News:

Due to a technical issue, some recently uploaded pictures have been lost. We are investigating why this happened but the issue has been resolved so that future uploads should be safe.  You can also Modify your post (MORE...) and re-upload the pictures in your post.

Main Menu

'72 Coupe Deville electrical oddity

Started by Dynamic88, October 22, 2015, 04:59:30 AM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Dynamic88

Hi there! I just acquired a 1972 Deville and drove it home from upstate the other day. Loving it so far, but there's a curious issue with the driver's side door jamb light switch. When the driver's door is opened, the interior lights do not light up, however they do light up when the passenger's side door is opened.
Strangely, the Stop Eng Temp light on the dash lights up when the driver's door is opened, so it seems that the switch is doing something, if not the correct thing. I believe this is with or without the motor running, and without the key in the ignition.
Both seat lock release switches work just fine.

Other odd thing is that the horn relay makes a sort of whining sound whenever it's plugged in. Horn works just fine when the relay is all hooked up, of course.

The windshield wipers don't work correctly. I turned them on to clear some light rainfall from my windshield, and they stayed on even when I returned the switch to the off position. The washer fluid reservoir is empty, however the "Low Washer Fluid" light on the dash only lights up when I fidget with the switch (or maybe when I press the washer button, I don't recall what exactly made the light come on).

I thought the blower motor being on low at all times with climate control set to "off" was a malfunction as well, though if my sources are correct I guess that's just a function of the car's "flow-through ventilation" system.

Other than the few odd problems, the car runs and drives great and was knocking down about 15-16 MPG on the way home doing 65 most of the way. ;D Hopefully it won't be too stubborn with these few electrical issues. Thank you for any and all assistance!

jwjohnson86

Have you gone through the fuse box and checked all courtesy light bulbs?  I found bad fuses and bulbs in mine, most everything came back on after replacements.
1970 DeVille Convertible 472 cid

http://bit.ly/1NhHpdt

Scot Minesinger

Yes, agree check all the fuses and bulbs.  Then clean and plug back in any engine bay connectors between starter and fire wall - they corrode easy.  The door switch on drive side door jam is probably dirty or bad.

Enjoy your Cadillac!
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

TJ Hopland

The seat release and lights are different physical switches in the door jam.  The stop engine light is normal for a 73 so it may be normal for a 72.   It has to do with the way the seat belts, stop temp, and key in ignition all use the same buzzer.   I was not sure a 72 had the seat belt thing but maybe they did.  If they did you could find interesting modifications done over the years to try and keep the buzzer from going off since no one ever used seat belts back then.  I believe the switch in the drivers door has 2 sets of contacts in it, one is the usual one that grounds for interior lights and the other set is for the buzzer mess.  This would explain your situation where the lights don't work but other things do. 

The fluid light I think only lights when the wipers are on.  Lots of people have reported that at this age the float for the sensor quits floating so the light won't go off even if its full.   I think people have said baking the float in an oven at a low temp fixes it.   Why they stayed on is another question.  Sounds like an issue with the park circuit.  Because of the 'hide away' design there is a kinda wacky cam mechanism that changes the stroke of the wipers when they are running so they don't drop down each cycle.  They should stay up above the hood line when running.   When you turn the switch off a solenoid kicks out which then is supposed to let the stroke change so the wipers drop down.   I think the same cam that lets them drop also contacts the park contacts that then kills the power so they stop.   IF that park cam thing is gunked up or something is bent up in the linkage it can't quite fully park so it runs another cycle.   I don't remember the 72 when you push wash does it mechanically move the wiper switch to lo?   If not then there could also be additional 'electronics' involved in making the wipers start (and stop) running for a wash cycle.  The later vintage that had the delay option had a small electronic board as part of the wiper assembly that was not especially reliable when they were new and with age pretty much don't work.   

Blower runs any time key is on.   If the ac system has a charge in it the compressor will run in all modes but vent. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Dynamic88

#4
Thank you for all of the replies!

I don't think the washer button activates the wiper switch in any way, at least it does not in my particular car. Yes, all of the fuses appear good, although I notice that there's an empty fuse slot beneath the Wiper fuse that is unmarked-- Would this happen to be a spot for a second wiper fuse that's supposed to control the park function? I can't see the left tabs, so I can't tell if it once housed a fuse and the tabs broke off or backed out, or if that's how it left the factory.
Before I drove off, the previous owner did mention something about the wipers not working correctly because the wipers had two fuses and the tabs for one fuse broke off, but then I've heard lots of faulty explanations for malfunctions from people selling me cars.

As for the seat belt buzzer, it still worked when I got the car, actually. Just today my friend kept complaining about the buzzing anytime he didn't hurry up and get his belt on before I put the car into gear at each stop we made, so we flipped open the plastic belt housings on either side and disconnected the wires there. No more seat belt buzzer, but it hasn't helped or hurt any other functions.

As for the horn relay mentioned previously, I plugged it back in for more testing tonight. I take it the horn relay does double-duty as the "key in ignition" buzzer as well? It buzzes constantly when plugged in, unless the doors are closed (door jamb switches depressed), even with the key out of the ignition. I've seen trouble reports of the buzzer coming on and staying on at all times, regardless of doors being open or key in ignition, but since mine doesn't buzz with the door shut, would this point to a dirty/bad ignition lock switch? Any way of fixing this without replacing? Seems just fine otherwise.

Glad to know the temp light is just an odd early '70s Cadillac quirk. I'll investigate the driver's side door jamb light switch contacts a bit more to see if I can get it working properly. One set of contacts being dirty or corroded would make a lot of sense, since everything except the lights reacts to the switch being pressed in, including the malfunctioning key-in-ignition buzzer.

Once again, thank you for all the help. I really appreciate it!

Dynamic88

Little update: The windshield washer button does in fact have a cam to turn on the windshield wipers. I disassembled the driver's side door to lubricate the window guides and door lock/latch linkages, and in the process found that the contacts in the wiper switch were rather gunked up. I cleaned them up and put it all back together, though right now it seems a bit reluctant to start the wipers (though now when they run, they actually shut off and park when the switch is returned to the off position).

I've noticed that both doors have a latch issue, wherein the latch has some side-to-side play when in the fully locked position, which allows the doors to rattle in and out a bit when fully closed. I'm curious, is there any adjustment that can be made to tighten that up, or is the only solution to replace the latches?

Didn't get around to removing the door jamb switch to inspect it, but I felt around behind the kick panel and believe I felt a contact terminal with no wire connected to it, so perhaps the contact that's supposed to turn the lights on when the door opens is disconnected entirely.

Also going to have to open the passenger's door soon to get at the lock actuator, as it doesn't seem to want to lock that door (and is holding up the linkage so the lock cylinder and lock knob also have no effect). With any luck it'll just be a bit corroded and jammed up as a result, which wouldn't be much of a problem for me to remedy.

Tomorrow I'll probably be further investigating my front side markers/cornering lamps. The driver's side marker light works, but the pass side marker and both cornering lamps don't seem to want to work even with clean contacts and good bulbs.

Guess there always comes a price to pay when you pick up a great car at a bargain. Fortunately, it's all exciting to me!

Scot Minesinger

On the doors side to side play (side to side perpendicular to car body, not parallel - right?), my understanding is that they compress a set of rubber stops and of course the weather stripping to keep from rattling.  The rubber weather stripping and stops probably need to be replaced.  I bought a set of door weather stripping and stops plus many other rubber parts for my 1970 Cadillac SDV from Steel Rubber.  The door latch post on body that the door latch secures too when closed is adjustable, by loosening (use the star tool, not vice grips), repositioning and then re-tightening.  If you adjust it to no rattle and the rubber is gone, then the door might look too far closed when shut.

Even a super low mileage Cadillac that is not bought at a bargain have these issues too.  You just have to go through them and find out what is wrong and fix the issues.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

"Cadillac Kid" Greg Surfas 15364

The door latch "post" attached to the door jam is supposed to have a plastic collar called an insulator on it.  When these are worn or missing it is near impossible to keep the door from rattling.
I am glad you are getting the bugs out of your car one at a time.
Regarding the door lock actuator, what I have tried successfully is spraying (something like ) WD-40 in through the opening in the door end, looking down through the opened window cslot to aim at the top of the door lock actuator.  If they are sticking it is in all likelyhood because the rubber cap over the end of the actuator is deteriorated, allowing water to get to the solenoid.  This can work in your favor since now you can get lubricant in.  Spray, work the door lock manually by the button and repeat.  That failing to work yes, pull the door panel and get to the actuator to free it up.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Coupe Deville

On my project 72' the drivers door would lock, but just didn't have enough juice to unlock (go back up). So I pulled the rubber boot off the actuator and I sprayed wd-40 right into the hole were the metal rod slides. It worked beautifully after that. That was the only way I was able to free it up. 

Good luck with your purchase, I'm glad to hear that someone els is keeping these 72' Devilles on the road. I have 2.
I'm 17, and I wonder where all of my money went. But these cars are so worth the work!! Keep up the good work.

-Gavin
-Gavin Myers CLC Member #27431
"The 59' Cadillac says more about America than a whole trunk full of history books, It was the American Dream"

Dynamic88

#9
Scot- You may be right on the rubber parts. The weather seals are much better than on the AZ cars I'm accustomed to (this one spent its whole life in Colorado until a few months ago), but the rubber stops on the doors are either missing or hardened and probably shrunk. Funny thing though, I tested the latch on my '69 Bel Air earlier today, and it also has some side-to-side play, perpendicular to the body, when it's fully latched, but that door stays totally firm and in place. Plastic insulator is also gone from its door jamb strikers, and the weather strips are virtually gone on that car. Very strange indeed.

I noticed that the Bel Air's latches sprung to the open position when I pressed the button on the door or pulled the release handle on the inside, whereas on the Cadillac it seems that the door jamb striker pulls the latch open when the door is being opened- No spring action on either latch. Does that sound normal? Doesn't seem like it to me, but then there's three years' difference between the cars I'm testing so I wouldn't really know.


Greg- Good call on lubricating the actuator from above, I'll give that a try. Hopefully that'll free it up once some lubricant soaks into it. Seems like a pretty robust little actuator unit, so I doubt it's beyond repair.


Gavin- Glad to hear that you got your actuator freed up! I'll be trying that soon myself and will report back with the good news once I get it working again. A matter of when, not if. :)


In other good news, one of my friends clued me in on a fairly large one-owner junk yard on the other side of town that allegedly has a number of early '70s Cadillacs, and lets go of parts for relatively cheap. Gonna start compiling a list of parts I should see about replacing. This means I'll have to try diagnosing the climate control system sooner than I expected to. Hopefully whatever's wrong can be cured with a trip to this yard.

Coupe Deville

-Gavin Myers CLC Member #27431
"The 59' Cadillac says more about America than a whole trunk full of history books, It was the American Dream"

Dynamic88

I'll be sure to get some when it's light out tomorrow, perhaps some before-and-after action. A friend and I are actually going to start repainting her. Her paint's a bit ugly right now, admittedly.
According to the body tag the car was Zodiac Blue with ?? vinyl top (24-J is the color code). That would look very nice, but unfortunately, the previous-previous owner sanded away at a lot of the paint, threw flat brown primer over half of the car, and mis-matched the colors of the fender skirts. The next owner left it all as-is. Given that I don't currently have money for good, authentic Zodiac Blue paint, we're just going with something a little different and more budget-friendly for the time being... I'll get pics up as soon as I have 'em!  ;)

Also, just got back in from tinkering with the Q-Jet. The carb's in decent enough shape and everything seems to work on it, but the secondary choke plate was stuck closed due to lack of lubrication, so the engine would be starved for air and would bog horribly when the secondaries opened. Not anymore!

Scot Minesinger

Also, make sure the strikers on body that the door latch grabs are installed as Greg suggested.  They are sold on e-bay for low cost and look like a 1/2" long cut piece of plastic tubing.  Go on e-bay and type "1972 Cadillac door strikers" and it should come up.  When you see them you will get how they are installed.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Dynamic88

#13
Happy belated Halloween, everyone!

Roger on the door strikers, will probably not bother with replacing them until I can afford and find the time for hinge bushing replacement. Hopefully I'll be visiting that junk yard with all the old Caddies early next week, maybe I can test the function of other latches (still not sure if mine are supposed to spring to the open position when the door release is pulled, like my '69 Chev latches do). Probably still a ways away on that.

Just waiting for the paint to fully cure on the roof before I go snapping the divider trim back in place. All other trim that I have is back on the car now, minus the trunk lid lip trim, which I need to find the appropriate screws for still. Will get pictures once that's sorted out.

Got the windshield wipers working... for a bit. I removed the connectors from the motor, cleaned them up a bit, then reconnected and they worked properly going through all the ranges, including "mist". Then they stopped working properly again, later that night. I'll probably just have to do a real deep cleaning of all those pins and sockets. At least I now know that the wiper motor isn't shot. :)

I may have found out why my climate control doesn't want to heat the car or defrost my windshield. At least, I hope I have. The vacuum line that connects to the engine's intake manifold was disconnected, though the port was properly capped. Unfortunately, the hose itself was also hanging by a thread from the firewall grommet it passes through. Tomorrow I'll be going to get some fresh vacuum hose and hook that up. Perhaps then my vacuum parking brake release and ATC will finally work. It's looking promising with the ATC system, but I'm not holding my breath. It's really hit or miss, I find, whether these old cars have blown out vacuum diaphragms or rotary valves under the dash or not. I'm definitely not out of the woods yet. Working defrost and heat would be really nice to have with winter approaching, though.

It appears the ambient temperature sensor is still functioning, thankfully. The "flow-through ventilation" function of the blower doesn't engage when it gets really chilly outside, which I recently read was a change GM made due to customer complaints with 1971 models blowing cold air into the car before the heater could warm up. Makes perfect sense, but it sure worried me until I researched that.

Also on the agenda for tomorrow, lots of rust removal in the trunk. Lesson of the day: Don't take the rear marker lights out of the car and park it outside for a year!
Now, since my hands are effectively tied until tomorrow, I guess it's time to have a beer or three. ;D

Jeff Rosansky CLC #28373

Are your hands free enough to take some pictures?
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

Dynamic88

Yup, I finally got it back together last evening. I'll be taking some photos during daylight, since my camera takes abysmal photos in any level of darkness. I'll get them to ya, I promise! :D

Today I got that vacuum line replaced, now the parking brake release and air diverters work beautifully, car has full defrost and working heat! ...Except I think the heater core is leaking a bit. Smells slightly like antifreeze with the heat engaged, and the defrost mode leaves a hazy film on the windshield that requires some elbow grease to remove. Probably just going to pepper the radiator and deal with this sometime down the road, I still have a heater core to buy and install in an Olds so don't have time or money to pursue this. At least the vacuum stuff all seems to be intact!

I have a constant click-click-click sound from the ATC programmer with the control head in the "Off" position, perhaps something sticking? Haven't had time to investigate yet. At worst, perhaps a vacuum diaphragm beginning to let go, but not entirely shot? Vent mode redirects fresh air to the center vents just fine, so I'm sticking with that for now anyways.

Re-spliced some wiring, as well. For some reason one of the dingbats who owned the car before me cut and crimp-spliced all of the lighting/horn wires near the front of the engine bay, and I mean all of them, except the fiber optic cables which are ruined. Some of the crimps were good, some were shoddy, so I've been sorting through the bad ones and re-splicing them. Still trying to figure out why my right-hand cornering and front marker light aren't lighting up, might just be crusty light sockets not providing good power or ground to the bulbs since the wiring looks good and correct.

Definitely loving the way this car sounds, cruises, looks, floats... And it's taken me less than two weeks to iron out most of the bugs! This has been an unusual car for me. Lots of tireless effort has gone into making everything work right, but I've probably spent less than $15 in parts to totally transform the car. Besides my first car, I've never encountered a situation like this!

Scot Minesinger

The click click sound from the ATC programmer means it is hunting and cannot get onto a proper position based on feedback of the three temperatures it measures (inside), (outside ambient), and (discharge supply air).  Check all the wiring connections (sometime the spades back out of the black wiring harness connections, and check all the under dash vacuum connections.  More than likely the programmer is on its way out.  However from when it starts clicking until failure (failure is always obvious when fan only works on high speed) can be some time (years).  Cadillac Tim in Iva, SC (google him) sells good rebuilt programmers.

These really are great cars, glad you are enjoying your Cadillac!
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Dynamic88

#17
The ATC "hunting" stopped happening yesterday, thankfully. As the temp wheel is moved from extreme to extreme, the appropriate air-handling changes seem to take place as needed. Auto mode blower speed does vary depending on desired temperature, only blows at full speed when set to High or when the desired temperature is extremely different from detected temperature. Perhaps with a bit of luck I'll just need to get under the dash and lubricate the accessible moving components to make the programmer's life a bit easier. AC compressor does run, I hadn't noticed until I heard a loud chattering under the hood and lifted it to find the compressor engaged and spinning... Low on freon, indeed. I'll have to look into fixing that soon. Meanwhile it'll remain disconnected, wouldn't want to waste it by accident.

Thanks for the tip regarding the programmers, Scot! I'll keep that in mind in case this one really does decide to bite the dust.

Heat is good and hot; my old friend Sergeant Pepper seems to have worked his magic once again. No longer getting sickeningly-sweet antifreeze fumes in the cabin, nor greasy fog on the windshield when testing the defroster. Knock on wood!

Fixed the front right marker and cornering lights as well; after finding power all the way to the terminal but still no lights, I was completely stumped. Turned out the problem was a bunch of crusty corrosion sandwiched between the light socket and the housing it presses into/grounds to. After some careful work with a pick and a screwdriver, I got both to make good contact and start working. For some reason the right cornering light is way brighter than the left, though. Pretty sure I replaced them both with new Sylvania 1073s I had on-hand, so maybe the left-hand cornering lamp socket could use some more cleaning up as well... Or I've just installed a brighter bulb in the right hand side than the left somehow. Not really sure how bright the cornering lights are supposed to be, though my newer daily-driver Buick has fairly bright cornering lights as I recall. Hmm.

D'oh, I forgot to get pictures during daylight, wound up being a bit more busy than I anticipated with my limited free daylight. Shorter days and all that. Got some night photos but they're grainy, mildly blurry, generally trash, as expected. Today should be the day for sure!

Scot Minesinger

You should plan to replace the heater core.  It is accessed from under dash unfortunately and it is a bit of a job replacing it.  You have to remove the upper dash pad, ducting and some braces.  Before you start blow the anti freeze out of the heater coil from under hood with compressed air, that way no anti-freeze will fall onto carpet when you remove it.  When plastic heater core housing is out of the car you can clean it up and replace any bad vacuum actuators.

The reason the cores fail is galvanic corrosion.  The copper coil pressed against ferrous metal with fluid flowing through it causes the corrosion.  The factory kept these two metals separate with paint!  When replacing it, the coil should have the protective paint, but go a step further and use gasket material between coil and all other mating metal surfaces.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Dynamic88

Yep, it's definitely on the agenda for sometime down the road, just completely out of reach for the time being unfortunately. Good call on using gasket material during installation, I'm going to put that idea to use when I get the heater core installed in my Olds as well. I figured galvanic corrosion had something to do with it, with steel braces holding the copper cores in place. Kind of reminiscent of late '70s GM cars and their prototype aluminum bumper brackets accelerating frame rust on certain unlucky cars.

Also, got some pictures, as promised. I'll admit the paint could still use a lot of finishing-up to smooth it out better, but overall I'm satisfied with it. As long as it's functional and keeps rust off the steel, I'm happy. :P
Will probably get interior shots soon, though a friend of a friend is due to re-stitch the headliner at some point for the cost of a few beers, so I might hold off until that happens. As it is, the headliner material is mostly intact, but for some reason one of the previous owners unstitched all of the seams, as if intending to remove it from the car, but never fully got around to it. ::)