Sanity check my gauge wiring plan

[virusdoc]

I'm installing three VDO gauges (tach, oil temp, oil pressure) in my 76 convertible. They will be mounted on the speedo cowl, with wiring harnesses passed through the dash metal (in grommets of course). Sensor wires I have run from the engine compartment under the carpet.

I need a source of ignition switched 12V and light switched 12V for the gauge power and backlights, respectively. And a good ground.

My plan is to tap into the back of the headlight switch for the 12V+.

Specifically:

Tap into X for ignition switched 12V (my switch does use this terminal). Total current for all three gauges should be less than 0.5 amp.

Tap into 58b for light switched 12V. Total current for all three backlights should be less than 1 amp.
(I'll solder and shrink wrap all taps.)

For ground I'll sand a spot on the firewall and put a machine screw through the sheet metal.

Does this sound reasonable? Thanks for your time!
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1976 Convertible Super Beetle, "June Bug".
FI-->34PICT3 carb conversion-->now dual 40 IDFs
Self-rebuilt 1904 (after totally botching a 1641 rebuild, cussing a lot, and throwing lots of cash in the fire)

[Cusser]

I've had those 3 gauges in my own VW for over 4 decades.

I tapped into the fuse box for 12 positive switched power and the cluster illumination for their light circuit.

Ground is any screw or bolt that goes into body metal.
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1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297

[virusdoc]

My plan worked fine. All gauges operational. Thanks for the reply, Cusser.
_________________
1976 Convertible Super Beetle, "June Bug".
FI-->34PICT3 carb conversion-->now dual 40 IDFs
Self-rebuilt 1904 (after totally botching a 1641 rebuild, cussing a lot, and throwing lots of cash in the fire)

[ashman40]

Just a note... the "X" wire at the headlight switch is NOT fused. The black/yellow "X" wire that runs to the headlight switch does come from the fuse box, but it comes from the unprotected side of fuse #10. You can prove this by removing the #10 fuse (simulating a blown fuse). Your gauges will still be powered.
This means you need to add an inline fuse to protect your three gauges.

Alternatively, tap your power from the OUTPUT side of fuse #10 where your wipers tap power from. This side of the fuse is protected. The additional load of the gauges should not be a problem.


Just be aware that by using the "X" circuit... your gauges will be powered when you initially turn the gauge to ON/RUN. When you rotate the key to START your gauges will loose power from the "X" circuit. The entire "X" circuit is not powered while the starter is cranking the engine. When the key is rotated back to ON/RUN the gauges will have power once more.
If you want to see your tach and oil pressure gauge readings WHILE you are cranking you should switch from the "X" circuit to the #15 circuit (fuses #11 & #12) which ARE powered while the key is in the START position.
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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!}

[Cusser]

[ashman40]