I have a 1996 4wd 4 door Blazer. For the past week there was a major drain on my battery. I found a fuse diagram ( 1996 Chevy Blazer Fuse Diagram ) and was able to find the problem. Here's the weird thing, fuse 2 was the one causing the drain, so I checked everything on fuse 2-CTSY, and nothing on it was causing the drain. Then I realized Fuse 2-CTSY and fuse 23-ILIUM both had the information display center on them. So after lots of confusion, I found that the rear defogger on fuse 23-ILIUM was causing the drain. This was confirmed by disconnecting the rear defogger and leaving all the fuses in over night, and my Blazer is starting with no problem now.

My question is, where do I go from here. How do I pin point what was causing the rear defogger to stay on? I've read a few things saying it could be a bad relay or module. I'm not the greatest at figuring these things out. Any advice would be appreciated.

Here is a wiring diagram if it helps. Thanks

96 Blazer All Wiring Diagrams

 

The ILLUM fuse does not actually power anything other than the back lighting bulb in the defrost switch. Unless something is screwed up inside the switch itself, there should be no physical connection between the defroster grid and the ILLUM fuse. So if you have a draw across the ILLUM fuse and it goes away when you disconnect the defrost grid in back, then the switch is really your only source for the problem.

 

Sorry I should have explained better. The ILIUM fuse was never actually the problem. It was the CTSY fuse causing the drain (when I took this fuse out, the drain would stop). But when I found the Information display center was also on the ILIUM fuse (and CTSY fuse), I started to look at things on the ILIUM. So I don't know if there was a problem in CTSY fuse because it's some how linked with the ILIUM. The switch I disconnected was the one in the front and there hasn't been a drain since. I know this might sound crazy, but I've eliminated everything else. This is whats definitely causing the drain.
Google Image Result for http://www.dragtimes.com/images-classifieds-large/95-S-10-Blazer-headlight,-rear-defrost,-wiper-and-hatch-for-sale_220547371984.jpg Thats not my picture, I disconnected this switch http://www.google.com/imgres?imgurl=...1t:429,r:2,s:0.

Also, when I bought the car about a month ago, the CTSY fuse was blown, and the replacement fuse was already in the fuse box. I wondered why the previous owner didn't put it in, now I know why. But now that I've found the drain, what do I do from here. Thanks

 

You have the wiring diagram for the rear defrost system. Time to get out the multimeter and test the connections.

 

any solution to this problem. every time i use the defrost my battery indicator drops and if its in gear at a light it will make everything dim i checked the alternator it seems fine and battery is holding 12.4 volts when trucks off

 

scottl1346, I think your problem is different than the one in this thread. I believe that the OP had a problem with the defrost circuit draining the battery when the truck was off. Your problem sounds like your alternator is not producing enough amperage to sustain all of the current load in the vehicle when the rear defroster is turned on. Does it do this any other time? What other electrical components are on (lights, etc.)?

 

Yup! Alternator...

 

tested it by disconnecting the battery car ran off it no dimming of lights nothing. so i think its just at idle it doesn't produce enough to keep up if everything is running heat windshield wipers defroster radio ect. i only noticed it was doing this when i cam to a red light and everything was running then went dim but i think everything is fine.