Electrical Gremlins (SOLVED??)

[RootMeanSqr]

Here are some of my many symptoms, all of which appear to be random and occasional, nothing repeatable yet.

• Remote lock/unlock not working.
• When turning the key to start, I get nothing, no lights, no cranking, nothing. A few more tries, and it kicks in.
• While driving, if the headlights turn on, I get all dash lights (ABS, ATRAC, Battery?, etc.) - maybe I should take a picture, but I've been driving... Oh, and at the same time as the lights on the dash, my Stereo Head Unit will turn off and then finally reset. Not sure if it's the Battery power or the IGN signal that's doing that.
• Turning on the headlights causes a quick dip in the dash battery gauge, but it returns. But my Radio HU resets. Very Odd. Turning on my 20" LED light bar has no effect.
• After it starts, my winch beeps at me complaining that it needs to pair with the remote, which tells me that it lost power some how.

Okay, so the winch is interesting because the Neg is wired direct to battery, the Pos is wire to battery through a 300A fuse. So I wouldn't think that any of the no-start and no dash lights would affect the fuse, doesn't make sense to me. Seems to me like there must be an occasional short happening or a loose ground or something else that causes the voltage to drop.

I've measured the battery with a Fluke DMM, it's 12.4 at rest and when cranking is 11+, so it seems to be able to supply enough cranking current. I can take it in for testing, but since the voltage doesn't drop below 11 during cranking (as far as I recall) it doesn't seem like the issue. And in the no-start / no-dash lights condition, I would think that even if the battery were low that I would get some sort of lights. I've wondered about the ignition switch, but don't see how a faulty switch would cause the voltage to the winch to drop so much that it resets.

Open to any suggestions. In the meantime, I'll probably start unplugging things like the winch itself, LED fogs that replaced the factory fogs, etc.

 

[saucebox]

Battery + all engine bay ground connectors are things to check for sure, and have a look at the fusible links also. There was a recent thread with some weird no-start issues that turned out to be the fusible links.

If I had to bet, I'd bet on the battery. Should be easy enough to have it tested.

 

[RootMeanSqr]

Battery + all engine bay ground connectors are things to check for sure, and have a look at the fusible links also. There was a recent thread with some weird no-start issues that turned out to be the fusible links.

If I had to bet, I'd bet on the battery. Should be easy enough to have it tested.

Good point on the fusible links, I will check that as well. Thanks!

 

[RootMeanSqr]

I was able to reliably get the dash lights to all come on and the Stereo Head Unit to cycle power. With the vehicle running, all I have to do is turn on the headlights and I see the battery voltage dash guage significantly dip and then come back up. I've tried this with the fogs on and off, no difference, simply turning on the headlights will do it. Really seems like there is a high impedence point somewhere like a bad ground that causes everything to sag momentarily. I'll do more checks and report back. Trouble is that I went all day Sunday & Monday with no issues. Go figure.

 

[IndroCruise]

I was able to reliably get the dash lights to all come on and the Stereo Head Unit to cycle power. With the vehicle running, all I have to do is turn on the headlights and I see the battery voltage dash guage significantly dip and then come back up. I've tried this with the fogs on and off, no difference, simply turning on the headlights will do it. Really seems like there is a high impedence point somewhere like a bad ground that causes everything to sag momentarily. I'll do more checks and report back. Trouble is that I went all day Sunday & Monday with no issues. Go figure.

Any chance of unwanted moisture leaking into strange places, especially the fuse/relay panels behind the covers in the footwells forward of the front doors? I have had this due to a windscreen leak, some have had similar due to leaks from sunroof drains, some have had it when windows were left open in heavy rain or while putting the vehicle through a carwash, others have flooded the vehicle in water crossings. Moisture from these sources causes shorts and current leakage resulting in all sorts of strange lights in the instrument panel and other strange effects, usually fixed by removing the covers, drying out the fuse/relay panels, and fixing the cause. Just a thought -- maybe nothing to do with your situation.

 

[RootMeanSqr]

TL;DR: I'm hoping I've solved my issue. My home made copper bus bar connecting the fusible link block to the MIL-style terminal seems to have oxidized creating high impedence.

While probing around, and able to reliably cause the voltage to momentarily sag when turning on the headlights, I was noticing that the voltage at the metal bracket feeding the fusible link block was sagging, but the battery terminal itself was not. So I measured voltage between the fusible links and the battery terminal and was reading 0.8V!! This told me that I have a high impedence path between the fusible links and the battery itself. The bolts are all tight, but I slightly budged the connections and the connection was better. I'm guessing that the copper had oxidized creating insulation between connections. When I would drive, there was probably enough movement to make good contact for a while, and then fail again.

I sanded copper and reassembled; all seems good, for now. I think it's time to replace that junction though with something other than copper. But this has lasted for several years, so I should have some time.