1970 Deville Ignition key and door locks

[colorado4x4]

My square ignition key for my 1970 Deville convertible does not work on my door locks. (not sure why, could be a variety of reasons, was definitely not a dealbreaker when I bought the car)   Round trunk and glove box key is fine.

Looking for suggestions to rectify:

Get a new or used matching ignition and door lock set   (how hard is it, and what is involved, to remove the ignition lock and the door locks)

or have door locks re keyed to the ignition lock key  (is that possible, perhaps an old school locksmith?)

or some other scenario?

Thoughts?

[TJ Hopland]

Does the round key work in the doors or don't you have any key that works?  Can you manually lock and unlock the doors?  Some years are really prone to having the locking mechanism corrode and get stuck. 

Also I was thinking by 70 they had switched to the round key also being for the doors.   Square was just for the ignition till the 90's when they went to a single key for all.

[Cadillac Fleetwood]

The square key is for the ignition and the doors in 1970.  The specific key-way style is stamped on the key.  The letter J appears on the square key, K on the round key.
Each lock cylinder is stamped with a four-digit alpha-numeric code, for example, "5J39".  You can remove one of the door lock cylinders and find this.  The ignition cylinder is also stamped, but is more complicated to remove, because the steering wheel must be removed.  Locksmiths, at least the old-time ones, were able to cut keys based upon these codes.

If your key fits the ignition, but not the doors, then have the door locks re-keyed.  If your ignition key fits the ignition and one door, but not the other, then the "non-fitting" door may have been replaced as part of body repairs.  I may have a complete matching set of ignition and door locks.

Charles Fares

Edit:  Send me an e-mail with your contact information and I can explain how the interior door panels are removed.

[cadillacmike68]

I'm not sure exactly when they started this, but at least from 1967 on GM used a 2 key system with the blanks having letters. 1967 was A & B, 1968 was C & D, 1969 was E & H (E for "Engine" and instead of F they used H for hood- trunk??) and 1970 was J & K. Then it repeated back with A & B. Perhaps F looked too much like E and a worn key would be mistaken, jammed into a lock, and broken. That's my guess.

The first letter (A, C, E, or J) was for the doors and ignition, the "square" key. The second key B, D, H, or K), the the "oval" key, was for the glove box and trunk. This was good because you could lock the glove box and trunk, and give the door / ignition key to a valet, and they couldn't get in to the locked areas.

Eventually the first key ended up being only for the ignition.   This was definitely the case by the time PASS Key / VATS came along because the Ignition key with it's resistor chip would no longer fit in a door, but I don't know when this was started.

[Scot Minesinger]

I have three 1970 Cadillacs and suffered the same problem. 

The square key works the doors and ignition, with the idea being back then, you hand the valet the square key and lock valuables in trunk or glove box.

Anyway, the problem is very likely a bad k-mart type key duplication.  I had the original square key in the 1970 Caddy that worked the door and ignition.  After it was duplicated at HD, the duplicate would only work the ignition and not door lock.  I drove the car to a lock smith and had them duplicate the original key and the locksmith made key worked the door lock and ignition.  If you have the original key that works door and ignition, then you can go my route, otherwise maybe the locksmith can figure out the flaw in the duplicate key? 

[colorado4x4]

Thank you for all the responses,   as I look at my keys, I see the square key is an ACE Hardware copy with a "C" on one side and "B50" on the other side. The round key looks to be an old GM key with codings "B47 K" on one side and "replacement for GM e.s.p lock corp" on the other.   

If the "C" key code aligns with B50 and the "K" key code aligns with B47, what does a "J" key code align with, Bxx?

So it seems my square key needs to be a "J" key instead of the "C" key that I have.  My car is offsite at the moment, but I know the key works fine for the ignition, will go over today and revisit.   
Looks like, at some point soon, I will need to take a door panel off to get the code on the door lock cylinder, then get a J code key made, then see if it works on the door and ignition. and maybe get an"old school" locksmith on retainer.

Will report back on the all the  hoops I'll be jumping through to get this resolved !

[Kurt Weess]

I went through the same thing on my 70 Fleetwood.  I had 3 keys for the vehicle.  One for the ignition, one for the door, and one for the glove box / trunk.  My original "J" ignition cylinder was replace with an "E" cylinder at some time while the doors retained the original "J" lock.  Since the door cylinders are much easier to replace than the ignition cylinder I just purchased 2 door lock "E" cylinders and had them re-keyed to the ignition code (the "E" key actually had the cylinder code stamped on the key).  I couldn't re-key the original "J" lock since the keyway was different.  A good locksmith should be able to re-key new "C" door lock cylinders to your existing "C" ignition key.  See attached link for key code years and keyways.  On the left you can select Cadillac for options to purchase.

http://www.carlocksandkeys.com/blog/all-about-gm-general-motors-lettered-square-and-round-key-blanks/

If your goal is simply to get a working key for the door lock they you can, as stated earlier, pull the lock cylinder and get the code for the door "J" key.  But your new "J" key will definitely not fit your "C" ignition since the keyway is different.

Good luck!

[colorado4x4]

Wow, where did two years go.....finally circled back around and got working on this "key" project. 

Synopsis:
My ignition lock key cylinder on my 1970 Deville convertible, at some point in the past, got changed from the original J code lock cylinder to a C code cylinder, therefore the C code key would not/will not work in the door lock cylinders.  Went to my trusty boneyard and found some C Code door lock cylinders from a 1968 and from a 1972 Deville.  Took the C Code cylinders to the locksmith at Bear Valley Lock and Key and he re-keyed the lock tumblers to work with my existing C code ignition key.  Now just need to take the door panels apart to swap out the J code door lock cylinders to my "new" C Code cylinders.

Any best practices/techniques to taking the interior door panels of of 1970 Deville convertible, or is it pretty straightforward?  Seems it will be straightforward, just don't want to break anything unnecessarily.

The boneyard door lock cylinders were easy to remove from the parts car as the interior panels were already long gone. They are essentially only held on by a large C clip, which was easy to pop off with a needle nose vise grip and long screwdriver.

Looking forward to just having two keys for the car....one for the ignition and door locks and one for the trunk and glove box ! 

[William Korkshire]

Wow, where did two years go.....finally circled back around and got working on this "key" project. 

Synopsis:
My ignition lock key cylinder on my 1970 Deville convertible, at some point in the past, got changed from the original J code lock cylinder to a C code cylinder, therefore the C code key would not/will not work in the door lock cylinders.  Went to my trusty boneyard and found some C Code door lock cylinders from a 1968 and from a 1972 Deville.  Took the C Code cylinders to the locksmith at Bear Valley Lock and Key and he re-keyed the lock tumblers to work with my existing C code ignition key.  Now just need to take the door panels apart to swap out the J code door lock cylinders to my "new" C Code cylinders.

Any best practices/techniques to taking the interior door panels of of 1970 Deville convertible, or is it pretty straightforward?  Seems it will be straightforward, just don't want to break anything unnecessarily.

The boneyard door lock cylinders were easy to remove from the parts car as the interior panels were already long gone. They are essentially only held on by a large C clip, which was easy to pop off with a needle nose vise grip and long screwdriver.

Looking forward to just having two keys for the car....one for the ignition and door locks and one for the trunk and glove box ! 

I wonder why the J code lock cylinder was changed to a C code cylinder. I'm just curious because as far as I know, these two aren't compatible with each other. You can take the cylinder to a locksmith near me sw9, to be rekeyed and reprogrammed once again. I don't see other solutions in this situation.

[The Tassie Devil(le)]

I would say that it was done for security reasons, simply because GM made many makes worldwide, and with Chevrolet and Pontiac using A and B keys, not sure what Oldsmobile, and Buick used, and Cadillac the C and D.

I believe the simple differences is the shape and position of the slot that is in the full length of the key shafts.

This change lessens the chance of keys being the same code and therefore increased security.

I remember that the key for my 1957 Chev would open a 1974 Holden (Australian GM) and the owner was amazed that this occurred.

Plus, changing the Coding was a simple way to allow advertisers to give a further separation of the "lesser" brands from Cadillac.

Bruce.  

[dochawk]

There was a time in which there were only a silly-small number of distinct GM keys.  19? 37?  So there was a non-trivial chance of starting another random gm vehicles.

I got the tale decades ago from someone who had been driving home, and turned down his radio.  Which in turn caused him to think, "I don't *have* a radio!"

he drove back to work, got out of the same make and color car and into his own . . .