Hello. I recently bought a 1988 Blazer and THE driver side power window doesnt work. Checked the fuses and somebody seem to havet messed upp the wiring. I have no power in the connectors. Powerlocks next to it work and have power. Does anyone have schematics?

 

Here is a copy of the FSM wiring schematic for the power windows. I had enough time this morning to find this for you, but have to get to work. Hopefully you are able to figure it out from here. If not, I'll try to take a deeper look at it later this evening.

 

Thank you so much! Connected the motor cables directly to the car battery and only heard a click, think i need new motor..

 

The wiring diagram posted above is from the wrong section. He has a 1988 Blazer which is a V truck (V-10, specifically). This would be in Section D of the wiring manual, not section A. The power window wiring diagram for the 2-door blazer is Section D - Page 72 that I've uploaded below. For 4-door blazers suburbans, the diagram is on the next page, Section D - Page 73.

 

While you are be correct on the section since the one I posted was the first I found in the '88 wiring manual I have which was for the C/K pickups, there is very little difference between the two diagrams and in the end the OP fixed his issue a just a few years ago now.

The 4-door chassis variant being displayed in pg 73 was the Suburban in the R/V chassis designation, and not "4-door blazers" as this did not exist in the fullsize lineup. Also, there is not enough information to say to for certain say that his truck is a "V-10" as the OP did not indicate the drivetrain of the truck, but that has less of a bearing on the topic at hand.

Fun fact about this divergence in nomenclature. The R/V chassis variants came about in 1987 as GM knew that the new body style 1/2 ton trucks were going to be released and needed to differentiate them from the older squarebody models. The 3/4 & 1 ton pickups kept with the C/K designation until the end of the square body lineup in the 1991 model year. 1991 was the last year for the R/V Blazer, Suburban, and other variants using this chassis designation as well. C&R were the 2wd variants and K&V were the 4wd variants with the 10, 20, 30 being 1/2, 3/4, and 1 ton respectively. Although somewhere between 1988 and 1989, the pickups moved to what stands today as 1500, 2500, and 3500 for the 1/2, 3/4, and 1 ton designations.

 

The wiring order in the window switches is completely different between these two diagrams. I followed yours first and ended up rewiring my switch to follow your diagram. Then when I suspected it was wrong, searched for an FSM download and discovered that the blazer was on a different wiring diagram, I had to undo everything I did and wire it back up the way it was. No other Google search results pop up for “1988 Blazer power window wiring diagram”. I just don’t want someone else to see your diagram and do what I did. I honestly didn’t think you would see this after how old the post is. I want to throw in that I appreciate you looking for the diagram for this guy before you had to go to work 5 years ago and I understand how you just grabbed the first diagram in the manual that looked right (under the K designation) considering that the guy referred to his 1988 blazer as a K5. I would have done the same thing and seeing how everyone is selling these replacement switch connectors as fitting all of GM big trucks within a ten year time span, I also would have assumed the wiring is the same for all of them. I’m not a Blazer guy, just working on my friend’s truck, so it’s been annoying having to learn these nuances like the designation switch between K5 and V10 in 1987 even though everyone still calls these K5’s well into the 90’s and the fact that the different body types are all wired differently even in the same year for no reason.

Okay, gotcha.

From what I’ve been able to gather in the last two days, the 1988 Blazers came in the popular 350, a 305 V8, and a diesel 6.2L. V10 doesn’t refer to all of these?

 

Ah I see that now. Sorry about that. The layout at the switche connectors is actually different. I was looking at the circuit designations in/out from the motor & switch sections and at the zoom level I was using I could not really tell the numbers were different on the switch bodies... That is so contrary to how manufacturing should work as well... Good catch!

Chassis designation and engine usage are not tied together in that way.

Chevrolet Blazer (1988) - Auto Catalog Archive <--- Link to a PDF copy of the 1988 Blazer brochure. Reading that, there was only a 4wd option available in '88 with the only two engine options being the 350v8 and the diesel. Digging into the only 4wd being available...the 2wd model was only offered in the fullsize Blazer/Jimmy from 1970 until 1982. On the motor side of things, it looks like the 305v8 was the standard motor in 1987 gas models, but was dropped in 1988 making the 350v8 the only gas motor available.

Interestingly enough, the "K5" came about because the 1969 model Blazer was only offered in 4wd. To differentiate the chassis from the K10 pickups and likely due to the shortened wheelbase required, the K5 chassis designation was created and subsequently used in the model name. Who knew it would become so iconic.

 

Ah that’s really interesting about the K5 designation originating from the Blazer alone. And good to know about the only models offered in 1988.

Sorry we veered off topic a bit. In the interest of not hijacking this thread, maybe you can help me with my power window problem. I have a question specifically about the window switches and how they’re wired. I’m going to refer to my section D diagram from here so I’d suggest having it open to reference. I cannot for the life of me understand the window switch portions of that diagram. My question is, is there supposed to be continuity between the tan wire and the Dark Blue/w White stripe wire inside the switches alone?

My situation: I can get the left hand master window switch to control both windows up and down just fine. The right hand window switch only rolls the right window up but not down.

I’ve ran continuity checks on the wires and these are my findings:

1. There is no continuity between the dark blue/white wire and tan wire between and up to the left and right hand switches.
2. When the DK BLU/WH wire and Tan wire are unplugged from the left switch and connected to right hand switch, there is continuity between these two wires in the right hand switch’s neutral position and no continuity between these two wires in its up or down positions.
3. When DK BLU/WH wire and Tan wire are unplugged from the right hand switch and connected to the left hand switch, there is continuity in all three left hand switch positions for the right hand window. Neutral and up positions have 5-10 ohms of resistance. There is no resistance in the down position.

Is all of this the way it’s supposed to be?

 

I have tried to build a logic table from the two diagrams as the circuit numbers are the same and the diagram I posted shows the switch states, but there are several errors in the diagram that I posted that would prohibit proper operation. I am working through getting the switch states corrected and I will post it once I get it done.

*Edit* - So here is what I have. I hope this makes sense. Basically, I'm looking at this in terms of the motor leads on the passenger side; '666' & '667'. Then looking at what happens to these leads as the different switches are moved from the neutral position to either UP or DOWN. This should give you something to follow through with your diagnosis. Rather than run through continuity checks, I would back probe the motor leads and test for power & ground at the motor leads and how things change from the various switch positions and how the changes relate to the table below.

I'm out of time for tonight to read into the wire colors and your results though. Feel free to post up your results or any other questions you might have.

Basically all of the switch state diagrams had the incorrect layout to all of the switches in terms of which pin was which circuit. I changed the center pin in the layout to '76' in all cases and the lower pin of the passenger switch to '167' and the lower pin of both switches on the driver side to '150'. This made everything work correctly or I assume it would... I tried looking at other diagrams for other years and none of them showed the switch state in this manner which is crucial to diagnosis of this type of system. If you find any errors, please let me know and I will correct it so this can be a lasting reference!

 

Wonderful. Thank you for correcting this. I hope this will help Blazer owners for years to come. I ended up just replacing both switches. I tested my switches against the new ones right at the NAPA counter for 20 minutes. The new and old passenger window switches only differed in resistance where in one or two switch positions, the new switch had more resistance. Even though my old driver window switch operated both windows just fine, I discovered a discrepancy between the new and old driver window switches. One of the switches had continuity in one of the switch positions where the other switch did not have continuity in the same position. I had a lot more positions to test on both switches but I just decided to stop there and buy the two new ones. Both of my power window switches operate my windows just fine now.