installing a tachometer

[jetmech]

Looking to finally connect a tach into my daughters bug, I purchased the deluxe harness that already has the purple wire in it that runs from the engine bay to the dash, but I'm a little unclear as to how to go about hooking it all up, the tach has a white wire for the lights witch is pretty straight forward that I would connect that to the dash light switch 58b, the black wire is labelled ground no explanation needed, but there is 2 other wires one is green labelled signal source I do believe that gets connected to the purple tach wire that then gets connected to the + side of the ignition coil or does it go somewhere else, then there is this red wire that is labelled as 12v switched power. Am I missing something?
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74' Super Beetle

[Starbucket]

The purple wire goes to the - side the and the red goes to the + side of coil.

[gt1953]

{[one is green labelled signal source]} That wire goes to the side of the coil the wire that goes to the distributor, that is the signal.
White lights
Red 12 v switched
Black ground or chassis.
Does the Tach have any instructions.
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Volkswagen: We tune what we drive.
Numbers Matching VW's are getting harder to find. Source out the most Stock vehicle and keep that way. You will be glad you did.

72 type 1
72 Squareback
({59 Euro bug, 62, 63, 67, 68, 69, 73 type ones 68 & 69 type two, 68 Ghia all sold})

[Rome]

Red wire "12 V switched" means that the tach only gets its own power for its internal circuits when the rest of the 12 V system in the car is active. So you want to connect that red wire to a local wire at the fusebox which only has 12 V after your ignition is switched on. You don't need to run another wire all the way back to the + side of the coil.

Also, make sure that your tach has a setting for 4 cylinders, or is specifically labeled as only for 4 cyl. Many aftermarket tachs are made for universal application on 4, 6 or 8 cylinder engines. The tach must have a small set of switches on the back that you set for 4 cylinders; or separate terminals.

[jetmech]

gt1953 So I am correct in that the green signal wire will connect to the purple wire that will go to the engine bay and connect to the + side of the coil, And under the dash I would connect a switched 12V wire to the red wire, as for the white it will connect to 58b on my headlight switch and the black wire will go to ground.

Rome this tach does have a switch for setting it to either 4, 6, or 8 cylinders so I will make sure it is set to 4.

Thanks for the help.
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74' Super Beetle

[Cusser]

[ashman40]

This diagram should help some:

The black ground wire does not need to go all the way back to the battery. You can ground the tach anywhere in the truck to a good chassis ground.


As others have pointed out above... the signal wire from the tach runs to the (-) terminal of the ignition coil. On VW coils this is labeled #1. The same terminal the distributor points wire (green or black) connects to. This is because the "signal" comes from the distributor points opening and closing.
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AshMan40
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'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}

[jetmech]

Thank You for the correction Ashman and Cusser.
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74' Super Beetle