I stumbled upon the video showing how to repair a 4x4 switch unit by resoldering the cracked solder joints on the board.

In my 2000 Blazer only the 2HI lights were working though it was properly switching to 4HI and 4LO.

So I pulled my 3 position switch out and found most of the solder joints were indeed cracked. After resoldering the lights not only worked but were much brighter. I also cleaned the switch contacts with a clean pencil eraser.

An alternative to this repair is just replacing the switch assembly, $35-50 new.

Here's the video -


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A few pics of my switch circuit board -

A closeup- hard to see but the some of the round solder joints are cracked -



A view of the entire board - I cleaned up those 3 round switch contacts with the pencil eraser -

 

Good to know, man! Always nice to be able to repair than replace.

The tabs that held the two halves together on mine were busted, so I replaced the whole switch with aftermarket rockers