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Question for the EE people

 
Old 10-26-2018, 10:33 AM
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I bought one of these to switch my headlights:

Rotary Switch

The system I have wired has the OEM light relays. I switched the ground side of the relays.

I would like position 1 to be parking lights. Position 2 should be parking lights + headlights. And position 3 should be parking lights + high beams.

Is there a way to wire this using this switch? Previously I have wired each function to a separate switch. It seems like I should be able to using a some sort of diode or gate... but I can't remember my EE stuff from that class I had to take 20 years ago.

Thanks
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Old 10-26-2018, 02:02 PM
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NA or NB? Both use the combo switch itself (not a relay) to switch between lo/hi, but the NA switches the +12 side of the filament, while the NB switches the ground side. The NA also has the added complexity of the retractors.

I found the closest P/N on that switch (who knows with random china junk), and it appears to have multiple poles. The part number listed in the details on UX (SZW26-20) is for a switch with no "off," so I'm assuming the one you actually bought is the same but with an "off" position. Good news: it has multiple poles!



Assuming NB, since you didn't mention retractors:
TNS relay coil ground connects to terminals 1,5,9
Headlamp relay coil ground connects to terminals 1,5,9
Low beam filament ground connects to terminal 7
High beam filament ground connects to terminal 11
Under-dash ground point connects to terminals 2,4,6,8,10,12

This will work with no diodes. The only non-OEM behavior is that the headlight relay will be switched on in the parking light position, but no current will flow through it. If you do not have fog lamps, this will not have any observable effect. You should also make sure it goes to a beefy ground point, as it will be carrying ~10A of current (just like OEM).

You will need diodes to make it work in an NA with retractors. NA with no retractors and aftermarket headlamp conversion can be done with no diodes.
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Old 10-26-2018, 02:10 PM
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Is this for a track car?
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Old 10-26-2018, 04:04 PM
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Street car, but I build race cars and this one has the stuff on the column relocated to the dash.

The car is NA, Jetstream headlights. No pop up motors. NB wiring harness. Lots of custom work in the harness. Three relays, ground switched. Any way I see it, with this switch, all the lights come on at any switch on position. Position 0 is all off.
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Old 10-26-2018, 04:49 PM
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Originally Posted by Satisaii View Post
No pop up motors. NB wiring harness. Lots of custom work in the harness. Three relays, ground switched. Any way I see it, with this switch, all the lights come on at any switch on position. Position 0 is all off.
There are no listed specs for that switch and what the different poles do in different positions. It is impossible for anyone to answer your question with 100% certainty without that info.

Based the image that I posted (which is from googling the part number), it is a six-pole switch, which make sense given the number of terminals. If that is true, it should be very easy to get your setup working exactly as you want with no rewiring and no extra components. But you need to figure out the correct connectivity of the terminals in each position if it's not consistent with the picture above.

I can tell you just by looking at its construction that it does not just connect one input to one of three different outputs. It has a more complicated table that will be similar to the one I posted above, if not the same.
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