1974 Datsun 620 clock install?

[74datsun620]

Is installing a clock in a 1974 Datsun 620 pickup a plug in deal? I just bought a 620 clock and have both sides of the plug sow does my 620 have a plug for it behind the dash or do I need add the plug to my wiring harness?

[datzenmike]

My info shows a clock on the '73s as well. There should be a plug for constant power with key off and one for the dash lights.Looks like a single Blue/White stripe wire for the power. (it is on the room lamp/cigar lighter circuit) The lights are two wires, one will be Green/Blue I think.

 

You could wire the lights on all the time with the key but the clock needs constant power.

[74datsun620]

Thank you Mike!

[wildmaninid]

The harness for that should be taped up under the dash to the main harness. That looks like exactly the same harness for a tachometer. If you look at the hole where the clock goes, and look way up above where the harness runs, you will see the pigtail for it up there, usually wrapped up to the main harness with blue electrical tape. Find that, should plug right in no worries!

 

 

Bill

[datzenmike]

Bill, the six wire plug for tach or clock wasn't used until '76 when the tach became an option I believe. That does look like the plug but may have come with the tach. (could be wrong)

[wildmaninid]

I put a tach in my 75 and the wiring was already there?? I was under the impression all 620's had it.......I have been wrong before and could be wrong on this also..........but it isn't hard to check and see if it is there if you know where to look! At least a clock is a pretty basic electrical install.

 

 

Alright

 

Bill

[datsunaholic]

73-75 had wiring for a clock, but not the tach. '76-on had wiring for both. However the plug changed radiacally since the tach/clock plug on a 76-79 has more wires.

[74datsun620]

[H-BRATSON]

I know this question may be dumb as I have the schematic in my hand for the full wiring harness, but what are the yellow and green wires going to. trying to rebuild this circuit due to previous owner. Thanks in advance.

 

[datzenmike]

None of the 620 tachs had a green or a yellow wire. They appear to be twinned together like speaker wire and Nissan didn't do this. It's a poor blurry picture so maybe an owner added these.

 

For a '77 the tach/clock plug in the dash harness was ...

 

Black................... Ground

Blue/White......... Power as mentioned before connects also to the lighter. On all times for the clock, not needed for tach

Blue.................... Signal from the negative terminal on the coil

Red/Black +

Red/Blue............ Power for the illumination to light it up. Polarity doesn't matter

Black/Green...... Power from fuse box, 15 amp, ignition switched.

[H-BRATSON]

6 hours ago, datzenmike said:

None of the 620 tachs had a green or a yellow wire. They appear to be twinned together like speaker wire and Nissan didn't do this. It's a poor blurry picture so maybe an owner added these.

 

For a '77 the tach/clock plug in the dash harness was ...

 

Black................... Ground

Blue/White......... Power as mentioned before connects also to the lighter. On all times for the clock, not needed for tach

Blue.................... Signal from the negative terminal on the coil

Red/Black +

Red/Blue............ Power for the illumination to light it up. Polarity doesn't matter

Black/Green...... Power from fuse box, 15 amp, ignition switched.

Mike thanks again man! I’m going to have to build the clock harness from scratch! Any pointers?

[Ooph!]

That clock looks as if it came out of something newer and has previous owner mods.

Get yourself a copy of the factory service manual, this thread has links:

Page BE30 gives info on connecting the clock to the instrument cluster and harness and the wiring diagram gives a little info.

The attached picture of a gage cluster should be similar and shows about where the connections are.

 

 

 

 

[H-BRATSON]

5 hours ago, Ooph! said:

That clock looks as if it came out of something newer and has previous owner mods.

Get yourself a copy of the factory service manual, this thread has links:

Page BE30 gives info on connecting the clock to the instrument cluster and harness and the wiring diagram gives a little info.

The attached picture of a gage cluster should be similar and shows about where the connections are.

 

 

 

 

I checked the back of the cluster for spades and there are none:/ so I’m assuming I’ll have to run it the way Mike said.

[datzenmike]

The '78 will have a tach plug over on the left side above behind where the tach is installed. I got a tach and added wires for it only to remove the cluster to install and find the plug already there and waiting. 

 

There are two styles of tach. Direct with a wire from the coil negative side and induction with the tach in line between the distributor and the coil negative side. A '78 would be direct but you may have an inductive. Can you post a picture of what you have???

 

This is an inductive style. See the Black/White stripe wire that makes a loop? One end goes to the distributor, the other goes to the coil negative terminal. The tach 'senses' the signal flowing through the wire.

 

 

If yours doesn't have the loop then you have the correct tach for the '77 although you can make the other style work.

[Ooph!]

3 hours ago, datzenmike said:

The '78 will have a tach plug over on the left side above behind where the tach is installed. I got a tach and added wires for it only to remove the cluster to install and find the plug already there and waiting. 

 

There are two styles of tach. Direct with a wire from the coil negative side and induction with the tach in line between the distributor and the coil negative side. A '78 would be direct but you may have an inductive. Can you post a picture of what you have???

 

This is an inductive style. See the Black/White stripe wire that makes a loop? One end goes to the distributor, the other goes to the coil negative terminal. The tach 'senses' the signal flowing through the wire.

 

 

If yours doesn't have the loop then you have the correct tach for the '77 although you can make the other style work.

 

I guess I'm confused, he said in the title its a 74 and the picture he posted is a clock is he installing a clock or a tach in a 74 or 78? or both

[datzenmike]

The picture is in a necro post from 2010.

[Ooph!]

1 hour ago, datzenmike said:

The picture is in a necro post from 2010.

 

uhggg that'll teach me

[MikeRL411]

7 hours ago, datzenmike said:

 

 

7 hours ago, datzenmike said:

 

 

7 hours ago, datzenmike said:

There are two styles of tach. Direct with a wire from the coil negative side and induction with the tach in line between the distributor and the coil negative side. A '78 would be direct but you may have an inductive. Can you post a picture of what you have???

 

 

 

 

 

Forgive the multiple deletes.

There is a third type of tach, the purely mechanical one.  The early roadsters had an offset worm gear on the distributor shaft and a speedometer cable and movement calibrated in RPM.  True engine rotations.

[datzenmike]

But as far as the 620 tach install there were only two style. The Roadster cable drive is not a viable option even if you had one.