1950s Power window issues

[Chavez_automotive_systems]

Ok, I'm currently helping a friend with his 1953 Cadillac power windows. They did work when he bought the vehicle but stopped working recently.i tried to troubleshoot the original wire harness but ran into a lot of improper repairs done over the years so we decided to scrap it and build a new harness following the repair manual. We installed a new circuit breaker, all new window switches, and I fabricated a new wire harness per the manual. As soon as we applied battery power, the hydraulic motor turned on but no windows would go up, they all went down no matter which way you hit the switch. Found that the driver rear switch was stuck, I removed the power wire and the switches still would not work properly. Infact they wouldn't turn the hydraulic motor on in the up position. What am I missing? Each wire was routed individually and in their own color code as not to mix anything up. Any suggestions before we just rip everything out and go to aftermarket power windows? Thank you, Jimmy

[PHIL WHYTE CLC 14192]

From memory the way the system works is quite simple, for the windows to go down the solenoid on the specific window needs to be open without the pump running and for the window to go up the solenoid on the specific window needs to be open WITH the pump running. I would guess the pump isn't running in. That would mean that the switches are not activating the pump in the up position (could be a missing live feed to the pump), or the pump is faulty. Try taking a direct live to the pump and try a window in the down position. Phil

[Jeff Rosansky CLC #28373]

I don't know that year, but is there a solonoid on the pump? That could be bad not allowing it to turn on.

[Chavez_automotive_systems]

I don't know that year, but is there a solonoid on the pump? That could be bad not allowing it to turn on.

yes, it has a trash can style solenoid. That's what I'll check tomorrow.

[tluke]

So the battery connects to the pump on the firewall through a solenoid. Coming off that solenoid (upper left corner of diagram) is the main power feed to each switch (B post -for battery) shown in red and labeled 14-16RXT - always-on power. This is the circuit that goes to the B post on each window switch. When you push the switch to raise the window, the B is connected to the M (Motor) post which is the gray (GXT) line that goes back to the what's shown as the top post on the solenoid on the pump thereby energizing the solenoid, thus allowing current to flow to the pump motor. The internals of the window switch are such that pushing the switch to UP not only allows current to the M post but also to the C (CYLinder) post which opens the cylinder inside that particular door allowing fluid to flow in either direction. When pressing UP, the pump also turns on so with the cylinder open, the fluid pushes the window up. When pressing down, the cylinder opens again, no power is sent to the pump and a spring in the window regulator pushes the window down forcing the fluid back to the pump.

That being said, if you push the window switch up and the window still goes down but you hear the motor, the door cylinder is open as it should, power is going to the pump, as it should, but if the pump was actually pumping, the window should go up. With the door cylinder open (which it is in either UP or DOWN) that means the pump is not pumping and the window goes down (BTW, how do you get the window back up?). I assume you've checked the fluid levels in the pump. You might want to flush the fluid. Originally brake fluid was used but some have been converted to power steering fluid so make sure you use the correct fluid ( certainly don't mix them)

 You mentioned that your pump was turning on until you removed the power wire to the driver's side rear switch the motor stopped turning on. That's curious. To check if the motor is getting power, one person pushes a switch up while someone else measures power at the 16GXT terminal on the relay at the pump (on the firewall). If power but no motor activity, either the solenoid or the motor is bad. If no power try jumping the 14RXT post on the solenoid very quickly to the 16GXT post on the solenoid to test the motor. If motor works, it's your wiring from the switches (16GXT) to the solenoid on the pump.

Remember, pushing the switch up should provide power to the door cylinder and the pump then does the work. Pressing it down powers just the door cylinder and the spring does the work. Pressing up with no pump working or pump not really pumping, the window goes down.
(click to enlarge)

[Chavez_automotive_systems]

Ok, so I finally got back to the 53 Cadillac. I double checked all my wires to make sure I didn't cross one, everything checked out. So I disconnected the 4 gang window switch on the driver side door, removed the connecting straps and checked all the switches with my multimeter. I found two of the switches were stuck in the on position. These are brand new switches. I checked the old 4 gang switch and it was still good. I connected the old switches and applied power to the system. The pump stayed off this time. We checked the fluid in the system and it was low, we filled it and now the entire window system works. We do have a leaking cylinder in the passenger side door, but they do work , just a little slow. I think the pump head needs to be rebuilt. I double checked all the main power wires and circuit breaker to make sure nothing was getting hot. Everything seems fine. So my harness was correct, we were just fighting a bad set of switches.thanks to everyone for their feed back. Jimmy

[59-in-pieces]

J.

What model 53 were you working on (62 or Eldo).

Did you use modern plastic insulated wires or the old fabric covered,

Where did you find the hew old switches or they modern that fit.

Have fun,
Steve B.

[tluke]

Where did you find the hew old switches or they modern that fit.

CaddyDaddy and a few other places sell reproductions. Also $300 for the driver's gang switch, $100 per single switch.

I don't think any of the newer switches will work since the switch has to accomplish two tasks with an UP push. As I wrote in my post above:
"The internals of the window switch are such that pushing the switch to UP not only allows current to the M (Motor) post but also to the C (CYLinder) post which opens the cylinder inside that particular door allowing fluid to flow in either direction. When pressing UP, the pump also turns on so with the cylinder open, the fluid pushes the window up. When pressing down, the cylinder opens again, no power is sent to the pump and a spring in the window regulator pushes the window down forcing the fluid back to the pump."

A question I have never found an answer to is how the switch sends current to both the motor and simultaneously the door cylinder. Seeing the internals to the hydro-lectric switch, I can't see how that is accomplished. I'm just curious since I don't have a pre-'54 Cadillac but does anyone know the answer?

[Roger Zimmermann]

By pushing the button "up", the wiring can be going to the cylinder and to the pump and, by pushing "down", the wiring is only going to the cylinder.
Most probably, somebody else will explain it better!

[J. Gomez]

Terry,

Just by looking over at your picture layout the logical assumption is;

The large brass spring contact label "CYL" looks to be wider than the one label "MOT". The side brass plates seem to contact the switch center brass rod.

So the brass spring "CYL" is always making contact on any directions of the switch brass either up, down, or neutral, but the brass spring for the "MOT" is open on neutral or down.

When the switch is press "UP" this will make contact with the "MOT" and the switch rod will make contact with the center pin and the brass plate (on the up side) will make contact with the side pin to power, since the "CYL" still making contact with the switch rod power will also be present on the other side pin. So power is made to both the "CYL" and "MOT" sides.

When the switch is press "DOWN" the smaller brass spring for the "MOT" remains open and power just goes to the "CYL" side in this position.

Just my observations.   

[tluke]

Aha! You're a genius!. I finally have an answer to my "Who dunnit". I first started again to seriously figure out how the window switch switches dual outputs simultaneously with a single push last year with a member's post. I've had this question since the early '70s when I tried to help a friend with a 51 Cadillac Coupe De Ville. I had just finished getting all my windows working on my '56 Series 75 so I was sure I could help him with his power window issue. I soon found out that power windows in 1951 were hydro-lectric and not fully electric like mine. We weren't successful in getting his windows to work. No internet, no shop manual, no multimeter - just a circuit tester with a light. Back then, our Cadillacs weren't vintage or classic, just old Cadillacs. So when a forum member last year asked a question about that power window system, I dug into hydro-lectric system even though I still don't own a car with those windows. (trying to redeem myself from my 1970 failure?)

Now, being a computer network systems engineer and trainer in my working life, I created a lot of diagrams of networks etc. So based on J Gomez's post, I created diagrams of how the hydro-lectric switch operates that clarifies his text for me and that I hope will help someone else troubleshoot.

As the previous post mentions and seen in the first pic, the springs are different lengths for the MOTor and CYLinder studs, the CYL being in constant contact with a brass plate used to transfer power from the BAT stud to the CYL stud while the MOT spring's gap requires pressure to connect with its brass plate. The springs not only carry current but also return the switch back to neutral position when released.

Here's how that all looks in Neutral or resting mode: (click to enlarge)


Pressure from pushing the switch forward flattens out the MOT spring so that it eliminates the gap and touches the brass plate, completing that segment of the circuit to the pump MOTor. Pushing forward simultaneous brings the stem of the switch in contact with the brass plate and current flowing from the battery through the stem flows to the pump motor.  At the same time, the bottom of the stem swivels,, like a vertical teeter-totter, in the opposite direction and makes contact with the brass plate on the CYL side and current flows to the door cylinder. Now the pumps pumping and the cylinder valve is open, the window can go up.



To close, push the switch down, the stem make contact with the brass plate on the CYLinder side, the spring is already in contact with the outside of the brass plate so current flows through the stem, brass plate and spring to the CYL stud and the hydraulic cylinder in that particular door opens, a big -tough spring inside the door pulls the window down, pushing the fluid back to the pump reservoir as the window goes down. Release the switch button and the CYL spring completes it's second function to  returns the button back to neutral position.



Mystery solved! Now it's also evident why all-electric window switches of the later 50's won't work in Hydro-lectric systems since all additional wiring external to the switch to get power to the cylinder won't work but likely will end up with all windows going up/down from all switches. Power to each individual door cylinder need to be isolated by its switch.