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I fixed a parasitic drain on my car in 408 days

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Re: I fixed a parasitic drain on my car in 408 days

#181

Post by pvaldes »

jessaustin wrote: post #144
bityard wrote: post #131

Earlier quoted context omitted.

I can recommend searching for "South Main Auto parasitic draw" on YouTube. The guy is a genius at electrical troubleshooting. His strategy isn't to pull fuses, it's to set the car sit for at least 30 minutes or so (with key off) and then check each fuse with a multimeter to see which has current on it, and then check everything on that circuit. Arm yourself with schematics and wiring diagrams, otherwise it'll end up…

It would take someone more skilled than I, or with better tools, to check current in a fuse box without removing fuses. Maybe I should watch that guy and get better...

A multimeter is cheap and really easy to use. This is the safest way also

Re: I fixed a parasitic drain on my car in 408 days

#182

Post by driverdan »

jws wrote: post #2

I have failed to find the parasitic draw on an RV (slower than this one, it takes a couple weeks to kill the battery). I finally got a "Top Post Battery Master Disconnect Switch", which is a little dinglebob that goes between the battery post and cable and lets you easily break the circuit. I highly recommend the $12 solution for an intermittently used vehicle.

I'm surprised it didn't already have a master shut off switch next to the battery. You should always shut off / disconnect the battery when not in use because, as someone else pointed out, the propane detector will drain it.

Re: I fixed a parasitic drain on my car in 408 days

#183

Post by pvaldes »

JohnFen wrote: post #167
lylejantzi3rd wrote: post #28

Earlier quoted context omitted.

> It seems like mechanics really don't like digging into the electrical part of the car... Tell me about it. I'm in a similar boat. My audi a4 has had a parasitic draw for the past 10 years. My mechanic didn't want to take the time to address it because that sort of thing takes a serious amount of time and he's always backed up. I got out my fluke and narrowed the cause to what I believe is the comfort control unit.…

I wonder if installing a switch to disconnect the car's battery entirely would be an acceptable (but obviously hacky) solution.

That would depend on the car brand. Not so good idea in some brands.

Assure to write somewhere your radio code password first.

Re: I fixed a parasitic drain on my car in 408 days

#184

Post by somat »

JohnFen wrote: post #167
lylejantzi3rd wrote: post #28

Earlier quoted context omitted.

> It seems like mechanics really don't like digging into the electrical part of the car... Tell me about it. I'm in a similar boat. My audi a4 has had a parasitic draw for the past 10 years. My mechanic didn't want to take the time to address it because that sort of thing takes a serious amount of time and he's always backed up. I got out my fluke and narrowed the cause to what I believe is the comfort control unit.…

I wonder if installing a switch to disconnect the car's battery entirely would be an acceptable (but obviously hacky) solution.

Not really, When powered down(battery diconnected) the computer then has to re learn parameters/pass internal validity checks. On a well preforming system this will be done in as little 1 or 2 rides but on a marginal system this can take many rides. the computer may not enter closed loop mode until these checks pass.

closed loop mode is where the computer set it's output values(fuel air ratio, timing etc) based on it's input sensors. open loop mode is where it sets it's outputs on known safe working values, but it may not run particularly well. i think this is related to the so called "limp mode"

Note My knowledge on this subject is very out of date. I had to figure it out for my old 2001 car. Newer vehicles may actually have flash storage and the computer parameters survive power out.

Re: I fixed a parasitic drain on my car in 408 days

#185

Post by gridspy »

jessaustin wrote: post #144
bityard wrote: post #131

Earlier quoted context omitted.

I can recommend searching for "South Main Auto parasitic draw" on YouTube. The guy is a genius at electrical troubleshooting. His strategy isn't to pull fuses, it's to set the car sit for at least 30 minutes or so (with key off) and then check each fuse with a multimeter to see which has current on it, and then check everything on that circuit. Arm yourself with schematics and wiring diagrams, otherwise it'll end up…

It would take someone more skilled than I, or with better tools, to check current in a fuse box without removing fuses. Maybe I should watch that guy and get better...

You measure the voltage across the fuse. Then you look up the fuse's resistance in a datasheet. Current is Voltage / Resistance.

Re: I fixed a parasitic drain on my car in 408 days

#187

Post by lylejantzi3rd »

JohnFen wrote: post #167
lylejantzi3rd wrote: post #28

Earlier quoted context omitted.

> It seems like mechanics really don't like digging into the electrical part of the car... Tell me about it. I'm in a similar boat. My audi a4 has had a parasitic draw for the past 10 years. My mechanic didn't want to take the time to address it because that sort of thing takes a serious amount of time and he's always backed up. I got out my fluke and narrowed the cause to what I believe is the comfort control unit.…

I wonder if installing a switch to disconnect the car's battery entirely would be an acceptable (but obviously hacky) solution.

This isn't a good idea for an Audi. The computer doesn't like going without electricity. It runs a bit rough for a day or two afterwards and sometimes will "forget" how much gas is in the tank.

Re: I fixed a parasitic drain on my car in 408 days

#188

Post by ryandrake »

karolist wrote: post #68

My father (a professional auto mechanic) took about 6 months to find a random engine shutoff during harder cornering in his Toyota, the culprit was a damaged inner insulation layer for a few wires within the wrapped wiring harness for the ECU, engine moving on the engine mounts would sometimes cause a slight harness shift and a short would cause a hard reset of the ECU. Another story I have is my computer geek friend…

Your friend’s fuel issue seems a lot like the intermittent no-start, low fuel pressure issue I have been debugging (3-series) for over a year now. It has defeated three dealerships and two independent mechanics so far, so I’m taking over the diagnosis now. No clue yet but today’s cars have too damn many computers in them.

Re: I fixed a parasitic drain on my car in 408 days

#189

Post by sterwill »

jerrysievert wrote: post #142
overthrow wrote: post #3

Well this is timely. I have a parasitic draw on my NC Miata. The first mechanic just replaced the battery. The second told me it's normal for the battery to die if you don't drive it for 3 days (because "cars have computers now"). It seems like mechanics really don't like digging into the electrical part of the car... but these days that encompasses more and more of what can go wrong. Without time to dig into it myse…

3 days is definitely not good for an NC. That said, mine is usually around 2 months before the battery is drained. That should give you some better expectations.

2006 NC owner here with a reasonably new battery. I keep it parked in an attached garage, so no extreme cold or heat. Mine will always start after leaving it for 1 month. I probably left it for 2 months at some point in the last two years, and it started, but that feels like pushing it.

The next time a mechanic tells you cars can't sit for a few days without a battery drain problem, ask how people who park at the airport get home after a two-week trip.

Re: I fixed a parasitic drain on my car in 408 days

#190

Post by pvaldes »

ChuckNorris89 wrote: post #132
stocknoob wrote: post #12

Earlier quoted context omitted.

Or disconnect the battery (you’ll have to reset the clock, etc., which is annoying).

Not great advice. Most new-ish cars also store the dinamic engine calibration data in ECU RAM so if you disconnect the battery you can find your engine running harsher next time. So are the values of the headlights auto leveling system and other stuff. You're also risking to reset the radio/media unit security code (on cars that aren't too new but also not super old), which if you got the car second hand and the form…

There are systems that can be attached to save the parameters from the car before you disconnect the battery or even to provide electricity to the car while the battery is being checked in another room. Not common to find and most people don't need them, but they exist.
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