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I'm trouble shooting an inoperable leveling system. So far I've replaced the toggle switch, replaced one of the solenoids, rebuilt the motor and installed a solid state control unit. None of that solved the inoperability.
When I looked at the brake light switch I found it connected not per the wiring diagram in the Service Manual (purple wire on the center contact). When I wire it per the diagram, the brake lights are on, until I press the brake pedal, and then they go off. Can anyone verify that the purple wire is supposed to be on the center terminal? Thanks.

It was probably correct with the purple wire on one outside terminal. I don't remember which but the main wiring diagram shows the purple wire going on one of the outside terminals. I think the small diagram that is showing only the TL circuit is in error. Unless someone comes along that remembers or has a car to look at and can post the information you can figure it out with a little experimentation.

Remove the wires from the switch and only connect the purple wire. Try it where it was originally. With the brakes off one of the other terminals should also have voltage. Remember that one and then press the brakes. The one that had voltage before should now be off and the remaining terminal should be energized. If it doesn't work that way move the purple wire to the other outside terminal and repeat the process.

When you have it figured out, put the light green wire on the terminal that has voltage with brakes relaxed and the dark green wire on the remaining terminal that is energized when brakes are applied.

Thanks for the procedure. I didn't get all the way through it, but here's what I found. If I put the center post at 12 o'clock, the two side posts are at 3 and 9.

When I put the purple wire at 9, I measured 12.3v at 12, and 8.4v at 3. Also, with only purple at 3 the brake lights were on.

When I put the purple wire at 3, I measured 8.8v at 9, and 6.8v at 12. Brake lights were off.

With voltage at all three posts without the brakes being applied I conclude the switch is defective. Is that correct?

There should only be one terminal active at a time. If you are reading actual volts on both terminals and not just a few floating millivolts on the second the switch is suspect.

Interestingly, if there is actual voltage on both terminals enough to light the brake lites that should not be the cause of your problem. The purpose of the 3rd terminal is to disconnect the TL when brakes are applied so it doesn't try to level in a non standard condition as might be caused if the nose was down slightly after brake application. Perhaps the less than 12v on each terminal is enough to make the control switch inoperative.

You can completely rule out the brake switch as the TL issue by temporarily connecting purple and light green together with a jumper wire. That should put 12v volts at the under dash switch and if that is on also at the center terminal of the control switch. One other thing to check is polarity. I don't know if yours is one of the solid state switches that are polarity sensitive but make sure yours is correct. If it works with the jumper then the brake switch needs replacing. If not, more troubleshooting.

I was able to rig up enough air pressure to test a switch. Common and only one other terminal has the battery voltage at a time. The non active terminal was floating around in the 10-25 millivolt range when the other was on.

If yours is a factory switch with the 3 round bullet terminals the common terminal is at 9. N.C. terminal is 12 and the N.O. terminal is 3. That would make the purple wire at 9, light green at 12 and dark green at 3.

If yours is the old VW type switch with flat tab terminals that some tried for replacements I don't know if those are the same. Those switches also had problems and several said they didn't last nearly as long as the factory switches. There is some question if VW may have used different type switches on some models and could have used a switch with different operation.

With the high price and limited availability of NOS original switches, if you need a new one I would strongly consider using one of the kits where the 3 terminal switch is replaced by a commonly available 2 terminal switch and relay circuit. The two terminal switches are available everywhere for almost no dollars and the kits are sold by several regions and vendors. If you have the desire you could also make your own relay adapter for a few dollars. A completely mechanical switch clamped to the steering column and operated by the pedal arm is also an option several of us have implemented.

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We're making progress. I was able to locate the spare three post switch I bought years ago. Installed it and connected the purple wire at 9 o'clock and the brake lights didn't illuminate. Good sign. Hooked light green and dark green as you suggested. Still no brake lights. Pushed the brake pedal and have brake lights. All good. Turned the T/L toggle switch on and nothing happened. Grounded the side terminal of the 'up' solenoid and heard the motor start (first time that's happened) but the back end didn't come up. Left the motor run and slowly the rear started to come up. Car now sits level--another first. Looks a lot better than the butt sitting on the ground. Major progress, now need to figure out how to make it level automatically.

And the small T/L diagram on page 63 (Figure 96) is incorrect.
Making the center post 12 o'clock:
* 9 o'clock is purple
* 12 o'clock is light green
* 3 o'clock is dark green.

Thanks for your help.

If own a 1956 model with pushbutton transmission control, check the relay that prevents engagement of the transmission in reverse while moving forward. It is a small aluminum can that bears a resemblance to a toy top mounted horizontally under the car inside the frame rail on the driver's side near the transmission. Good luck.

Good to hear the brake switch solved part of the problem. I would next verify you have the 12v on the lt grn wire at the control switch. You can also ground the pink or yellow wire while you are down there to verify the limit switches and wiring to solenoids are OK. If the compensator is somewhere in the middle and not at a limit switch position you should be able to bring in each solenoid from the control switch.

Don't know if you are on a 55 or 56 or if you have the complete schematic of the entire system. If not, here it is for both years. Note that the 56 schematic has the optional factory manual up/dn over ride switch drawn in. For those with a 56 without that switch, the lt grn wire will be solid from the brake switch to the under dash switch. Obviously the control switch is the old bimetal heaters and will be different from your new SS conversion.

I don't have any info on the solid state switches to know exactly what was changed internally. Suspect the bimetal strips and heaters were removed and something like a 555 timer circuit replaced them but maybe they did something different. As mentioned, I believe the first versions of the converted switches were polarity sensitive and were made for the specific year and polarity of the car.

I don't know if the current switches are still specific or if all vendors sell the same conversions but if you run out of other things to check polarity mismatch is a possibility. As you may remember, 55s came with positive ground and had the switch with 3 exposed terminal screws. When they ran out of those switches, for 55 field replacement or if corrosion had occurred they installed the 56 switch with the bullet type terminals in the weathertight box. The old bimetal switches do not care about polarity.

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More things to check. Thanks.

The car is a '56 Patrician with column, not push button, shift. It does not have the manual override.

I assume that you tried the 56 service procedure,
https://www.packardinfo.com/xoops/html/downloads/SC/SC-VOL29NO12.pdf

And the 56 supplement information for help to check the system.
https://www.packardinfo.com/xoops/html/downloads/servicemanual5556/Sect08_Electrical.pdf