Re: 56 400 coupe window problem
Posted by HH56 On 2023/8/13 10:00:24
Power windows can be kind of an issue particularly with large glass in 2 door models. Due to the lack of a significant mechanical advantage in the mechanical portions of the door and quarter window regulators, the motors are working at near maximum capacity when raising the heavy door and quarter glass. On the long doors, there is also a twisting action between the motor section and the section that actually raises the glass. That twisting can flex the inner metal door panel resulting in cracks in the metal where the glass raising section bolts to the door.
Since the entire system has not failed, the relay is not the issue. All that does is provide power thru a circuit breaker to the window circuit when the key is turned on. There is a thermal breaker in each motor, but for that to trip, the motor would need to be fairly hot. If there is a mechanical bind and the motor is really straining it is a possibility though. The motors themselves can fail and a typical failure is the shaft breaks inside the motor as the window stops abruptly in the up or down position. Doubt that would have happened on so many motors so another likely issue is the switches.
Except for the drivers door, there are two switches that can work each window. If only one switch fails to move the window but the other does then most likely a bad switch or a connection. If both fail, motor, a loose connection to the motor, or a broken wire is more likely.
The wire connections to the switches are made by a small terminal block that is just pushed onto the pins coming out of the switch. There is no mechanical means to keep it in place so it can be pulled loose by vibration and weight of the wires. The terminals inside the strip can also become loose or corrode, both resultig in a poor connection. Worst case is the switch itself has failed. All the current supplied to the motor goes thru a relatively small contact area in the switch. The heavy current required when the window hits a stop and the brief period motor can no longer move before switch is released can burn the small contact area over time until it finally reaches a point enough has been burned off the connection cannot be made. That almost sounds like what has happened on at least one switch. There are no repair pieces so if you have a bad switch the only solution is find another. You can bypass the switch to test the motor by making a small jumper from decent size wire and insert it into the holes in the terminal block to mimic the switch. From the center hole to either of the outside holes will make the motor move the window up or down.
I would suggest taking the upholstery panels off to get to the switch and mechanical pieces and make sure the terminal is securely on the switch. It will be difficult to do much lubrication but you might try getting some water resistant grease on the slider tracks at the bottom of the glass to take as much stress as possible off the motor. Also check for cracks at the top center portion of the door.
Here is the wiring diagram for the window circuit. This is the 55 drawing and is identical wire wise to 56. I posted this one because it does not show all the extra sedan door lock circuitry which your hardtop does not have and would tend to confuse the issue. The motors are all the same. There are two wires feeding each motor. The motor case is ground and only ONE of the motor wires gets power at a time. Voltage on one wire makes window go up, voltage on the other wire makes it go down.
Attach file:
window.jpg (176.05 KB)
Since the entire system has not failed, the relay is not the issue. All that does is provide power thru a circuit breaker to the window circuit when the key is turned on. There is a thermal breaker in each motor, but for that to trip, the motor would need to be fairly hot. If there is a mechanical bind and the motor is really straining it is a possibility though. The motors themselves can fail and a typical failure is the shaft breaks inside the motor as the window stops abruptly in the up or down position. Doubt that would have happened on so many motors so another likely issue is the switches.
Except for the drivers door, there are two switches that can work each window. If only one switch fails to move the window but the other does then most likely a bad switch or a connection. If both fail, motor, a loose connection to the motor, or a broken wire is more likely.
The wire connections to the switches are made by a small terminal block that is just pushed onto the pins coming out of the switch. There is no mechanical means to keep it in place so it can be pulled loose by vibration and weight of the wires. The terminals inside the strip can also become loose or corrode, both resultig in a poor connection. Worst case is the switch itself has failed. All the current supplied to the motor goes thru a relatively small contact area in the switch. The heavy current required when the window hits a stop and the brief period motor can no longer move before switch is released can burn the small contact area over time until it finally reaches a point enough has been burned off the connection cannot be made. That almost sounds like what has happened on at least one switch. There are no repair pieces so if you have a bad switch the only solution is find another. You can bypass the switch to test the motor by making a small jumper from decent size wire and insert it into the holes in the terminal block to mimic the switch. From the center hole to either of the outside holes will make the motor move the window up or down.
I would suggest taking the upholstery panels off to get to the switch and mechanical pieces and make sure the terminal is securely on the switch. It will be difficult to do much lubrication but you might try getting some water resistant grease on the slider tracks at the bottom of the glass to take as much stress as possible off the motor. Also check for cracks at the top center portion of the door.
Here is the wiring diagram for the window circuit. This is the 55 drawing and is identical wire wise to 56. I posted this one because it does not show all the extra sedan door lock circuitry which your hardtop does not have and would tend to confuse the issue. The motors are all the same. There are two wires feeding each motor. The motor case is ground and only ONE of the motor wires gets power at a time. Voltage on one wire makes window go up, voltage on the other wire makes it go down.
Attach file:
window.jpg (176.05 KB)
This Post was from: https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?post_id=260322