Packard Forum Index » V-8 (1955-56)

Here are a couple of schematics on the pushbutton shift elctrics taken from the Autolite repair guide. Made them awhile back to sort out a problem. They were reworked to show the approved and mostly shipped version without the very early control relay. The second one is similar but reflects removal of the autopark relay per tech bulletin 56T-25. The suggested additional fuse is shown on both versions.

These schematics may be a bit better for troublshooting as they show the system with relay contacts and motor windings in the circuit rather than trying to guess what was happening with the Packard versions.

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Park Relay special note:

The park relay is NOT affected by the pressure sw. WHICH MEANS that if the ign. sw. is turned OFF while at speed then the system will attempt to shift the trans into Park. NOT a good idea.

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Auto-Lite even admits this in their Service Manual for the pushbutton control.

I'm wondering why Packard didn't wire the auto-park relay to the pressure switch, then.

Seems to me that if you remove the green wire on the park relay that is fed from the circuit breaker, and then run a new wire from that same relay terminal to the pressure switch terminal that feeds the selector buss bar for the "N", "R" & "P" switches, that problem could be alleviated. No?

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If I understand your suggestion correctly, I think no. The feed for the pressure switch comes from ign switch so when ign switch turned off, there would be no voltage to pressure switch or PBs so everything would stay in the state it was currently in. With the way they did it, key off, relay drops out and connects the battery to the park terminal in selector directly just as if the button were pushed.

It is a downside for sure and I'd bet responsible for more than one interesting experience.

BH: For a strictly academic exercise i mite study your rewireing idea soemtime this afternoon.

However, i think at this point just the fundemental concept of an 'auto park' function is a general absurdity at best. And obviuosly was not taken serious by AL nor Packard in view of the possible major malfunction that would take place if the ign were turned off at speed.

THe conceptual absurdity of an automatic park feature regardless of how it works or does not work is a conspicuous reflection of the gross incompetance that Packard must have suffered from in its last years.

Perhaps I misunderstand all this, but doesn't simply following Packard's TSB to eliminate the "auto park" feature solve the problem of inadvertantly going into park if the ignition accidently cuts out?

Howard -

Oops, I didn't think that through far enough.

I was looking at the diagram in the Auto-Lite manual, rather than your updated one, but I didn't even pay attention to the control (battery) relay, which interrupts power feed to the pressure switch.

Of course, that circuit should be opened to deactivate the buttons when ingition is not switched on.

The control relay was eliminated, once it was realized that the park relay could perform same function. However, when the part relay is eliminated, the circuit is controlled directly by the ingition switch.

Keith -

You wrote:

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Don't bother - as, Howard noted, it won't work. I suppose one could rig up a second switch, but it's not worth the time.

Acutally, I think the auto-park concept is a neat trick - providing the car isn't moving.

It's no problem for me to turn the ignition switch to the ON position to keep the car in neutral, then disconnect the battery, if I need to move the vehicles with the engine NOT running.

Otherwise, I think it would be very rare that the driver would intentionally turn the ignition OFF while the car was still moving, but not unthinkable.

IIRC, only one of my pushbutton-equipped Packard has the auto-park relay disconnected, but I plan on reconnecting.

Owen -

I'm aware of that STB, but was looking at some way to retain the auto-park, yet temporarily bypass that function if vehicle was still in motion - without getting too complicated.

Two incidents:
#1, I ran out of gas about fifty feet from the gas station I was headed for. I got out and started pushing keeping the momentum so I could get up to the pumps. As I was pushing I thought "I'm burning the points, better shut the key off". I reached in and with my right hand switched off the ignition. I heard the shifter and knew I had blundered, but before I could reach in and turn the IGN on, the automatic Park engaged and I rammed my head into the pillar and the roof - damned near knocked myself out.

#2, I had pulled the car into a car wash which back then was pulled by a chain in the floor and the link they hooked on to your lower control arm had a weak link designed to break and prevent damage. The young boy who was cleaning the inside of my windshield and wiping off the dash noticed I had left the ignition on. He obligingly turned it off. The front end dipped down, the link snapped, the young boy almost turned white, which was not his normal complexion. I had leapt the short wall which kept patrons out of harms way and turned the key on. He was stammering and professing he didn't do anything wrong. No damage to me that time. I figured out which wire to disconnect and all three of my 56s have the fused bypass installed.
Haven't hurt myself in that way for a long time.