I originally thought my BCM had gone bad and bought one that matched mine on eBay but after tech programed it I found out it was a Fuse Box issue. It was doing strange things and all were BCM controlled. The wipers would come on when key was turned to on position and it would not start until I turned wipers off using the light switch on dash left of steering wheel. When it started you could not turn headlights on or it would kill the engine , however I could turn fog lights on and that's how I drove it at night for three months. You also could not turn wipers on or it would also kill engine. When you turned key off to end your ride the wipers would come on again even if you took key out so I had to put key back in and to on position and turn light switch to off again. After tech told me he found corrosion in fuse box I decided to pull the 25 amp fuse for the wipers and sure enough the wipers came on with key in on position . I took the fuse box apart and cleaned all of it , which a chore . I put fuse box back in which another chore in itself. It started right up and everything worked normal except my HVAC fan . After driving it about 30 minutes it stalled . I went to start it back up and nothing , it would not even crank motor over and my gas gauge had dropped to empty , I had over half tank I just put in on my drive. It put up messages on DIC saying Low Fuel ,,Traction failure and other things . After messing with it for 30 minutes it suddenly started and fuel gauge back to 3/4 tank. I drove back toward home and stopped and it stalled again with it in park idling.. This time it did not start again and I had to get Uber ride home . The next day I drive my truck to Hummer and it starts right up and I drive it home. When it stalls the gauge goes to empty and when the gauge comes up it will start. I checked at fuse with multimeter with key on and no power to that fuse and of coarse I can hear that the fuel pump is not priming but the not turning motor over at all is confusing . It has new battery and the lights and wipers and everything are powered with plenty of juice. It's like a switch was turned off and power denied to pump and starter at same time. Any ideas on this?

 

Welcome to HF.

You posted in the WRONG section (HF Help and Suggestion section says Not for any Vehicle question, but for how to use the forum features only). Anyways......

I moved this to the H3 Section where all H3 tech questions go.

More info needed. Do you have a sunroof? If so, has the passenger side floor ever been wet? If so, do the fix for clogged sunroof drains ASAP so as not to toast your replacement BCM and its harness as well as the TCCM.

Are you still trying to use the crappy azzed OEM Battery Terminal Connectors? If so, hack them off immediately and replace with a quality aftermarket set like Stingers or your favorite brand. Look that up, that causes a bunch of Gremlins and a known common failure point. First mod to be done to every H3/H3T.

Next, you cleaned the fuse box, but did you put it back together (fuse block on lower tray harness connectors) correctly? It is not a push down the fuse block on top of the tray and harnesses, that will almost always never work and you get more electrical problems or spotty power to some items, not the entire truck harness. The block must NOT be pushed down into the tray until you pull the harness connectors out and push/snap them into the bottom of the block carefully making sure all pins are straight into their corresponding slots BEFORE you put the block back down on the tray. Bend or break a pin, then the can of worms is out.

 

Sorry about submitting in wrong place and thanks for moving it. Yes I had put new and better terminals on it way back . I am very familiar now with the tray and harness plugs on fuse box and since I posted this I have popped the top tray off again and reinserted the plugs . I had to do it different as the pins on back of tray that release the locked plugs as you drop tray in are broken . After carefully locking the two plugs into the top tray first I carefully guided it into the locking part below until it clicked them in . This time I had no issues and have run the engine for two days . The only thing that is not working now is the fan for HVAC. The AC clutch kicks on like it should and I can feel heat trickling out when I turn it to heat , all blend doors are operating. I disconnected battery for 20 minutes to let the HVAC recalibrate when battery was put back on, but even though it went thru the flashing of all three lights on ***** and heard the blend doors adjusting I still have no fan . I have checked fuses and relay on passenger side kick plate and they are good . I did test relay by putting power to 85 and 86 them used multimeter to check resistance between 30 and 87 on relay and had zero resistance. I also checked the fan resister and found no sign of it being bad , no burnt spots and looks like new. As far as water getting in thru sunroof there is no sign of that at all. The fan was working perfectly until I changed blend door way back when only issue was it was stuck on heat and would not switch to AC so I checked that blend door and sure enough it was not moving. After putting new blend door the fan only came back on two times and I flipped thru all speeds and it worked fine .The next day it did not come on at all. Thought it was BCM but tech ruled that out saying fuse box was most likely the culprit. Everything but fan has returned to normal after pulling fuse box and separating all five of the tan layers and cleaning all five of those grids. I know fan motor is good and I do have another HVAC module I could put in but don't think that is issue as it has come on and worked twice with this module but I will go ahead and put other one in just to be sure. Any ideas would be welcome Thanks

 

Have you considered that it still could be the resistor? Mine died at the end of January and I remember pulling it out to attempt to clean it first and thinking that it didn't really look that bad. Didn't look brand new but I didn't see a significant failure anywhere. Just went to the garage to check but I didn't keep the old resistor so unfortunately no pics. Grabbed this on Amazon for $12 and now everything works perfectly. If you aren't 100% sure about the resistor functionality and have only determined its quality based on visual inspection, I would consider spending the $12 and getting a new resistor. If it doesn't solve your problems then at least you have addressed a likely looming issue, assuming it has not previously been changed.

The same time my resistor went out, I was also replacing a hydraulic brake hose. The brake bleeding procedure requires you to turn the ignition on and off at least four times. I had issues at first and cycled the ignition on and off probably 8 times before I got everything bled correctly. It was the very next morning when I recognized I had no heat coming out of my vents which then led to the resistor replacement. Seems like you've been messing around with the electricals quite a bit from your post so it's possible that something happened to the resistor. I also replaced the battery three weeks after the brake hose and resistor replacement so that could have contributed to my issues as well.