Packard Forum Index » V-8 (1955-56)

Hoping someone can shed some light as why I cant seem to get the stop lights on my 1956 Patrician to work. Have tried 3 new 3 pin brake light switches to no avail. If i take the brake light wire out of the 3 pin plug and apply auxiliary power to it the lights work as they should. The outlet that feeds the torsion bar works fine. I have made sure the hydraulic fluid is at the fitting so there is no air gap. Yes the motor was running and the treddlevac works.
Hard to believe a new 3 pin brake switch still in the boxes could all be faulty. any thoughts please.

Have you put a meter across the brake circuit of the switch and tested it?

You can also test it by raising the back of the car with the levelizer and then shutting off the suspension at the under dash switch. The swap the brake and suspension wires at the 3 pin switch. Now the brake lights should be on and go off when you press the brake pedal and when you switch the suspension back on, it will only go back to level when you keep your foot pressed. on the brake pedal.

Next would be fluid pressure to the switch. When you bled the brakes, did you bleed the switch?

You could also pick up a 2 pin brake light switch and see what happens.

Next would to be to put a pressure gauge at the switch location and see what you have by way of pressure.

One possible issue is the terminals on the new switch have a different layout from the old switch. The symptoms sounds like the input voltage might be on the wrong terminal..

Packard issued two diagram versions of how the switch terminals are connected and a third was found to be the case with a different brand switch. I do not know if one of the Packard versions was incorrect or if they actually had different configuration switches in 55 and 56 but you might try all 3 combinations and see if one works before deciding the new switch is bad.

An easy test would be remove the wires from the switch and then use an ohmmeter to try the various combinations. With the switch just sitting continuity should be between COM and N.C. with no connection between COM and N.O. When the brakes are applied it should switch with continuity being between COM and N.O. with N.C. disconnected.

Many thanks to you both for your advise.
HH56 you were on the money. Different make switch same 3 pin layout but different combination. Although I'm 86 I should have picked up on that myself.