Electrical System Failure

[MrDrBosox]

Hey all, went out to start my truck this morning ('98) and was in for a fun surprise. The electrical system seems to have cannibalized itself over night. When turning the key to ACC, there is no power to the windows, locks, stereo, or exterior lights. Interior lights are fine. Turning the key further to ON, there is still no power to any of the accessories, and there is a super loud noise coming from the area of the fuse box. Sounds like an air compressor running. Attempting to start there is nothing from the starter, no crank no click. For some reason pushing the brake pedal causes the noise to stop and cuts power to the entire vehicle, including the scan tool I had plugged in.

I've read a lot of threads about the immobilizer problem, but this isn't it. I've also read a lot about fuse boxes failing, but supposedly this one was replaced pretty recently. Open to any suggestions, this is a new one for me.

 

[Njck22]

Battery voltage? Sounds like a cell died and you have no power

 

[Trunk Monkey]

Tried jumping it?

 

[MrDrBosox]

Voltage came back fine, tried jumping as well. Next move is to pull the fuse box and look for any physical damage. Pretty sure the loud noise is something in that area failing, it's starting to smell like burning.

 

[Njck22]

Interested in the history of the fusebox and why it was replaced already.

 

[xplore]

Before ripping the fuse box out, I'd look closely at the fusible links hanging off the side of the battery to make sure they're all well intact and that everything has a tight connection. Make sure the positive and negative leads all make a strong connection.

I don't know if a single bad relay in the breaker box could cause all of the issues, but I would take them out one by one to inspect them. with the noise and odor that you referenced, you should be able to identify if one of the relays was bad by putting it to your nose.

If you do pull the fuse box, there are two wires that connect to the bottom besides all of the plugs that connect to the box. If either one of those nuts were loose, that could cause some major issues, and you did say the fuse box was replaced recently.

 

[ramangain]

Track down that air compressor noise. Chances are high it will help you further diagnose the actual issue.

 

[MrDrBosox]

In the interest of closing this thread for anyone who comes across it later, check your ground connections! I chased this problem intermittently for probably 18 months and even parked the truck for a while because I was so frustrated by it, and it repeatedly left me stranded. Someone suggested that I pull all the ground connections and hit the mounting points with a wire wheel, and I've never had another problem since. Felt like an idiot but at least it runs now!

 

[excessive]

thanks for the follow up