K5 Blazer Rear Window Issue, and an Introduction

[HankScorpio]

Its 40 years old, you will need to do some testing once you get it open. A test light will help determine if you are getting power to the motor as you press the dash button, same with the key. Look for corrosion on the connections and wiring. Check the grounds also. With the lights flickering the motor may be trying but the mechanism may need grease or some repair work. Something may be binding. The rollers and pivot points in there wear out.

 

[imiceman44]

Older thread but hope I can find some answers..
I am having issues with my rear window going up on my 1986 GMC Jimmy. This is my first one, just purchased a couple weeks ago and I am quickly learning that this has been pretty common problem for most if not all Blazer/Jimmy owners at some point.

Last night I changed out the existing motor with a new motor, the window will roll down (very slow)but still does not go up..When I hit the automatic switch on the dash in attempt to roll up the window the dome lights in the cabin dim/flicker.. I am able to easily roll the window all the way up and nearly all the way down when I hook the regulator cable to a cordless drill. The window itself rolls up and down smooth with no abnormal sounds or restrictions. I am also wondering how do I even lower the tailgate to make this work easier for me to tackle. I cannot release the latch within the inside of the tailgate to release it down. When I try to use the key on the exterior of the tailgate I can hear the motor stirring but no action.. I live in Arizona and I am 6'7" so I was pretty much dying in the back doing this work, so I need to be able to get this tailgate down at the very least.

The fact you had flickering lights when operating the window you have bad wiring.
Could be bad ground or just old thin wires that have degraded.
I would put new wires in and preferably thicker.
You could also use a kit someone here made with a relay that gets more power to the tailgate. I will try and remember who and post back here.

 

[Blue85]

There is a mechanical latch in the bottom of the tailgate that must be pressed for the tailgate opening mechanism to work. It is pressed down by the bottom of the window mechanism. That prevents you from breaking the glass.

The keyswitch inside the tailgate has a tendency to corrode over time. It can be cleaned or replaced or have the contacts replaced if you're super tricky.

The window will go much faster with the engine running, in case you're doing it otherwise. Sometimes an old motor combined with dirt or rust in the mechanism just isn't powerful enough without somebody "helping" the window with their hand.

A classic cause for the window going down but not up is the safety switch attached to the DS tailgate latch. You can pull the latch out from the side of the tailgate, take the switch apart and clean the contacts.

 

[AZ86JIMMY]

Thank you, appreciate it! I'm not knowledgeable when it comes to wiring especially and this is all learning for me. I'm not shy to try though and use resources here on this forum and watch YouTube videos.. would you think either of these two kits here are something worth considering and if so which one??

K5 Squared Rear window full power kit - K5 Squared

This is the rear window only kit from K5 Squared. **ALL KITS ARE MADE TO ORDER, SHIPMENT MAY BE DELAYED A FEW DAYS**

k5squared.com

K5 Squared full power relay - K5 Squared

Wiring harness that will help the speed of power windows in K5 Blazer, and Jimmy. Wires, fuses, relays, mounting hardware, and connectors are all included to complete this upgrade on your K5. **ALL KITS ARE MADE TO ORDER, SHIPMENT MAY BE DELAYED A FEW DAYS**

k5squared.com

 

[AZ86JIMMY]

There is a mechanical latch in the bottom of the tailgate that must be pressed for the tailgate opening mechanism to work. It is pressed down by the bottom of the window mechanism. That prevents you from breaking the glass.

The keyswitch inside the tailgate has a tendency to corrode over time. It can be cleaned or replaced or have the contacts replaced if you're super tricky.

The window will go much faster with the engine running, in case you're doing it otherwise. Sometimes an old motor combined with dirt or rust in the mechanism just isn't powerful enough without somebody "helping" the window with their hand.

A classic cause for the window going down but not up is the safety switch attached to the DS tailgate latch. You can pull the latch out from the side of the tailgate, take the switch apart and clean the contacts.

Thank you, I'll give this a shot as well, each attempt tried has been with the truck running. I found a couple of wiring kits I linked in another reply here for input as well, won't solve the latch issue though and will try your suggestions for that separately. ‍

 

[Blue85]

https://ck5.com/forums/threads/k5-squared-window-relay-kit-review.350028/

 

[rampage]

The ground for the motor goes through the hinges on the tailgate - there’s a TSB about it. If there’s any corrosion on the hinges where it mates to the tail pan then it’ll increase the resistance and make the motor run slow. Try running a 10 AWG or heavier wire (numerically lower) from the case of the window motor to the frame, both to bare shiny metal.