Hello, everyone! I recently abandoned thoughts of buying an old Ford Explorer and acquired a 2002 Chevrolet Suburban Z71. I was swayed by the sweet, sweet song of the 5.3, and the Z71 trim. However, the one I grabbed has the sort of things that would usually send me running away from a used car: custom wiring. Perhaps against my better judgment, I purchased the car nonetheless... and subsequently endured its battery dying four days later.

I recovered the battery with charger/maintainer, but have it sitting outside of the car right now, as I put it back in and it once again died within a week. Now I want to better understand what I thought I understood, but apparently don't.

I'm going to have someone with far, far better experience with electrical look at the whole car for me (its rear speakers and subwoofer don't work, either), but until then, can you tell me what the engine bay modifications are for? I was told it's a bypass for the fan, which it looks like, but why? Googling didn't help me much, so I don't know how common this is. How difficult would it be for me to revert this?

I do understand what the other modifications are (custom wiring for an inverter, and -- not shown -- wiring for an OnStar antenna), but took snaps of them too so someone can tell me how horrifying they are/aren't. Though I am a tinkerer, and I'm not scared of electrical per se, I have really never worked with it, so please tell me how bad of a mistake this all may be.

Thanks in advance!

 

The can looking thing is an isolation solenoid. The previous owner probably had a dual battery setup. The second battery was probably running that inverter. The orange wire is probably an ignition signal to energize the solenoid. Without seeing where everything goes, I can't advise you what to do with it.

My advice is to get a Hanes manual, look at the wiring diagram, and go through your starting/charging system one wire at a time to return it back to factory config.

 

Thank you very much for this response.

I was already intrigued by the dual battery setup option, but as an electronics amateur, I have only given it a cursory look ("oooh neat," pretty much). I do have two batteries (one Optima, one off-brand; went with WalMart. My charger/maintainer is a low- but not the lowest-end Schumacher). I didn't see another tray in the bay, but I imagine I could find signs of it if I went looking.

As to what the solenoid is connected to right now, its positive cable is connected to the same contact point on the engine as the battery's. You may have already observed that, as it's dark in the picture, but it's headed to the red box that they're both normally enclosed in.

EDIT: By the way, if anyone's response to my clarification there is "no duh," that's fair—I'm a total electrical noobie, haha. So I will get more pictures of it so things that aren't seen can be seen.

Thank you. I do agree that a Hanes manual is a good idea, so I will get one.

If anyone would like me to take any more pictures, I will gladly do so. I think I will get more of the area around the solenoid and everywhere it's connected to.

A few more of its peculiarities, if anyone has any more feedback:

* I do have the inverter turned off at all times; I have never used it.
* The voltage gauge in the cabin doesn't work, I believe, as it's always dead center and wobbles, which seems disconnected/broken to me.
* Occasionally, while I was driving for a prolonged period at high speeds, all the lights would flicker for a moment, and it seemed to have a predictable timing/pattern. It was very subtle, but with a predictable cadence, maybe every couple minutes or so, almost on the dot.
* The head unit (Pioneer AVH-X2700BS) stays on if the car is turned off, but turns off/on when the car is started.

 

Time for the new photos, alongside as much context as I can provide! I've also bought a Haynes manual and it's on its way.

First, the solenoid, and a faded yellow cable leading away from it into the abyss (I tried to figure out where it was going, but it looks like I can't without getting under it first):












Next, another pic of the chopped-off fan control wiring, and one of the fuse box that shows the cable going into the cabin (I presume through the firewall, given later cabin pictures):














Finally, some pics of the cabin wiring (including a negative run through the hood release, and the cables coming down from the center console to the inverter), and the OnStar antenna:











The car is currently sitting without a battery in it since I don't know what's wrong. Both batteries are sitting in my garage.

Does anything immediately jump out as something I should disconnect/rewire immediately? Or is anything more apparent now with the extra photos, like the fan rewiring?

Thanks again for your help.

 

Diagnosing a drain on a factory vehicle requires a multimeter and your particular schematics. On top of that, you have custom mods. Someone will have to examine your wires, probe the circuits, and troubleshoot the fault. It has to be done hands on, and it takes time. We can't fix your problem over the internet with a few pictures.

Once you get the diagrams, I suggest you sketch out what is connected to what, and go from there.

Burnt out fan resistors (for controlling the speed) are a very common occurrence on GM vehicles.

 

Thanks for the response. I don't mind that you can't diagnose everything for me, and I totally understand. I was mostly hoping to be told if anything seemed alarmingly out of place or otherwise terrifying, or if any of these mods are commonplace. Since you mentioned the fan thing, that does tell me there's a reason for that, so that's good.

Thanks again, I genuinely feel better, as obviously nothing was downright terrifying. I'm gonna let the car continue to sit until I'm actually getting it seen. Don't want to risk frying anything if there is a lurking problem somewhere.

 

Oh don't get me wrong. It's all terrifying. The unfastened wires and loose strands everywhere. Especially the one jammed into the fusebox. I would tear it all out.

The owner's solution to the blower resistors was simply to chop them off, so no that's not good.

 

+1 if you have a draw...unhook all the aftermarket spaghetti first. It/They may be stopping the modules from entering sleep mode or they may be the draw.

 

Thanks for the responses, I sincerely appreciate them. Better for me to know it's as terrible as I feared it would be than being delusional about it being fine.

I forgot to mention that the remains of some old wiring came loose when I moved the bar away from the battery for the first time... so I guess a previous owner was also grounding something there. Super safe, right? /s

Since I am very sure the fusebox one goes to the converter, which I don't need anyway, I'll disconnect that. I'll try to figure out what that sloppily connected mystery cable is connected to and get rid of that also (doubt it's anything essential but I don't know since I can't see where it's going). Guess the fan is staying as-is for now since I need that but I'll replace that too ASAP.

At least the engine has been well-cared for (no leaks), the transmission was recently replaced, and the interior is in excellent condition for the age. Just got to solve these electrical gremlins...

Thanks again.