Sluggish power window on passenger side.

I am new here so please bear with me. I will try to keep this as short as possible and still provide enough detail. I recently decided to convert the manual crank windows in my 2004 Chevy Silverado to a power system. After much research, I decided the best approach would be to purchase OEM replacement regulators from ACDelco and control them with a Spal 2-Door switch kit (#33040188) using three switches. Here is switch the diagram from the Spal web site: While troubleshooting, I discovered two issues with this diagram which I should point out here. First; the blue/black wire reference on the bottom left (driver side) should say PURPLE / black. Second; the diagram on the right (passenger side), if you look at it the same way as the switches on the left, shows the MOTOR connected to red and blue/red when it should be connected to the two PURPLE / black wires. Again, it depends on how you view the connector. I just wanted to explain those two issues because they have been resolved. After getting the connectors right, I wanted to test the system. So I temporarily connected the brown ground wire from the Spal switch wiring harness to a bare metal screw on the vehicle chassis. Then I ran a #12 AWG stranded copper wire directly to the positive terminal of the vehicle battery. With the ground wire connected, and the in-line fuse attached, I then touched the red “power in” wire from the switches wiring harness to the constant +12V supply from the battery. The result was that the driver side window ran up and down normally and at a “good clip.” However, the passenger side window was/ is extremely “sluggish” when going up (it goes down fine). This is the case with either the left or right passenger side switch. I did this test with the vehicle off. The situation does improve with the engine running, but the passenger side is still slower than the driver side. I also “greased” up the window channel with silicone paste which made a slight improvement. I phoned Spal tech support and explained what was happening. The technician said that it is probably an issue with voltage drop and that I needed to install a SPDT relay (per the inset box in the diagram). First I went out and checked the voltage at each of the three switches and got the same +12.5 volt reading all around. So right away I was skeptical, but not being that familiar with relays, I spent some time researching to get a better understanding of how they worked and what I might accomplish by adding one to this circuit. Perhaps I am not fully understanding but ultimately I am not seeing how a relay could help with the sluggish passenger window issue. So I would greatly appreciate any input on what might be going on here and how I might remedy the situation. I will add that, with the engine running, I can live with the slower window on the passenger side, I just want to make sure that I am not damaging the motor or switches in any way by using it like it is. Thanks in advance for any comments, advice, guidance you can offer.

Nasty but you will either have channel mods or that motor is "soft". I think it's the channels. Remove the Delco motor and see how freely the glass raises when you use your hands. If very stiff, please note that on most vehicles the mechanical part, the regulator, it's fixings can be adjusted. Try that until it runs smoothly then try again with the Delco motor reattached and wired. Greasing actually clogs even more, most regulator moving parts are sealed, non silicon sprays are best but the all dry out after a time. Brittle, aged rubbers are also a problem.

howie ll wrote: Nasty but you will either have channel mods or that motor is "soft". I think it's the channels. Remove the Delco motor and see how freely the glass raises when you use your hands. If very stiff, please note that on most vehicles the mechanical part, the regulator, it's fixings can be adjusted. Try that until it runs smoothly then try again with the Delco motor reattached and wired. Greasing actually clogs even more, most regulator moving parts are sealed, non silicon sprays are best but the all dry out after a time. Brittle, aged rubbers are also a problem.

Good info thanks again. So do you agree with me that a relay is not going to help with one sluggish window? I used the silicone paste to recondition the rubber in the channels and try make it "more slippery." I'll try unclamping the window like you said to see if it goes up and down freely on its own. If it does (move freely) I may return the motor as defective. I bought the two new regulators from Amazon so getting a replacement won't be a problem.

You have it right now try it.