87 K10 Power Windows slow

[87 K20]

Hi all,

I've researched the issue of my power windows being super slow...I am getting 12V to the power window motor when in the ACC position, and 14+ when the truck is running.  The tracks seem pretty well greased, and window slides pretty easily up and down in the channels.  Please confirm that I should replace the motor, and offer any other advice if necessary.

thanks!

[AZ87V10]

I wouldn't mind knowing a positive answer to this as well. I know from my research on this site that the factory wiring harness robs a lot of power from the motors, but that can't be the only reason why they operate slowly. My windows operate correctly from both switches in the doors, they just run real slow. Now that I think about it, so do my wipers! I think somebody put an undersized alternator on my truck before I bought it.

[hatzie]

The alternator isn't the problem the battery will push 800+ amps to anything that asks for it and the 65A 10SI will catch the charge back up while you drive.  If you are seeing 14+ volts at the motor plug that's pretty much all you can ask for.
The window track rubber has flocking bonded to the rubber.  The rubber is dried out and the flocking is long gone.  You can get some relief by hitting the channels with silicone spray or clear silicone paste. 
Spray Lithium grease or Creeping Silicone grease is needed for the rollers and the pivot points.
The wipers can use the same treatment. 
Wurth HHS-K is a pretty good creeping silicone that I even use on the door and hood hinges. It sprays on thin like WD-40 and the solvent flashes off leaving the grease behind in all the nooks and crannies.
If they're still slow probably the lubrication for the motor is dried out after 35+ years.  Unfortunately they are sealed...

[bd]

You checked the motor feeds, but did you verify the ground path?  Connect your voltmeter between the negative post of the battery and the ground terminal of the motor (keeping in mind that which terminal of the motor acts as the 'ground terminal' is dependent on whether the window is raising or lowering).  With the motor energized there should be no more than 0.5 volt measured across the ground path, motor-to-battery - the closer to zero, the better.

[AZ87V10]

Hey Rich, were you asking me or the OP? I haven't actually checked the output voltage or grounds on my motors themselves. I know my truck has a brand new Optima battery in it and has a good charge. Through my research, my truck had a 94 amp alternator in it originally although someone replaced it with a 78 amp at some point before I bought the truck. I have verified that it puts out about 14.5 volts while running so it's operating correctly. The window motors and the wiper motor is getting voltage since they all operate as they should. They just run slow. I don't seem to have any other electrical problems with the truck. Besides the starter that grinds when I start the truck, but that's a separate problem altogether. All lights and accessories operate as they should. I have noticed that the voltmeter drops sometimes significantly when the truck is idling, like after I come to a stop for instance. Not sure if that's more electrical or engine related.

[frotosride]

Your problem is in the switch. They were designed to carry all the load. Unlike today's vehicles where the switch simply controls a relay which. You are receiving the right voltage but the amperage is what is not coming through due to the switch. If you purchase new switches it will speed up a small amount for a period of time but will soon fade as well. In my experience all of the new aftermarket switches are of lower quality and slow the window operation much faster. Your other option that may exceed your expectations are relays as many here have done.
To verify for your self that it is the switch simply run leads to the switch and remove the connector. Using the leads in the holes on the connector that go to the motor you will be able to manipulate the windows and rule out the switch and or the motor.

[bd]

Hey Rich, were you asking me or the OP?

I was responding to the OP to round out what had already been posted, since it is far too easy to overlook the ground path as a source of trouble.  Too often, ground is "assumed" to be zero and perfect when in fact it isn't, because of a simple connection issue.  Both power window motors share a single grounding point - hence, a poor ground will affect both motors similarly. 

Measuring only the voltage supply as the OP expressed, is testing only half the circuit.  Ground continuity needs to be verified for a complete evaluation of the electrical environment.  Else, assumptions are made that can postpone attainment of a workable solution, bringing disappointment.  After all, ground is as fundamental as power to the function of every electrical appliance.

On the other hand, when it comes to power windows in GM squarebody trucks, the factory consistently incorporated too much wire of insufficient gauge and too many connections subject to gradual oxidation.  The end result was excessive circuit resistance that only increased over time, and that proportionately limited the voltage and current available to the motors.  Ultimately, otherwise perfect motors burn out if that low voltage condition isn't corrected.  Barring excessive friction from poor lubrication and/or window adjustment, adding relays is one of the most noticeable and beneficial modifications that can be effected to correct sluggish electric window operation and extend the lifespan of window motors.

[AZ87V10]

You're absolutely right and your troubleshooting steps are always spot on and very concise. I trust what you're saying. I've noticed that the factory power window setup does seem to be lacking in reliability. I'm sure the rubber window tracks being 29 years old and dry rotted probably compounds the issue. Speaking of adding relays to the harness, I found a pre fabbed harness with relays built in to address this very issue. Do you or anyone else have any experience with these? Would it be easier to buy and install those versus home fabbing one? Cheaper?

[blazer74]

Lot of info on the net for doing the relay mod yourself.

[bd]

See the relay modification presented by frotosride in Wiring up power windows and door locks.

[AZ87V10]

I'll check it out. Thanks!

[87 K20]

Thanks for all the replies...I did check the ground at the ground bus under the dash, and they looked pretty clean...I did not do the actual voltage test on the ground, so I will check that.  As I mentioned, when I pull up on the window, there doesn't seem to be much resistance from old rubber, and the nylon bushings look to be in good shape and pretty well greased. 

[frotosride]

You're absolutely right and your troubleshooting steps are always spot on and very concise. I trust what you're saying. I've noticed that the factory power window setup does seem to be lacking in reliability. I'm sure the rubber window tracks being 29 years old and dry rotted probably compounds the issue. Speaking of adding relays to the harness, I found a pre fabbed harness with relays built in to address this very issue. Do you or anyone else have any experience with these? Would it be easier to buy and install those versus home fabbing one? Cheaper?

you will never find a premade harness that will rival DIY as far as price goes. However if you are not into soldiering and head shrinking and wiring schematics then pay the money. But if you are ambitious and have the patience to make sure you can explain what you are doing to yourself in its simplest form then go for it. it is surely time consuming.
There is one update that I have to do to that and that is soldiering a diode in for the passenger window switch.

[87 K20]

Thanks for the replies guys....I replaced the motor in the drivers side, and the windows work great now.  Having the regulator assembly out allowed me to grease everything as well.  Just have to do the passenger side window, and also troubleshoot the power door locks