This 2001 Chevrolet Silverado LS 5.3 4WD came into the shop with a customer complaint that the driver's window would go down, but it would not go back up.
The first step was to confirm the customer's concern. When pressing the power window switch on the driver's door, we could hear clicking, but no upward movement. We discovered, as the customer said, that the window would indeed go down, but not up.
We pulled a wiring diagram and found the applicable circuits for the driver's side window motor. The green wire is the voltage supply wire with the ignition in the on or run position. Based on the clicking we heard earlier, we knew we had good voltage there. We double checked it for accuracy and it had constant voltage. The voltage was present with the switch not being activated and it was present continuously when the switch was being depressed to move the window down and up.
Below is a picture of the assembly, out of the door panel, showing the back of the switch with the wires.
This told us the supply circuit was good. We did the same checks on the black wire for the ground. It too checked good. We expected both of these findings, but wanted to perform a thorough diagnostic to be sure.
Next we checked the circuits for the up and down motion of the driver's window. The two wires that operate the driver's side window are the blue and brown wires. The two wires should show ground with key in the on or run position.
The blue wire (see below) should have battery voltage (B+) on it when rolling the window up and it should show ground when rolling the window down. The brown wire is the opposite: it should have voltage when rolling the window down and be grounded when rolling it up. (Basically, the two wires simply complete the circuit, one way or the other.)
The blue wire then could be thought of as the "Up" wire and the brown as the "Down" wire. In fact, this is how it is labeled in the schematic.
The blue wire should have voltage on it when the switch is depressed to send the window up and the brown wire should go to ground. The brown wire should have voltage on it when the switch is depressed to send the window down and the blue wire should go to ground.
The brown wire checked good for voltage when depressing the switch to roll down the window. The blue wire should have ground on it to complete the circuit: it did. Again, these findings were expected since the window would roll down with no problems.
Below is the blue wire showing ground when rolling the window down. This is good.
When we checked the circuitry for rolling the window up, we found the problem. The blue wire had voltage on it, as it should, when depressing the switch to roll the window up. However, the brown wire, which should be grounded in this case, to complete the circuit, was not grounded. Sometimes it showed no life at all (meaning it did not have voltage or ground); and other times, it showed to have constant voltage.
Below shows an instance when the brown wire showed no life at all, when trying to roll the window up. (Again, we rolling the window up, the brown wire should be grounded to complete the circuit.)
Below shows an instance when the brown wire showed voltage while trying to roll the window up. (Again, in order for the circuit to work, it must be grounded.)
This evidence told us that the motor and regulator were good. The problem was the switch. We replaced the Driver's Power Window Switch and the window went up and down as it should. (To replace the switch, there are two retainers that must be popped up and the assembly will lift out of the door panel. Then, on the back, there are two Torx bit fasteners, T-15s, to remove and the switch will come out of the assembly. To install, just reverse the steps.)
Below are a couple of pictures of the switch.
We tested it several times and then shipped the vehicle.