Packard Forum Index » V-8 (1955-56)

1956 Executive would not crank. I determined it wasn't in park due to the 9 amp fuse being blown. This is the fuse that is added to the Red/White and Orange wires when the park relay is removed per a Service bulletin, STB 56T-25. I replaced the fuse and the push buttons started to work and the car would crank and start. That worked for 10-20 times then the fuse blew again. Using a jumper at the fuse I could tell there was a dead short when P was pressed. Any other button pressed and the shift relay clicked repeatedly. After testing all the buttons I tried P again and the short was gone. So I guess the question is, why would the fuse blow when P is pressed?

Could be a few areas.

Shift relay.

Sector.

Fingers.

Connectors.

PB buttons.


If you can. Make up the test light for push button

It helps..

Hh56 should reply.. And he can add more in depth

I did more testing. First I replaced the fuse holder with a 10 amp circuit breaker. I also hooked up the R/W and O wires 1 at a time. Results are the short is still intermittent and relatively frequent but I can get it in all button positions. Sometimes the shift relay clicks repeatedly before the breaker trips. Looking at the wiring diagram it looks like the R/W wire powers the P, N, R buttons and the O wire powers the D, H, L buttons. I'm going to assume the short is downstream of the push buttons.(?)

This is a low mileage 48K car and is all original but it does have a bad history when it comes to the shifter. The prior owner had removed the actuator after the trans wouldn't shift. He installed a rod and ran it thru the floor in order to shift the trans. Years ago the current owner found a used one and had Bob Aller install it when he overhauled the Ultramatic. The shifter worked fine until recently.

Look at the fingers.

Orange wire and pink wire.

It's best to remove the motor. If you can.


And make this test set up

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It will take a careful going thru to check for shorts etc but a couple of places to check are the fingers and the wires where they exit the actuator as Riki mentioned and also the back of the PB assy for any of the button leaf contacts that might be weakened, damaged or even fallen off. Also check the plugs at the base of the steering column and make sure none of the contact terminals have been pushed out and might be shorting. You mentioned the fuse is present per the tech bulletin but did not mention if the auto park relay the bulletin gave instructions on removal is still in the circuit. If so that has caused some issues in the past if it sticks and keeps power on the park finger because pushing another button makes the actuator fight between the two active positions.

The factory diagram is not the best because it does not show what happens in the relays but here is a copy of the Autolite full schematic showing all the relay contacts etc. The Autolite provided PB service manual is in the literature section if you want to download it and go thru the theory of operation and do some of the testing procedures.packardinfo.com/xoops/html/downloads/AutoLite_ServiceManual.pdf

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Thanks for the added advice guys. I'll pull the PB assembly apart first. Then if nothing is found I'll pull the motor assembly. My gut feeling is that is where the short is. I already checked the under dash connector and it looks good. The park relay is not in the circuit. I can't remember but either Bob Aller removed it 20+ years ago or I removed it 10-12 years ago when I did work on the car. FYI, the wiring diagram I am using is the same one you sent.

Would this How-To: Pushbutton actuator removal guide from the How-To's & Tech Tips section of the Packard Literature and Manuals menu be of assistance?

I have seen them pinched in the case. And where the pushbutton sets.

That would do it! Good job in locating the problem. I don't have any push button shift Packards but I do have a couple push button assemblies from an old dealer whose stock I bought years ago.

I think I may have found the short. The white wire has rubbed on one of the fingers, the green one is starting. Could this cause the fuse to blow? I'm not sure how to fix it other than replace the whole harness. Since the wires are otherwise in good condition I could add an insulating strip. Suggestions welcome.

Another problem popped up. After opening up the PB a contact tab broke off. This does not look like an easy fix. I'll need a tab and figure out how to install it since it is held on by a small rivet.

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