: Power door locks problem...



Swedish DeVille Dude
06-09-09, 09:42 AM
Hi guys,
I drive a 1968 DeVille and I have a slight problem with the power door locks.
When I have just turned the engine off the door locks work fine but after let's say a minute and further on they won't work at all.
I suspect that there might be a vacuum leak somewhere, maybe at the vacuum storage cannister...what do you think ?
Cheers from Stockholm, Sweden !

carnut
06-10-09, 06:42 PM
Door locks are electric. 1 solenoid in each door. I would suspect low battery voltage 1st then possibly a worn, dirty master switch at drivers door. Have the battery load tested. Remove switch at driver door and clean it with TV tuner cleaner.

JTL1043
06-11-09, 03:34 PM
I bet your chassie Grounds are croded loss of grounds will not let voltage and amperage Flow. got a 1970 coupe Deville Arizona Car that I have Had too clean up even out here in the Desert.All types of intermittens. Tunner Cleanner is one wire Brush and wd40 on Hingesof Door.
John

sven914
06-12-09, 12:40 AM
Door locks are electric. 1 solenoid in each door. I would suspect low battery voltage 1st then possibly a worn, dirty master switch at drivers door. Have the battery load tested. Remove switch at driver door and clean it with TV tuner cleaner.

This fact eludes many people, but '60's Cadillacs had vacuum actuated power door locks. Through the infinite power of the world wide web, I was unable to confirm if they were used in 68 (you type in 1968 Cadillac Vacuum Door Locks and get MERCEDES BENZ VACUUM DOOR LOCK POWER CONVERSION KIT [WTF]), but I was able to confirm that they were used in 69 Oldsmobile's and 77 Chevrolet's.

So if you do indeed have vacuum powered door locks, then check the hose running from the canister to the doors to see if it is cracked (replace it anyway). If the problem still exists, then replace the canister. If the door locks still don't work right, then have the hoses "smoked." I don't know if they do that in Sweden, but here in the States, some garages have smoke machines which pump pressurized smoke (heated baby oil) into gas tanks, exhaust pipes, EVAP hoses and vacuum lines for leak detection.

Swedish DeVille Dude
06-12-09, 03:17 AM
Yes, I have now determined that my car has vacuum power door locks.
I will check the hose running from the big canister to the doors and also test the check valve at the bottom of the canister with a vacuum gauge to see if it seems to work properly...
Cheers from Stockholm, Sweden !

Will68
09-08-09, 12:36 PM
Just read your posting.

I have a '68 which does have vacuum locking system. Fisher Body manual says the system should hold a vacuum for 48 hours allowing multiple cycling of the lock mechanism.

Similarly to the poster I had a leak in the vacuum system which would not hold any vacuum immediately upon shutting off the car.

My vacuum lines were all fine with no cracks or deterioration. The master unit is located under the dash behind the glove box. I followed and gave each line connection to a module or switch a good checking to ensure snug connection.

The problem was the driver's side locking mechanism. You have to remove the interior door panel to access/work on the mechanism. I did not rebuild it but did a thorough degreasing/cleaning of the unit and found loose connection here. My guess is that driver's side mechanism gets the most use including manually actuating / pulling-up the door lock. The link between door knob and mechanism was binding badly and tough to move. After cleaning and adjusting the mechanism works smoothly without vacuum. System now holds vacuum after shutting off the car but only for two or three cycles of door locking.....better but not factory spec.

I have recently diagnosed one of the storage cannisters having a leak and am awaiting a replacement. This is probably the final fix.

Cost me a few hours of time and little money to fix. And, was a good check-up to rule-out other more costly issues.

Keep in mind that if you have significant vacuum leak the air-conditioning/ventilation/heating system with all of it's modulators and the master control on the dashboard will not work correctly, e.g. you may only get heat, the a/c will not turn on, the ventilation door behind front passenger carpeted kick plate will not open and close (you will hear "woooosh" of air because fresh air door -- operated by vacuum module is not fully closing or opening)