I am moving this discussion about window control to a new thread, so it does not mess up @rsporsche's thread about fog lamps.
There have been a number of posts and discussions about improving the power windows. Some of these have to do with simply getting the window mechanisms to operate properly (alignment, lubrication, etc.)
Others have discussed various alternatives to the wiring. I am going to assume here that we are talking about three wire motors. If not, many of the same ideas that are likely to be expressed here can be modified to support 2 wire motors. The difference here being that two wire motors require current to reverse direction to make the motor go from up to down. Three wire motors have two opposing windings, so powering one winding makes the motor turn one way, and powering the other makes it go the other way.
The baseline system uses a single pole double throw window switch. The common pole is tied to fused battery power. One of the switched poles goes to one motor winding, and the other goes to the other winding. Move the switch one way and the window goes up. Move it the other way and it goes down.
This basic system works, but it is not really very ideal. First issue is that the switches must carry the full current of the motor, which is 10-15 amps, until the motor stalls, at which time it may peak at much more unless a fuse blows. This not only creates resistance, but it also affects the long term reliability of the window switches. The second problem is that there is a lot of wire between the battery and the window motor (battery to the fuses, fuses to the console switches, from the console switches back through the instrument panel and out through the door hinge to the motor). Both of these conspire to increase the resistance of the circuit, and thereby reduce the torque of the motor. Resulting in slow window movement.
One alternative I have seen discussed a lot is using relays in the doors to power the windows. In this setup the window switch controls one of two relays for each window. The relays take raw power from the fused circuit, and based on lower current signals from the window switch, the relays either power one motor winding or the other. This is a good system since the higher power is controlled by the larger relay contacts, and the wire run is more direct, from the fuse to the relay and to the motor.
The downside of this is that it takes eight relays. One for up and one for down for each of four windows. And, these relayer fairly bulky and hard to install in the door, which is the optimal electrical location.
I have been noodling on various alternatives to this approach. The first is to use power MOSFET transistors instead of relays. This is much simpler and more compact, because the transistors are small, and simpler to control than a relay. Conceptually the approach is the same, but this approach results in a smaller assembly that is easier to mount inside the door. the other advantage is that the window switches use "negative logic" which means they simply ground the control wire, so there is no need to battery power to the switches at all. Here is a circuit diagram for this:
There have been a number of posts and discussions about improving the power windows. Some of these have to do with simply getting the window mechanisms to operate properly (alignment, lubrication, etc.)
Others have discussed various alternatives to the wiring. I am going to assume here that we are talking about three wire motors. If not, many of the same ideas that are likely to be expressed here can be modified to support 2 wire motors. The difference here being that two wire motors require current to reverse direction to make the motor go from up to down. Three wire motors have two opposing windings, so powering one winding makes the motor turn one way, and powering the other makes it go the other way.
The baseline system uses a single pole double throw window switch. The common pole is tied to fused battery power. One of the switched poles goes to one motor winding, and the other goes to the other winding. Move the switch one way and the window goes up. Move it the other way and it goes down.
This basic system works, but it is not really very ideal. First issue is that the switches must carry the full current of the motor, which is 10-15 amps, until the motor stalls, at which time it may peak at much more unless a fuse blows. This not only creates resistance, but it also affects the long term reliability of the window switches. The second problem is that there is a lot of wire between the battery and the window motor (battery to the fuses, fuses to the console switches, from the console switches back through the instrument panel and out through the door hinge to the motor). Both of these conspire to increase the resistance of the circuit, and thereby reduce the torque of the motor. Resulting in slow window movement.
One alternative I have seen discussed a lot is using relays in the doors to power the windows. In this setup the window switch controls one of two relays for each window. The relays take raw power from the fused circuit, and based on lower current signals from the window switch, the relays either power one motor winding or the other. This is a good system since the higher power is controlled by the larger relay contacts, and the wire run is more direct, from the fuse to the relay and to the motor.
The downside of this is that it takes eight relays. One for up and one for down for each of four windows. And, these relayer fairly bulky and hard to install in the door, which is the optimal electrical location.
I have been noodling on various alternatives to this approach. The first is to use power MOSFET transistors instead of relays. This is much simpler and more compact, because the transistors are small, and simpler to control than a relay. Conceptually the approach is the same, but this approach results in a smaller assembly that is easier to mount inside the door. the other advantage is that the window switches use "negative logic" which means they simply ground the control wire, so there is no need to battery power to the switches at all. Here is a circuit diagram for this:
Last edited:
