Full Size K5 (1969-1991) GMT415 (1992-1994) Tech Discuss any and all full size K5 general tech topics here.

1989 Blazer end gate issues

  #1  
Old 03-14-2019, 08:20 AM
New Member
Thread Starter
Join Date: Mar 2019
Posts: 3
Josh Yates is on a distinguished road
Default 1989 Blazer end gate issues



Part 106 in the picture. Block out switch
I have a 1989 Blazer and the electric rear window wonít go up. I checked the fuses, not it. I changed the motor, not it. I replaced the dash switch, not it. The cable is new. The electric window functioned great, but yesterday it just quit working (wonít go back up). So now Iím down to the block out ďsafetyĒ switch. Part 106 in the picture. I pulled it out, cleaned up the terminals and put it back in. Didnít work. Can I bypass the switch by jumping it with a wire? Maybe jam a 30 amp fuse in it and tape it up to protect against moisture?

Im really at a loss. Any advice?
 
  #2  
Old 03-14-2019, 09:06 AM
cleburne red's Avatar
BF Veteran
Join Date: Sep 2011
Location: Texas
Posts: 2,270
cleburne red will become famous soon enough
Default

I don't know how that window works specifically, but that safety switch is most likely normally closed, and opens up to prevent the window from operating. Maybe buzz it with a meter, see what position it's in? If open, I would try to jumper around it, see what happens.

Also, have you checked voltage at the motor while someone operated the dash switch?

Again, I don't know anything about first gen​​​​ K5 (?) rear windows, but I've got a pretty good understanding of basic electrical theory
 

Last edited by cleburne red; 03-14-2019 at 10:24 AM.
  #3  
Old 03-14-2019, 09:27 AM
swartlkk's Avatar
Administrator
Join Date: May 2005
Location: Waterloo, NY
Posts: 40,803
swartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond repute
Default

The switch is only there to remove the possibility of the glass moving up into the closed position with the gate down. It functions like cleburne red described it by completing the circuit when the gate is closed and opening it when the gate is down. It is VERY simplistic and easy to check with a multimeter set to test continuity. Should have near zero resistance when the switch is closed and should read open when the switch is open.

As far as bypassing it, yes it can be bypassed either by using a jumper across the connector or by cutting the connector off and using a butt connector to complete the circuit. Many people have done exactly that over the years with these trucks in attempt to get the power rear window working again. Most skip over the actual electrical troubleshooting steps and jump right into replacing parts like you as well.

My '74 has a manual regulator into it now, but I have a power regulator that I plan on putting into one of my rust free gates when I get some time. When I do that, I am completely redesigning the circuit to include relays back at the gate to control +12V to the motor. I will also be installing a good ground to the inside of the gate as well since this is a major concern with the older gates. Without pulling up a wiring diagram for the newer ones, I can't say for sure if they ever remedied the issue of ground being transmitted through the hinges as it was in the older ones.

Let me see if I can find a wiring diagram specific to your truck.

*EDIT* - So here's what I could find that should match up with your truck. It came out of the 88 R/V (K5 Blazer & Suburban) wiring manual that I have, but it should show you where you need to be testing and for what. It does look like they did add a dedicated ground to the gate, but you should test for good continuity to the body and/or directly to the battery negative post. From there, you need to see if you have +12V when one of the switches is activated. The light blue wire should have +12V when the switch is moved to the UP position and the tan with white stripe should have +12V when the switch is in the down position. As the schematic shows, the light blue wire goes through the cut-out switch to prevent the window from going up when the gate is open.
 
  #4  
Old 03-15-2019, 07:52 AM
New Member
Thread Starter
Join Date: Mar 2019
Posts: 3
Josh Yates is on a distinguished road
Default

Thank you sounds lik it's time for the multimeter.
 
  #5  
Old 03-15-2019, 08:02 AM
New Member
Thread Starter
Join Date: Mar 2019
Posts: 3
Josh Yates is on a distinguished road
Default

Thank you. Electrical freaks me out. I'm always worried that I'm going to burn something up. I'll grab a multimeter and get after it. The diagram will help. I appreciate it. One more question, if I jump it will I then have a constant draw on my battery or will my dash switch now complete/cut off the circuit? I'm sorry in advance for the novice electrical questions...Really just want to get this sorted out. Cold rides to school for my daughter and I until I do.
 
  #6  
Old 03-15-2019, 09:32 AM
cleburne red's Avatar
BF Veteran
Join Date: Sep 2011
Location: Texas
Posts: 2,270
cleburne red will become famous soon enough
Default

It shouldn't be a drain on your battery. The dash switch would still need to be operated in order for the swtich to be completed, the safety switch being jumpered would just allow the circuit to be completed in its entirety.
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
AHGilmore
Lighting & Electrical
0
12-29-2016 12:54 PM
ussexplorer
1st Gen S-series (1983-1994) Tech
2
04-11-2010 06:53 PM
89Blazer
Paint, Body, & Interior
0
07-09-2009 07:36 PM


Thread Tools
Search this Thread
Quick Reply: 1989 Blazer end gate issues


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.