GERALD´S CADILLACS


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ELECTRIC SEAT BACK LOCK IN THE 74 WAS BROKEN AGAIN

I noticed that my power seat back lock on the drivers side once again quit working, when I wanted to let my little boy climb inside the car onto the backseat, and I could no longer move the seat back without unlatching it manually.
I already made 2 previous repair attempts after the solenoid for the unlatching mechanism failed, and for a while it seemed to work perfectly after the repairs were made …

The last mechanism I installed got so weak that it did no longer unlatch by itself when I opened the door…

So I had to order another used unit from my favorite source - Arizona Vintage Parts.
They sent me a perfectly working unit once again - it only had some surface rust, which I removed with rust removing gel once again (see pictures below). After this treatment it looked like new.
Like the last time, I had to disassemble parts of the back seat to replace the defective actuator with a new working one.
The new actuator I installed did work right away, but upon further investigation, I noticed that the latch did not come off as easily as it should, after it had engaged with the striker. On the passenger side the latch does not even touch the striker while it unlatches.
So the solenoid needed a lot of power to unlatch, and when the door was open for a longer period of time the solenoid got pretty hot and would eventually burn at least one of the coils inside. You can only make some minor adjustments to the mechanism itself, and there was no way to get it right on my seat so that it could clear the striker without hanging up.
This definitely already was not done correctly at the factory, and the misalignment of the striker was the reason why the drivers door side solenoid always broke. I´m sure it worked for a while when the car left the factory, but eventually it caused problems.
The only way to make it right was to slightly modify the catch latch. I just had to remove a tiny bit of metal with a file and the mechanism could then move freely, and now the solenoid only needs very little power to unlatch the seat back, once the door is opened.
I hope this is a permanent fix now…

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The new part I got - before cleaning it up
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Removing the rust
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Removing the rust
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The clean mechanism
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I had to file a little bit of material from the edge of the latch, so that it could move freely. They messed up the striker alignment on the seat in the factory.

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REPAIRING THE SEAT BACK LOCKS OF THE 1974 (AGAIN) AND NEW POWER ANTENNA INSTALLED

Today I finally found the time to permanently fix the power seat back locks in the 74 Coupe DeVille. The lock on the passenger side always had a little contact problem since I got the car and only worked sometimes… A guy who wanted to help me and who boasted that he could repair everything, tried to repair it last fall but after his “fix“ it only worked for a day and then the locking system was completely dead, after he had worked on it for hours the day before… Now I did what I should have done before - I fixed it all by myself again…

I found a way to remove the seat back lock mechanism without disassembling the whole front seat and replaced the mechanism with one which I got from my favorite Cadillac Parts vendor - Arizona Vintage Parts. As always they delivered a perfect part and it only took me half an hour to remove the old part and install the new one.

The function of this lock is that it latches the seat backs in place when the doors are closed. The lock disengages and unlatches when the door is opened, so that rear passengers can simply fold the seat backs away when entering or leaving the car, without having to push a button.You can hear this "Automatic Seat Back Release" working when you open or close each door.

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After removing the plastic covers around the seats - it will look like this. The seat back lock mechanism is hiding inside under the seat back.edge
You have to remove the lower 3 hog rings to get access to the two mounting screws.
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The new mechanism I got from AVP on the left and the old original one which does no longer work

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After installing the new part all you need to do is to install the hog rings again and install the seat cover surround moldings. Here I´m using a hog ring plier - but you can use some simple other pliers as well.


DEFECTIVE POWER ANTENNA

I also had to replace the defective power antenna of the 74. The original one had a burnt motor and also the gears and the whole mechanisms were broken. I can´t imagine how this could have happened. When the antenna died it also burnt the fuse. After inspecting the power antenna I decided that it was not rebuildable and ordered a rebuilt one from Arizona Vintage Parts as well.
The antenna can be removed very easily on the 74 - so much easier than on my 60s cars. I was able to switch it out within 10 minutes. It works perfectly now.
It´s very important to me that all things on a Cadillac do work like they should.

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This is how the disassembled original power antenna looked like when taken apart - you can clearly see that the motor was burnt.
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This is how the disassembled original power antenna looked like when taken apart - you can clearly see that the motor was burnt. Also the mechanism itself was damaged.
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The 74 has a working power antenna again.

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TRYING TO REPAIR THE SEAT BACK LOCK MECHANISM ON THE 1974 CADILLAC

The 1974 Coupe deVille is equipped with automatic seat back release locks.
They are actuated by big solenoids which are mounted in the back rest of each front seat.
When you open the door they are actuated, and the seat backs can be folded forwards to allow access to the backseats without having to manually unlock the seat. You can hear this "Automatic Seat Back Release" working when you open or close the according door.

It worked perfectly on the passenger side, and most of the time on the driver side.
When the door was open though you could sometimes hear a rattling sound from the solenoid as it did not make good contact.

That was not acceptable for my standards of course.
You have to remove most of the back seat material to get to the solenoid unfortunately.

Once we got it out, we took the solenoid apart. Some of the actuators insulation foam had crumbled inside the end stop of the solenoid - so we replaced that, cleaned and lubricated everything, and put it back together.
Unfortunately the problem was still there after this.
So we eventually found out that the striker where the seat latches, was not adjusted correctly. Something must have gone wrong at the factory already.
We had to modify it slightly to make it perfect again, so that the solenoid could disengage itself properly when the seat back was in the back position.

When everything was back together it worked for a while before it broke again. I will have to find a good working solenoid now and replace it once again.

UPDATE: You can read about the final repair here!

seat back locks
You have to remove the seat back material to be able to access the solenoid and latch mechanism
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The latch mechanism
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The solenoid disassembled - before cleaning - there are two coils inside.
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A quick drawing of how the system works.

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