"When troubleshooting, if an issue seems like it must have an insanely complex solution, it probably doesn't. It's probably something so simple that you just critically analyzed right past it in your little monkey brain."
My van has had many electrical issues thus far.
You know for an early 1990's vehicle, this thing is a hellavan engineering feat. It's packed to the brim with electronics, sensors, wires, relays, fuses, control modules, regulators...Auto engineers are a crazy breed, indeed.
After I bought this van and took it straight to "Little Manny" the mechanic in Los Angeles, I experienced what's called a parasitic battery draw issue.
This means that, even with your vehicle turned off and the key is out of the ignition, something continues to draw current (electricity) from your battery and drains it over time.
This means, if you don't run your vehicle long enough to allow the alternator to recharge your depleted starter battery, that battery will eventually delete to the point where you cannot start your vehicle.
I noticed the draw on my starter battery after I installed my solar panels, charge controller, house batteries, and 2000-watt pure sine wave inverter at Manny's shop.
It was significant, or seemed significant at the time. I put my multimeter in voltage mode, measuring from the + and - posts of the starter battery and I just watched voltage drop... 12.77... 12.76... 12.75... 12.74....
I couldn't figure it out. The van was off. I started disconnecting fuses in my fuse box and still the battery continued draining.
So, I disconnected the battery from the van entirely while I thought.
I called my brilliant, mechanical/electrical-engineer-minded uncle, Joe, and together we called his brilliant friend, Tim, to help me conceptually wrap our heads around the issue and to brainstorm how to solve it.
When I'm troubleshooting a problem. My brain must visualize specifically what is going on or I'm useless. I need to see water flowing from point to point. As my friend James told me during my days working in the Audio department of the Oprah Winfrey Show Audio:
"Always remember...Source & Destination."
I made a huge electrical diagram, as far as I understood, in Photoshop and sent it to Joe and Tim. They told me how to best troubleshoot the parasitic draw.
Sadly, Manny had a malfunctioning battery charger, and we ended up wrecking that starter battery. Never good to see smoke billowing up from boiling pools of lead acid.
I put a new battery in after taping up a bunch of bare wire from the old security alarm system and reseating every fuse in the fuse box and the issue seemed to be resolved.
That was September / November of 2016.
Fast forward to June 2017. The battery draw returned.
It was such an overwhelming thing for me that I ended up adding a blade battery disconnect switch on the positive side of my starter battery and got into the habit of tediously turning the van off, opening the hood, and opening that switch to disconnect the battery every time I walked away from the van.
A workaround, not a fix.
I decided to add a fancy alarm system to the van since everything I own is inside. But I ran into a big problem: the alarm only works if it's powered. The battery has to stay on 24/7.
So, I couldn't just use my cheat battery disconnect switch anymore. I had to find and fix the electrical issue.
The guys at the alarm installation shop seemed knowledgeable enough, so I asked them to help. I showed them my now more complicated wiring diagram, and told them the steps I had tried to find and eliminate the parasitic draw.
The tech tried most of the same steps. Disconnecting fuses. Tracing wiring through an endless labyrinth of unlabeled harnesses.
He came out to me looking defeated and said dude... it's beyond the simple stuff now and if you want me to continue tracing this, I can, but we might be looking at like 6+ hours of billable labor. I might have to start taking a look into the engine sensors and power control modules and such.
I was like, well, it needs to be done either way, so go for it.
While I was in the waiting room, I was still churning in my head about what it could be.
I looked through old my van fix-it lists, and saw this one item.
"Ignition slot + headlights pull switch ring lights not turning off."
I ran out to the tech and said: Hey, what about this problem...could it be something in my steering column that's not turning off? And he was like hmmm, I'll check it out and get back to you.
About an HOUR later. He came out to me smiling and said "You gota see this."
I closed my laptop and nearly tripped over myself following him back into the shop from the waiting room.
He said look there. I said ...at what? He pointed to the headlights switch, which is this cigarette lighter shaped push/pull switch that you pull out towards you to turn the headlights of the van on. That switch also has a rotating function; you can turn it left and right to dim and brighten the instrument panel lights.
What I and the techs didn't realize is that this fancy switch also had two "click" positions that bypass the ignition master relay and allows current to be drawn from your starter battery if left clicked on when the vehicle if off.
The far right click position of the the headlight pull switch dial is an "always OFF" feature for assist lights like the LED rings and overhead cabin lights.
The far left click position is the "always ON" feature for the assisted entry lights, LED rings, and overhead cabin lights which each have their own rocker switches.
I had turned the dial all the way to the left to make my instrument panel lights the brightest, but I had gone far enough to put it into that far left click position which is the "always ON" position which allows current to flow to the LED ring lights and to my overhead cab lights.
The cab lights were all switched off, but if I switched them on in that always ON click position, voila! they illuminated brightly.
Even though those lights were switched off, something in the circuit was drawing enough current to drain my battery over time.
Mystery solved. Annoyingly simple solution.
Note on multimeter usage:
Amp mode must be used in Series. +/- leads indiscriminately bridge the + leads of the car circuitry and the + post of the starter battery. Current flows through the multimeter to close the circuit. 10A fuse mode
Volt mode must be used in Parallel. +/- leads of multimeter go to respective +/- posts of starter battery. 200mA fuse mode