I'm a truck driver so I didn't use my Blazer for a week. I came back yesterday and now there is a slew of problems. Dome light, 4x4 and temp gauge all not working.
For the Dome (Courtesy) lamp I found a blown fuse. Replaced the fuse and instantly blew. Guess I need to find the short.
4x4 has no orange indicators on the switch and there is no response to pressing the buttons (3 button) I checked the 4x4 fuse in the drivers side fuse box. Looks good, as continuity on both sides. Looking at the 4x4 wiring diagram, it seems the courtesy lamp fuse that is blown is in the 4x4 circuit. I can't tell what it does in the 4x4 circuit . Im hoping once I get my courtesy lamp circuit fixed it will start operating normal again. Anyone else have this issue?

The temp gauge didn't work the whole way home (about 30 miles). It does a test sweep at start up, so I know the gauge is working. Checked the hoses. Good temp. Checked the coolant level. Good level. I looked in Alldata but can't find the DVOM testing procedures/ specs for the sensor or the location of the gauge sensor (I know the one that reports to the pcm is on the left bank head).


UPDATE: I just went outside and pulled the dome lamp assembly and unplug it (don't know why I had the urge to do this lol). Installed a new fuse (20A even though it should only be a 10A cause that was the only thing I had, figured it would blow if there was still a short) and my map lights came on. Pushed the dome over ride and the rest of the lights turned on. Started her up and the 4x4 indicator was back. Test drove and 4x4 works again. Brought the dome lamp assembly inside to inspect it. Found corrosion buildup on the bulb and the contacts. Tells me moisture got in it. Guess my next step is to drop the headliner and look for leaks. I will replace the 20A fuse with a 10 A tomorrow) as well as the cruise control fuse I blew at first.

Still have the temp gauge problem though. Just need to know the location of the gauge temp sensor. Did come across the resistance values.

 

Another update and the end to this thread:

Woke up this morning and found the wiring diagram for the temp sensor. Why in the world is the courtesy lamp fuse in this circuit too? Went out and let the truck warm up. Temp gauge started going up.

So if anybody has these three symptoms, it is most likely all related. Really stupid, isn't it? lol