Packard Forum Index » V-8 (1955-56)

1956 400 push-button problem. Last week after driving the car for an hour or so it would not shift out of reverse. I turned the ignition off and tried to restart it. Of course it did nothing since it was still in reverse. After the car set for a day I turned the ignition on, pushed the neutral button and I could hear the acctuator working.I started the car and put it in different gears,L,N,R,D, Sometimes it wouldn't shift. This was sitting in the garage. I eventually turned the ignition off with the car in reverse.I turned the key to start and it started in reverse.I have an old motors manual but nowhere in the trouble shooting can I find a problem like this.Any suggestions?

Mr Pushbutton should be along shortly and am sure he will have some suggestions. In the meantime, if you would like more information on the system here is a service article by the manufacturer of the unit. It contains much more information and troubleshooting than will be found in Motors.https://www.packardinfo.com/xoops/html/downloads/AutoLite_ServiceManual.pdf

Sounds like a bad safety switch. It is HYDRAULIC and located on the left side of the transmission. U can bypass it by removing the wires from the switch and connecting them together.

Could just be bad connexion at the switch too. Try cleaning the contacts.

The governor-activated pressure switch should only affect response of the "P", "R", and "N" buttons - even when it fails. If the "D", "H" or "L" buttons are unresponsive, that might rule out the pressure switch as a problem

Also, the start relay should prevent operation of the starter motor if any button other than "P" or "N" is selected. Odd, then, that the car started in reverse.

With only this much info, I'm thinking this car may have a wiring problem. If so, MrPushbutton can certainly help with that.

Until we hear from him, you want to download the Auto-Lite Service Manual: Packard 'Push Button' Transmission Control, which HH56 generously contributed; it has some extensive diagnostic info. In fact, I noted it as "recommended reading" in the Model Info pages for all 1956 cars.

"Last week after driving the car for an hour or so it would not shift out of reverse."

AND
"I turned the key to start and it started in reverse"

First quote indicates the pressure sw. is hanging open after having driven the car enuf to build pressure.

The second quote indicates the pressure sw. is hanging closed.
i.e. the pressure sw. mite be hanging up either open or closed and doing it sporaticly.

Of course there could be wireing problems as BH indicates or even relay problems beyond the pressure sw.. The pressure sw. is ez enuf to bypass and to eleminate from the system for diagnosing the rest of the more complex system.


Try this before u do anything:

Select "N" always before selecting ANY other button. Select the buttons slowly. See if that solves the problem.

I agree that an intermittent problem with the pressure switch could be one reason why the actuator would not shift out of reverse at times

However, I can't see how a failed pressure switch would allow it to start in reverse. Again, the starter is locked out by the start relay and when any other button than "P" or "N" is depressed. The condition described would more likely be a problem with response of that relay, though not necessarily the relay itself.

There could be more than one cause at the root of the matter. Yet, these symptoms could actually involve separate, unrelated problems.

Of course, all of it can be remedied if one takes things a step at the time. Again, the Auto-Lite manual provides some execellent troubleshooting info.

Thanks so much for the information it should help alot

There is a plug at the end of wire coming from PBs at steering column. Those have been known to cause problems so would check that and make sure all the contacts are well inserted in the housings. The usual poor contact or burned fingers at the sector could also be causing the problems. Possibly heated up with the driving and breaking contact until cooled down again.

No explanation for the starting in reverse but one possibility on the no shift at all is at the automatic park relay---if yours has it and has the revision that eliminated the control relay. When the key is on, the park relay functions as a tie point to provide power to the wires going to pushbuttons. One directly to L,H,D and other via the pressure switch to P,N,R. Those are fed directly from ign switch by yellow or white wire tied at the ballast resistor. A bad or loose connection at one of those places could cause the symptoms.

If you still have the control relay, the same basic path to pushbuttons apply except ign switch closes the relay and an intermittent bad contact in the relay could cause problem.

Somebody call me?

Good advice all, especially re: the pressure switch. I would check the switch, they are availble through the parts guys. I would ohm out the orange wires in the PB harness, the wires that go to the pressure switch. one wire goes into the connector under the IP, the other goes to the fork terminal on the fender well. There have been incidents of those wires suffering meltdowns due to a short somewhere else in the system. All of the power for the logic circuits go through the orange and red/wh wires and the reliability of the system is dependent on every "link in the chain" being 100%.
Re: the starting in gear, get the wiring diagram from the Autolite book (all of them) and compare with what's going on with your car, I suspect some "improvements" have been made, not for the better.
Howard--if the contact finger is heating up it is because the finger is contacting ground at the open end, a rare, but not unheard of occurance. When this happens the finger will glow orange like a stove element, and at that point the temperment is gone out of the finger, and it won't repeatably make contact.
I have done a lot of repair of meltdowns in the finger harness. I am working on a reproduction harness, with the molded rubber block, exactly like the original, I hope to have it available by the next Perrysburg/Fremont event, and available for my customers.
I rewire all motors now, the insulation is all over half a century old now and crumbling. The finger (logic) harness is equally as old, although that wire seems to stay "live" longer. It's still old, and so many of the units have had various meltdown episodes, and then there is the topic of
monkey-work. This system had its teething problems, and there were issues when new. Every garage mechanic who can probably rebuild an engine or transmission, and make sensitive adjustments intellegently thinks they are an auto electrical expert and the blue-crimp connectors abound!
Look the whole thing over closely, even to the point of un-wrapping the logic harness to examine every inch of the wiring for meltdowns and "improvements".

33 Su8-Any update? just wondering how you made out.