes out neatly and leaves a connector that has IGNITION SWITCH (not fused)power and a green wire to the rear 14guage.

It originally worked by operating the pump when the ignition is switched on... then the start key position would kick off a relay to cut the pump... then when the key was returned to the IGNITION position it would switch the pump back on... until the alternator came up to voltage and kicked off a second relay to cut power to the fuel pump....It was originally fused(15A) inline near the connector behind the heater console.
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AIR CON:

I saw lots of extra wires... in weird places... This sucker is wired for dealer installed AIR CONDITIONING. not much mind you.. but there are several unused climate control wires and connectors in my non AC version. They all get power through a relay and 2 fuses.
Kind of redundant without AC... They have a 20A fuse panel circuit that runs a relay that operates the blower motor fed by BATT+/ammeter power. The blower relay circuit has an INLINE 20A fuse(blue wires).

They are using a 20A fuse to kick a 0.2A draw relay that uses a 20A inline fuse off BATT+... the only thing the fuse in the fuse panel would operate would be the blower relay and the compressor clutch... in my car it takes only 0.2A to kick the relay... soo there is a useful circuit that cant be blown out by the blower... it is almost unused and isolated...

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Dome lights:

has anyone ever seen the kick panel courtesy lights in the diagrams???... The connectors are indeed there(on each kick panel near the door pin swich connectors)... I would imagine they are something similar the the glove box light without the switch...

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FOG LIGHTS:

There is a single RED 14G wire that runs to the front harness and splits to both sides where the headlight/turn connectors are.
There is an unused connector behind the heater control panel that recieves power through the ACCESSORY relay circuit(I cant remember if it is fused)... there are common grounds near the front clip connectors as well.

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ANTI THEFT:

This brings elaborate things to mind....

In reality it is a switch in the ignition key cylinder that operates the buzzer if the door is opened with the key in the ignition (regardless of key switch position).

The same buzzer is tied into the seat belts, the passenger seat bottom, and the neutral switch on the manual transmission...
This serves to operate the buzzer if the driver or passenger does not have their seat belts on when the ignition is ON and the transmission is shifted out of neutral(into any gear)...

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WIPER DELAY/WASHER INTERMITTANT:

The damn wipers are COMPLICATED!!!! most early Z cars diagrams dont show this in detail... but there are only 2 speeds for the wipers: slow and fast.... ahh... but there are 3 positions on the wiper switch: slow, medium, fast....
The slow setting uses an intermittant relay on the passenger kick panel.... This relay also operates the wipers if the washer button is depressed... 10 extra wires running back and forth with a big relay in the way... and these wires get you: not fast enough, still too slow, and almost fast enough.... LOL!

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EGR CIRCUIT:

There is a relay on the firewall right above the heater hoses... this is an EGR relay.... this took some creative thought... I have never seen the early system in operation... but I did figure it out...

The relay operates a vacuum soleniod that deactivates the EGR valve until the car warms up....
There are several components in the system... A green wire that operates the solenoid, a thermostat housing temp switch, an interior kick panel thermal snap switch(opens above 32*F), and a firewall mounted relay.

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I plan to add dual radiator fan relays, Headlight relays, FOG light relays, and an ignition system relay, one extra relay circuit will be added for future expansion.

The harness has an amazing number of crimped splices all over the place... I counted 16 splices in the engine bay harness alone.... I am soldering all of them...

I will also be converting some of the original circuits to operate new devices and guages.