620 clock install question

[Rubberman]

On my 620, I know the wire hookup for the factory tach is on the wiring harness, I would take it that it also is for the factory clock hookup? Right? The plug is the same and figured they have it wired for both, seeing how they're in the same spot. Now, I know that after upgrading to a electric dizzy that you can't use the factory hook up for the tach. So would that mean the clock would have to be hard wired also? Anyone know? Probably don't have anyone with this problem, because everyone is putting factory tachs in, not clocks.

[datsunaholic]

Neither assumption regarding the EI upgrade is true.

 

The clock simply gets power from the plug for running the clock (always hot, same fuse as the cigarette lighter and dome light) and running the illumination. As long as those wires still work (and there's no reason they wouldn't unless someone hacked the harness or the fuse keeps blowing) then the clock will work fine. The clock doesn't use the ignition-only wire nor the coil trigger wire in the plug.

 

The Tach uses the same illumination wires, ignores the always-hot, and uses switched ignition for power. To DRIVE the tach, it's using the wire that comes off the negative post of the coil. If you COMPLETELY change the wiring between the coil and distributor, then yep it won't work. BUT if you leave the factory coil (-) wire hooked up, the tach will still work, even if you add a new wire between the coil and EI unit.

[yello620]

The factory tach is wired into the same plug as the tach. And it should work fine with the electronic dizzy. The clock is only using three of the wires in that plug i think. It is using the constant battery hot wire to run the clock. And the parking light wire for night time. Both could be tested with a test light.:D The third wire is the ground wire. Ground is black wire.

 

The other wires are for the tach.

[Rubberman]

Thanks fellas, that helped. I guess I've either got a wiring problem or the clock doesn't work. I'm gonna check the clock first and then go from there.

[Rubberman]

Well, I'm not getting any power to the instrument lights, this is gonna suck.

[datzenmike]

Probably blew the fuse.

[Rubberman]

Fuses are good to go, that obviously was the first thing I checked. Bonvo mentioned the reostat on my build thread. Where's that sucker at? The reostat, not Bonvo.

[datsunaholic]

The rheostat is the little twisty knob on the dash to the right of the steering column... the one that makes the way-too-dim dash lights even dimmer. If it's missing that would explain why there aren't any dash lights...

[stevensonDNL]

On my '77 620 KC I know that there is an in-harness glass cartridge fuseholder/ fuse on the passenger side of the cab interior just below the windshield wiper motor behind the glove box. You can see it if you look above the package tray that's below the glove box. It's right where the harness comes through the firewall from the engine compartment. I don't remember the wire color, but I believe the dome light, cigarette lighter and clock power passes through that fuse. Instrument illumination also? No wonder my rheostat doesn't work! I've got that fuse removed.

 

Dan