Background info: I spent the whole week inside the engine bay swapping engine related parts, and another night with the console & under dashboard removed, swapped the shifter, installed a factory radio (car has never had any radio since I've owned it), and cleaned up some spliced wires that I believe was aftermarket stereo related. I didn't touch ANYTHING near the headlights.

I had the battery & tray out of the car. After re-installing the battery, as soon as I hooked up the negative lead, the passenger headlight motor started humming. It sounded like a pump was running, didn't hear any gears grinding or anything like that. It didn't move at all, just hummed. I've never had any headlight problems before...but I do have HID's installed (haven't yet purchased the aftermarket resistor that restores the normal motor function).

I haven't pulled any codes yet or done anything besides a visual inspection. I pulled the headlight motor fuses and verified that was where the noise was coming from. I did a search and found the headlight wiring diagram...but there doesn't seem to be any wiring related anywhere in the rest of the car.

Is there something I may have overlooked? Is it safe to start troubleshooting this with the key in the ignition to pull the codes?

 

I had removed the intake to replace the MAP sensor, swapped the injectors, changed the spark plugs & wires, replaced the MAF connector & airbridge, re-routed passenger o2 sensor, replaced some vacuum hoses & did a compression check. That's about it.

I also currently have the A/C clutch relay & compressor fuse pulled, because I have not yet got the parts to fix a massive PAG leak from the back of the compressor seals. I also still have the Select-A-Ride switch disconnected.

 

What you most likely heard was the headlight control module, which is located under the passenger headlight assembly. They do not respond well to a low voltage condition, so make sure your battery is fully charged. I'm not clear on why you think there is a "dead short"? Did you find a blown fuse?

 

No...didn't find any blown fuses. I just heard the sound of a pump running and just pulled fuses until I could find the source of the noise. I didn't know the headlight module was capable of making a noise like that.

The battery was drained pretty good from doing a thorough compression check...but since then I took my battery to the parts store and had them do a deep cycle charge on it because I've been having a low voltage condition while the engine is running. They said my battery was just fine, so I figured it might be the alternator.

I forgot to add before...I've been getting the dreaded "Charge Fault". I haven't fired the vette up for a couple weeks now, I had forgotten about it until just now

 

I pulled the codes on the DIC recently, the only 2 that were marked with "C" was for the Outside Air temp sensor open & Steering position sensor malfunction. No help there...

 

Battery negative cable sparks pretty good when I reconnect it. I already pulled all 3 fuses related to the radio...still sparking. No lights or noises or anything.

Guess I'll start by pulling every fuse 1 by 1.

 

Guess what.....they all do. Why, because there are a number of active systems.....one of them being the headlight control module.......and if it's still making noise, the battery is probably low.

I certainly hope that is not the reason you "think" you have a short, and have started pulling fuses.....just because the negative cable sparks when reconnected. ....

 

The sound of a pump running, the first thing I think of is the air compressor for the lumbar supports

 

Battery is sitting at 12.4v. I read in other threads about current draw and the active systems being present when key is off. I was *hoping* that I could narrow it down to only several components and check amperage draw at the fusebox. I am not sure what else I can do.

I will swap the battery out with my daily driver first and see what happens.

 

Sorry, I still don't understand what he problem is here

 

I admit it fooled me pretty good...but the sound goes away as soon as I pull the headlight fuse. Coming from right where that module is located.

 

Well that awfully loud noise coming from the headlight module. If my battery turns out to be good...wouldn't there have to be a pretty significant short to drop the voltage enough to cause that noise?

Should I just go ahead and take the headlight off and start by looking at the module?

The noise won't go away until I pull the fuse out.

 

Leave the battery alone, and put all fuses back in. Hook it up, start your car. Let it run for a few minutes, and cycle the headlights up and down. Shut down the engine, and have a listen for the noise.

 

Okay...will do.

I just dropped my injector size to 28lb. down from 48lb. Havent fired it up yet or sent the PCM off yet to get adjusted for the injectors. Probably not a good idea, I guess

Give me a week or so and I'll update on this

 

Exactly what was touched on the engine?

 

I just went through an engine swap in the past 50 miles. Went to a smaller engine (6.0L) with just small H/C & bolt-ons. The 48lb injectors were a remnant of the pulled 408ci that was once supercharged by a previous owner.

I did not have a charge fault or electrical issues until after the engine swap.

Since I have had the battery disconnected, I touched the passenger O2, MAF connector, Intake manifold, injectors & fuel rail, spark plugs & wires, coilpack harness, alternator (disconnected to pull intake), MAP sensor, coolant sensor, knock sensor, 160*stat, hood lamp disconnected. I also have a Vararam B2 that sits somewhat loosely. I was moving that around a bit trying to get my airbridge off.

One thing that I found is the O2 harness was melted somewhat by the header on the passenger side. It doesnt throw any codes however.

 

With all the work, you might have damaged a wiring harness somehow. Check them over as much as possible. I also agree to try cycling the headlights up and down. If the battery is well charged then you can do it without the engine running.

FYI, a "dead short" would either blow fuses or start fires.

Peter