g-mam Posted July 18, 2009 Report Share Posted July 18, 2009 Trying to figure out how to wire this tach into my 620. Goes to Ground Goes to + 12v when ignition is on Goes to dash lights Goes to Neg. Coil side NO CLUE ! :confused: Quote Link to comment
RatRod25 Posted July 18, 2009 Report Share Posted July 18, 2009 #5 looks like its just a looped wire?? :confused: Looks like it doesnt connect to tach at all.. Quote Link to comment
datsunaholic Posted July 18, 2009 Report Share Posted July 18, 2009 That's an induction tach. The wire from the points to the (-) coil post has to go through that loop. That particular tach is wired in series with the coil. Otherwords, the stock points-to-coil wire is disconnected, and the tach takes the place (with longer wires of course). #5 goes to the dist, #4 goes to the coil, though it doesn't really matter which direction since it's inductive. Quote Link to comment
moparvwfreak Posted July 18, 2009 Report Share Posted July 18, 2009 cool! now i know how to wire in my tach int o my 73, once it runs again. Quote Link to comment
g-mam Posted July 18, 2009 Author Report Share Posted July 18, 2009 That's an induction tach. The wire from the points to the (-) coil post has to go through that loop. That particular tach is wired in series with the coil. Otherwords, the stock points-to-coil wire is disconnected, and the tach takes the place (with longer wires of course). #5 goes to the dist, #4 goes to the coil, though it doesn't really matter which direction since it's inductive. I wonder if this will still work with my Igniter sytem? I eliminated the points? It still has a wire to the - side of the coil. Quote Link to comment
moparvwfreak Posted July 18, 2009 Report Share Posted July 18, 2009 i dont see why not. just run the tach in series with the neg side. Quote Link to comment
g-mam Posted July 19, 2009 Author Report Share Posted July 19, 2009 Do you think there is wiring already there in the dash of the '74 for the tach, or maybe a clock? Quote Link to comment
ggzilla Posted July 19, 2009 Report Share Posted July 19, 2009 It uses induction wiring, the coil + wire feeds that loop. All the Datsun 1200 tachometers are wired like that. The 620 tachometer I have (otherwise look like a 1200 tach) is conventional wiring, no loop. Instead you connect it to coil -. Or electronic ignition Blue wire. Quote Link to comment
datsunaholic Posted July 19, 2009 Report Share Posted July 19, 2009 (edited) They didn't have wiring in the dash for a tach until '76 (maybe '75), when the factory option/dealer option tachs became a plug-in deal, elimitanting the wire loop. The plug-in tachs wired in parallel. Quite different externally. Dave, you sure it's the coil (+) wire? That's simply drop-resistored 12V hot off the ignition. Though I suspect it doesn't matter as the current through both is the same. Edited July 19, 2009 by datsunaholic Quote Link to comment
g-mam Posted July 20, 2009 Author Report Share Posted July 20, 2009 I jury rigged the tach today to test and it works fine. Now, can SOMEONE TELL ME HOW TO REMOVE THE INSTRUMENT PANEL :confused: I have removed the three screws in each housing, and I found one under the dash, but the right side is just solid. I unscrewed the Wiper control (and can't figure out how to get that knob off). I removed the heater knobs. The radio is free, I just can't figure it out. Removed the ashtray mount, nothing there. It seems solid near the dimmer for the dash lights. I looked under the dash for an hour, pulling on it trying to figure out how to get it out. There must be a secret somewhere. Quote Link to comment
Suspect Posted July 20, 2009 Report Share Posted July 20, 2009 (edited) The wiper switch and the cigarette lighter hold in the right side. The wiper knob pulls out but its attached to a fiberoptic. The fiberoptic has to be unhooked, I had to cut mine near the box that lights it. Edited July 20, 2009 by Suspect Quote Link to comment
g-mam Posted July 20, 2009 Author Report Share Posted July 20, 2009 I have the wiper nut loose (still can't get the knob off). How is the Cig lighter holding it in? I can't see it, will have to use the braille method. Quote Link to comment
420n620 Posted July 20, 2009 Report Share Posted July 20, 2009 (edited) take needle nose plyers to hold the shaft for the wiper then push knob in and turn. Cig lighter has a hollow barrell shape on the back side and unscrews, remove the wire first then put a finger inside where lighter goes to hold it in place as you unscrew the barrell. gl Edited October 19, 2011 by 420n620 info added Quote Link to comment
g-mam Posted July 20, 2009 Author Report Share Posted July 20, 2009 I'll give it another go tomorrow. Thanks. Quote Link to comment
g-mam Posted July 22, 2009 Author Report Share Posted July 22, 2009 The Cig lighter was the trick. Got the pod out and mounted the tach. Will wire it later, just wanted to make sure it fit. Quote Link to comment
420n620 Posted July 22, 2009 Report Share Posted July 22, 2009 good to hear Gary, I got to do the same thing ---- some day, maybe I'll just take the complete dash out... Quote Link to comment
Braden Posted July 22, 2009 Report Share Posted July 22, 2009 i saw the pic of the back of the tach just curious as to what the front looks like or what kind it is, i would really like to put one in my truck, thanks Quote Link to comment
g-mam Posted July 22, 2009 Author Report Share Posted July 22, 2009 Here's Jester's photo, from whom I purchased it. I polished the lens up nice and clear. Quote Link to comment
pharouh Posted June 15, 2011 Report Share Posted June 15, 2011 I know this is an ancient thread,but I'm installing a tach in my 73 620 ,and my tach is different. I'm not sure if it's a 1200 or what. If I'm reading this right the black/white wire on the left (maybe blue/white?)goes to the coil - side? Quote Link to comment
ggzilla Posted June 15, 2011 Report Share Posted June 15, 2011 How you wire it Depends. Do you have that same Tachometer or one with different wiring? ONE without a loop wire? you connect the B/W wire to coil - (coil neg) OR ONE with a loop wire? The wire loop goes into the coil circuit. * What Datsun did was splice the loop into the dash harness coil feed wire. * or you could remove the wire from the Ballast Resistor, reroute it into the cabin and connect it to one end of the loop (#4 in the photo). Then run the other end of the loop (#5) back to the resistor. As DH said you could probably do same for COIL NEG wire (maybe easier as it doesn't matter about the resistor/lack of resistor) but the factory wiring was on the COIL POS side. NOTE: If you have converted to EI and removed the Ballast Resistor, do it for Coil + wire. Quote Link to comment
pharouh Posted June 15, 2011 Report Share Posted June 15, 2011 The one in my post is the one I have. I bought it that way. The guy just cut the wires. I'll try the - coil wire then. Thanks Quote Link to comment
ggzilla Posted June 15, 2011 Report Share Posted June 15, 2011 OK, your is a regular 620 tachometer: This is wired is just like a typical aftermarket tachometer only three wires are required. * BLACK wire: ground, can connect it to the metal dash frame * YELLOW/red wire: 12V, wire to IGN + somewhere under the dash * BLACK/white wire: connect to COIL NEG post The lamps don't need to be connected for the tach to work. But usually they are connected to some BLUE wire under the dash. 1 Quote Link to comment
pharouh Posted June 15, 2011 Report Share Posted June 15, 2011 Great! I'm redoing the dash right now,and have the harness out. Thanks for the help! Quote Link to comment
jefe de jefes Posted June 15, 2011 Report Share Posted June 15, 2011 ^^^^^ gg has it right. Quote Link to comment
SUD620 Posted October 19, 2011 Report Share Posted October 19, 2011 How you wire it Depends. Do you have that same Tachometer or one with different wiring? ONE without a loop wire? you connect the B/W wire to coil - (coil neg) OR ONE with a loop wire? The wire loop goes into the coil circuit. * What Datsun did was splice the loop into the dash harness coil feed wire. * or you could remove the wire from the Ballast Resistor, reroute it into the cabin and connect it to one end of the loop (#4 in the photo). Then run the other end of the loop (#5) back to the resistor. As DH said you could probably do same for COIL NEG wire (maybe easier as it doesn't matter about the resistor/lack of resistor) but the factory wiring was on the COIL POS side. NOTE: If you have converted to EI and removed the Ballast Resistor, do it for Coil + wire. Hey You can Drawing for Loop wire Feature Thank you evrry much Quote Link to comment
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