He should move to San José.
I fixed a parasitic drain on my car in 408 days
61–70 of 515 posts
Re: I fixed a parasitic drain on my car in 408 days
#62Well 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…
> 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.…
The problem with specializing in these issues is that most customers will be dissatisfied when you charge them thousands of dollars to reset a minor module on their car.
How many hours of shop time are you willing to pay for with no guarantee of a solution, and very few (if any) parts replaced?
Re: I fixed a parasitic drain on my car in 408 days
#63Well 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…
> 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.…
If you can identify the fuse for the unit, it might be less annoying to pull it when parking rather than hooking up a charger.
Re: I fixed a parasitic drain on my car in 408 days
#64Earlier quoted context omitted.
Probably should get a brand more reliable than Audi...
I hear people say that about my BMW, and realistically the hassle of some reliability issues is nothing compared to driving the lifeless husks of cars they recommend instead. (there are reliable sports cars, but it significantly limits the pool you can select from)
I like Mazda and Honda (in that order). Japanese reliability, sporty handling and a turbo engine for a fraction of the german cars.
Re: I fixed a parasitic drain on my car in 408 days
#65> Dealer: said my car was fine and returned it to me. My car died the next morning.
Least surprising finding
Re: I fixed a parasitic drain on my car in 408 days
#66I had a parasitic drain on my Tacoma from my Automatic device (OBD-II reader / GPS tracker). I parked in a garage with no cell service and it drained the battery by constantly trying to connect. It was a non-issue when I commuted daily but started killing the battery when COVID happened and I switched to WFH.
Hard for mechanics to diagnose because they had no idea what that device was and also one of their first steps was to unplug it, put it in a cupholder, and plug their own OBD-II reader in.
Now the Tacoma is parked again most of the time because I got a Tesla and I'm noticing a voltage drop. I need to do more research, I don't know if this is normal for being parked or if there's a drain.
Re: I fixed a parasitic drain on my car in 408 days
#67Well 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…
>It seems like mechanics really don't like digging into the electrical part of the car. If you've ever seen a car's complete wiring harness you'll know why. It's not only because there's three gazillions of wires - they're also heavily insulated with tape that makes it a nightmare to access those wires in the first place.
>there's three gazillions of wires
My old math teacher would deduct points for not listing the units.
Re: I fixed a parasitic drain on my car in 408 days
#68My 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 finding an issue with my Subaru Legacy, when no other mechanic could (I tried 3). The issue was that the car was old, first gen OBD, he downloaded some legacy asm ECU reader and made a diagnostic cable from spare parts, the issue was that the car would not start when cold, or be extremely hard to start. The culprit was damaged wire that tells the ECU that the engine is in cranking condition, therefore needs a different fuelling mode, without seeing this mode there was not enough fuel to start when cranking. Eventually this was found by hooking up an oscillograph to see the injector impulse length (duty cycle), as the old gen. diagnostic didn't show any errors, he compared a working car injectors to mine when cranking cold and found this. 10 years later I'm still amazed by his skill and dedication, I'd have scrapped the car otherwise. The car was sold eventually to another person who restored it (rust repair mostly) and his wife still drives it to this day, a 1994 Subaru Legacy.
Re: I fixed a parasitic drain on my car in 408 days
#69Earlier quoted context omitted.
It's fairly straightforward if the car is unmodified, as everything should be fused. Multi-meter between positive terminal and positive lead and pulling each fuse to see when the drop goes away will isolate the circuit. Then you've narrowed it down pretty far and can go from there. The horrible thing is if the car is modified, and you discover an un-fused circuit.
I’ve had unknown draws before and many times they’re not constant draws. A constant draw is easy and quick to find. A draw that only happens when some module or other wakes up is a lot harder to find.
I recently watched a YouTube video from someone who'd tracked a nasty intermittent parasitic draw [0]. The problem only happened after turning the ignition on & back off (so the standard test of disconnecting the battery & reconnecting via the ammeter wouldn't show it), and the draw cycled between 3.6A and 0.3A.
Also, after turning the ignition on & back off there were a lot of (normal) transient draws (from things like the dome light that don't turn off immediately). Even with the problem circuit disconnected, it drew around 6A (!) immediately after the ignition was switched off, dropped to 0.4A after about a minute, and sat at that level for another 9 minutes before dropping again to 0.06A. That means if he hadn't waited ~10 minutes per test, he'd have been chasing draws that were actually normal.
Combine an intermittent fault with intermittent normal behavior, and you've got a troubleshooting nightmare.
Re: I fixed a parasitic drain on my car in 408 days
#70Earlier quoted context omitted.
>It seems like mechanics really don't like digging into the electrical part of the car. If you've ever seen a car's complete wiring harness you'll know why. It's not only because there's three gazillions of wires - they're also heavily insulated with tape that makes it a nightmare to access those wires in the first place.
>there's three gazillions of wires My old math teacher would deduct points for not listing the units.
Numbers of wires