1988/89 glass quad headlights: need adjustment procedure + stuck screws

[GoToGuy]

Hmmm. Your here and nobody mentioned free here, to download PDF factory service manuals? Make life easy, work smarter...etc

 

[PlayingWithTBI]

I'm trying to avoid spending retirement money on a full manual for a truck I actually don't have

This may help, I briefly looked into my 88 manual and couldn't find anything but, I didn't dive into it excessively.

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

 

[GoToGuy]

Electrical= chassis, lighting, instruments so on. Begins at Section 8 sub part a or b lighting and headlights and aiming etc.

 

[Hipster]

Hipster, here are photos. Top is spare unit. Early stages of clean up.

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Ok not what I had pictured in my head. They're all external. Give them a good dousing over a couple days with something like wd=40, Something with some mild penetrating qualities. I'm not sure you would want to use something like pb blaster on plastic parts. Use a socket(7 or 8mm?) on the external hex instead of the internal torx to get them freed up on the ones you can. It's not difficult to chew up the torx in the screws. Be gentle.

 

[DennisT]

Downloaded PlayingWith...'s '88 service manual. Wonderful scans; not fuzzy. Found Section 8, has headlight replacement, etc., but have yet to see adjustments. Still looking.
Hipster, exactly what I'm doing. Gentle lube and taking my time with it all.

 

[GoToGuy]

For the 88 manual it might be in the Unit Repair Section. I just looked in the 95 service manual and two different procedures are listed in section 8, diagrams and specs and drawings. That will fix you up.

 

[DennisT]

GoToGuy, you're right, in the '95 manual there are headlight adjustment instructions right where you said they were..........for composites and W/T entry level truck single sealed beam lights. It does not cover 4-glass quads, probably because they were not offered that year. I searched the '88/89 manual links and downloads again and nothing. My last thought is to find, again, the glove box owner's manual. Still, .. we may not need to burn more time on this because how many adjustments can there be? Up, down, left, right. If, when I get these adjusters working, it ought to be evident how to use them. My only thought in pursuing this was to see if instructions revealed more information on the mechanisms themselves. During all this, I did save that '95 service manual pdf for my '96, as there was no link to my particular year's docs. Thanks again guys.

 

[TechNova]

Someotherguy, that's a good story. I had no idea individual adjusters were available, of any kind. Don't see any that match yet, but now I have something to look for. Meanwhile, I'm going to cautiously soak the threads, etc., on mine and see what happens. They still seem over complicated to me.

I have replaced hundreds of the straight headlight adjusters, still have a couple drawers full. Very few of the angle drive or gear drive style were available seperately. I have not seen any replacements for the 400 quad lights.

 

[DennisT]

TechNova, I think you've wrapped it up. Aveco that SomeOtherGuy mentioned, I checked. Nothing like I have, but it opened up a new world of parts I knew nothing of. Worth it just to look. So what I've chosen to play with for headlights is part of a 2 year run that was never backed up well with repair parts. I often pick the real headaches to work with. Ha. The one-and-a-half sets of light brackets I found so far are the only ones I've seen around here. This won't be done until Spring, so I'll likely find 2 or 3 more for back up by then.

 

[someotherguy]

I have replaced hundreds of the straight headlight adjusters, still have a couple drawers full. Very few of the angle drive or gear drive style were available seperately. I have not seen any replacements for the 400 quad lights.

Crud, well that sucks. I was wondering if the 3rd gen Camaros used the same headlights, so I looked 'em up.. nope. Similar. In fact the 3rd gens use the same headlights as the very last squarebody Suburbans with the 4 sealed beams (H4656 low, H4651 high) vs. the 88-89 GMT400 using H4703 low, H4701 high. To that end, I wonder if the assemblies from either of those vehicles use the same adjuster hardware, though? Not many of those Suburban setups out there but the Camaros used the quad sealed beam setup for the entire 3rd gen run - 1982-1992; that's a lot of cars.. could be useful for boneyard hunting. It's a pain to think about where to source adjusters but if you need 'em you need 'em, and if they're not available new.......

Richard