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…

The new part I got - before cleaning it up

Removing the rust

Removing the rust

The clean mechanism

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.

Tags:1974 Cadillac Coupe DeVille, 1974 Cadillac Repair Tip, 1974, Restoration, Seat Back Locks, Actuators