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I'm trying to replacing a broken switch in my 1986 Corvette. It's in the door panel which can be pressed to turn the door panel interior light on and off. The switch itself has only the manufacturer marking and no part number (mfg: Judco). Looking at Digi-key I believe I've found the switch, at least, the dimensions match:

https://www.digikey.com/en/products/detail/judco-manufacturing-inc/40-3658-01/611173

I want to make sure the switch behaves the same, but I don't understand the functional description in the data sheet:

enter image description here

Please help me understand what "ON A - ON A&B - ON B OFF" means so I can test the switch in the other door, which is functional, to make sure this is the same part.

Also, how can something be a "4 way" switch as stated in the description with only 3 wires?

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  • \$\begingroup\$ I think it is a typo. I assume 3 states: 1->A-C, 2->A-B-C, 3->B-C. If that is correct A-C could be used as light switch. \$\endgroup\$
    – Jens
    Commented Jul 1 at 14:46
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    \$\begingroup\$ Is this what you need? corvettecentral.com/c4-84-96/interior-trim/… \$\endgroup\$
    – GodJihyo
    Commented Jul 1 at 17:10
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    \$\begingroup\$ Frankly, the auto maker was a big enough customer that the part can be entirely custom. If you want to guarantee the right switch, you should work hard to find the part through auto parts suppliers. \$\endgroup\$
    – Scott Seidman
    Commented Jul 2 at 18:56

2 Answers 2

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C is common. The switch has four states:

  1. A connected to C
  2. A,B both connected to C
  3. B connected to C
  4. C open

There is a typo in the datasheet, it should read 4 WAY (ON A - ON A&B - ON B - OFF), or, better instead of using hyphens, just use commas like most people would expect: 4 WAY (ON A, ON A&B, ON B, OFF).

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  • \$\begingroup\$ That makes much more sense, thank you! \$\endgroup\$
    – LarryBud
    Commented Jul 1 at 16:35
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    \$\begingroup\$ commas, semicolons, slashes, even a typwriter arrow ->; all would be better than hyphens/dashes. It's like they chose the worst punctuation they could find the would just about do, then got that wrong \$\endgroup\$
    – Chris H
    Commented Jul 2 at 8:28
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It's called a 4-way switch because it has four possible positions, and it connects the wires in each of four different ways.

Press once, and circuit A is energized. Press again, and now A and B are both energized. On the third press, A is de-energized but B stays on. On the final press, both are off. So: "On-A". "On-A&B", "On-B", "OFF".

C, by happy coincidence, is the Common lead.

It sounds as though your application only switches one light circuit, so this isn't an exact match. If you installed it, you would find that you had to press it twice each time you wanted to switch the lights on or off.

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  • \$\begingroup\$ Thank you! I would have to look at the wiring diagram, but there are two door panels, two switches, and two lights. I believe when you turn on one side, both sides go on. \$\endgroup\$
    – LarryBud
    Commented Jul 1 at 16:36
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    \$\begingroup\$ @LarryBud It's likely you need a switch which will alternate between A and B. With one such switch on each end of two wires A and B, the circuit will be closed when they are both A or both B, and open when they are in different positions, so any change of either switch will switch from on to off or off to on. This seems to be ref 40-4169-00 in that series. \$\endgroup\$
    – jcaron
    Commented Jul 2 at 14:02

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