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> 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 parasi
by lylejantzi3rd 4y ago
> 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 can't replace it myself because it's a coded part. My mechanic won't do it because he won't confirm that's the cause.
None of the other mechanics in my area have the equipment. Even the Audi dealership won't touch it because they're backed up too. So, I keep a battery jumper in the glove box and hook the battery up to a tender when I can (outdoor parking).
I don't know what I'm going to do for my next car. Pretty much every car made after 2010 has coded parts and are more computer than mechanical. It does make me tempted to learn the electronics part and open a garage that focuses specifically on fixing electronic issues in modern cars.
- cwillu 4y agoIf you can identify the fuse for the unit, it might be less annoying to pull it when parking rather than hooking up a charger.
- lylejantzi3rd 4y agoThat's a great idea. I can't believe I didn't think of that. Thanks!
- jessaustin 4y agoPulling fuses is a pretty reliable way to find the relevant fuse in the first place. If the battery doesn't run down while a particular group of fuses is pulled, the one you want to pull is in that group. Start with half the fuses, then narrow down. You might have to reprogram your radio channels...
- bityard 4y agoI 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 being something of a wild goose chase. (The idea being if you start pulling fuses, you can "reset" various computers in the car, which may show up as a false positive. It can take up to 30 minutes or so for all the various computers in a car to all go to sleep, although it's usually only a few minutes for most cars.)
- jessaustin 4y agoIt 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...
- pvaldes 4y agoA multimeter is cheap and really easy to use. This is the safest way also
- gridspy 4y agoYou measure the voltage across the fuse. Then you look up the fuse's resistance in a datasheet. Current is Voltage / Resistance.
- MaKey 4y agoAFAIK the fuses have contact points you can use to measure the current.
- cwillu 4y agoYou can check continuity across the contact points, but measuring a 75mA current via the voltage drop across a 0.0034ohm resistance (give or take) means reading 0.2mV, which is… borderline for a consumer multimeter.
- dn3500 4y agoIf it were me, I would pull the fuse, then jumper the block over to a different fuse on a circuit that is off when the ignition is off. Then you never have to think about it again.
- asciimov 4y agoThey also make switches for fuses, so that you can kill the circuit without pulling the fuse.
- elteto 4y agoIf you are going with a hack then _this_ is the way to go.
- ssharp 4y agoI wired in an aftermarket DVD player in an old car and tapped into a fuse that was supposed to not draw power when off. Of course, it did draw power so the DVD player never shut off. It wasn't too much of a draw but I didn't want to end up with a dead battery situation because of it so my solution was to just plug the fuse tap in when the kids were in the car and wanted to watch something. I'm sure there was a more elegant solution (find a different fuse, rig up a button, etc.) but this was the path of least resistance and wasn't really annoying to do.
- aidos 4y ago“path of least resistance” is very fitting.
- brokenmachine 4y agoAftermarket head units should have two power inputs - one for standby, and one that only gets power when "accessory power" is on. Every car I've owned I've been able to wire it up so that works, then it only turns fully on when the car is on. I avoid very new cars like the plague though, so not sure how different they are. It makes me anxious thinking about all the bullshit in new cars - touch screens, coded parts, 4G connections with GPS tracking, etc etc.
- ssharp 4y agoThis was an rear-seat overhead DVD player, not a console one. Although, I probably would have been better off wiring to the head unit instead. At the time, I still had the factory one in there so it's not quite as expandable and more complicated to add stuff to.
- acapybara 4y agoWiFi arduino + disconnect relay on the battery. Completely disconnect battery when not in use.
- BenjiWiebe 4y agoMake sure your relay is rated for enough current.
- antod 4y agoYeah, I had an old car where the useless tape deck developed a short (I think) that would drain the battery after about a day. I didn't know it was the stereo until I played around with removing fuses one by one though.
- addisonl 4y agoProbably should get a brand more reliable than Audi...
- BoorishBears 4y agoI 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)
- cramjabsyn 4y agoI like Mazda and Honda (in that order). Japanese reliability, sporty handling and a turbo engine for a fraction of the german cars.
- Scoundreller 4y agoI feel like I’ve lucked out in life with an ‘08 6MT N52 e90 and an ‘05 Corolla with a 1ZZFE.
- legitster 4y agoThat's fair, but it's funny because that's how I always felt about BMWs. My buddy loves them but I always felt like they were so... sterile. Unless you are at a track or love cutting off people in traffic it feels really hard to have any fun in one.
- JPws_Prntr_Fngr 4y agoSterile compared to what? Is there another manufacturer of acceptably-tuned rear-drive sedan chassis out there at a semi-reasonable price point that I should know about? (I'm talking about pre-2010 BMW here; I would totally agree with most new ones being sterile)
- johncalvinyoung 4y agoAs a current owner of a 90s Jaguar and an 05 Volvo, I've been looking at low-mileage E90 era BMWs for my next daily driver. Not too scared of moderately expensive maintenance, but would like it to be more reliable than the Volvo has been.
- nickff 4y agoThe 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?
- peteradio 4y agoDude's been tending his issue for a decade, I bet he'd have at least those like him as a customer. In a metro he might have a pretty lucrative business. On the other hand in the metro there is probably someone who already does this work, but they are very hard to find!
- jopsen 4y agoHow do potential customers find your specialized shop? Most people will give up, stop researching and buy a new car when the dealer tells them it can't be fixed.
- yurishimo 4y agoWord of mouth w/ cars is hugely important. Anybody with a good mechanic will tell you about them. Shoutout to "The Hondew Shop" in Dallas. He does great work on all Honda/Acura products!
- newjersey 4y agoFord lied to its own dealership when my coworker went to them about a transmission slip with his 2012 Ford Fiesta. He had the people at the dealership drive the car. They acknowledged the problem and got on a call together with Ford. Ford refused to even entertain the idea there was a flaw but less than a year later they came up with a "software patch". Pete would bring it up with anyone he met. Do not buy a Ford Focus / Ford Fiesta with automatic transmission.
- jopsen 4y ago> 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? Imagine opening a computer software support business where you bring in your old proprietary binary programs that you got from who knows where, and the business is to fix bugs you've found. Maybe some really big enterprises would pay for that sort of thing. But I doubt it would be feasible for consumer stuff. It would be a crazy/fun kind of business to run. I'm sure it probably exists.
- Eumenes 4y agoI'm looking into buying a reliable older vehicle, pre 2000, and just rebuilding the engine
- ilyt 4y agoIf car is at the point of engine rebuild you'd probably have to replace half of the suspension too
- bronson 4y agoAt least! When my engine finally needed a rebuild, so did the transmission, steering box, CV joints, and center differential. And you're right, it needed new bushings, shocks, springs, and balljoints.
- dsfyu404ed 4y ago"need" starts being a very subjective word when talking about some of these components at high milage.
- ilyt 4y ago"While I'm at it might as well" And honestly on something that used it might be the best, taking it apart again just to replace the thing you thought you might not need to is PITA
- ilyt 4y agoYeah, I recently bought a car (I had driving license for 15 years before that but for 14 of them I didn't drive coz I moved to the big city), and basically bought one of cheapest, had to replace dampers last year, this year one of springs broke, one of calipers have some problems and apparently one of previous owners installed lambda probe emulator to hide dead catalytic converter... Tho a bunch of that might be because I bought "sporty car" and those rarely have easy life in the first place...
- lylejantzi3rd 4y ago
- sokoloff 4y ago> My mechanic won't do it because he won't confirm that's the cause. My experience is that a lot of independent mechanics will do what you ask them to do, so long as they think it’s not unsafe and have confidence that you’ll pay the bill without complaint when the task is done whether or not the problem is fixed. Probably not a good “this is my first time meeting you, but please replace my flux capacitor” but if you’ve got a history with the shop, I’m surprised you couldn’t talk him into it. (I worked in a shop briefly in college. We’d do what the customer wanted, including installing parts they bought, but the only warranty was on a “we spent an hour; you paid for an hour; thus ends the transaction” basis.)
- HeyLaughingBoy 4y agoYes. I had a problem with a leaking transmission once and the shop refused to accept my diagnosis because "in all my years servicing transmissions, I never heard of that failing." Finally, the service manager agreed to check it out with the understanding that if I was wrong, I still had to pay for the time they spent investigating. I was right :-)
- leetrout 4y agoThis was me with a Suzuki vstrom with a bad solenoid. Mechanic ran 12 volts through it on the bench and refused to accept it wasnt working in the bike. Bought my own solenoid online and surprise the bike started working again.
- dcormier 4y agoThey were unit testing when they needed to be integration testing.
- wpietri 4y agoDebugging spider sense is definitely an upside of spending years working with terrible code. I once moved into a place that was great, except the shower would start out hot, quickly drop to warm, and then stay warm for as long as we cared to try it. I hated this, so every time I showered I'd spend some time trying to debug it, despite knowing nothing about plumbing. Eventually I asked myself: why do normal hot water heaters work the other way, where they stay hot a long time and then get pretty cold? Clearly, there's some way of keeping the incoming cold water separate from the already-heated hot water, like by putting the output pipe at the top and the input pipe at the bottom. But if you reverse them, you might get what we had. I leapt out of the shower and felt the hot water heater pipes and sure enough, reversed. My landlord came over shortly thereafter and fixed it, and I felt very smug when I had my first properly hot shower.
- sixothree 4y ago> Even the Audi dealership won't touch it because they're backed up too. Getting an appointment at my Audi dealer is always 6+ week minimum wait. I don't think I've ever dealt with a dealer this consistently backed up. And my issues have been recalls and brake problems; but simple oil change is a similar wait time.
- JohnFen 4y agoI wonder if installing a switch to disconnect the car's battery entirely would be an acceptable (but obviously hacky) solution.
- pvaldes 4y agoThat would depend on the car brand. Not so good idea in some brands. Assure to write somewhere your radio code password first.
- somat 4y agoNot 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.
- aksss 4y agoYes, my Audi did not like being disconnected from power. If I remember correctly, it didn't go into limp mode but it was in some partial alarm state when it reconnected such that one had to mimic the Contra cheat code with their fob to get it to shut up. I jest, but yeah. Battery dead was not a condition with a transparent recovery.
- tempestn 4y agoNot to mention more minor annoyances like losing radio stations and other settings.
- gsich 4y agoIt's insane that this keeps happening. Computers can remember BIOS settings for probably 40+ years now.
- Nifty3929 4y agoWhat are coded parts? I spent a minute googling and couldn’t come up with anything that seemed right.
- jobead 4y agoI believe this means that the part's computer has the vehicle's VIN loaded into it with a computer that can only be purchased/used by a certified technician. If he was to buy a new part, it would have a blank VIN; and if he pulled one from a junker, it would have that car's VIN. (edit: should also say, I think a VIN mismatch would cause the ECU to refuse to work with that part and shut down)
- Nifty3929 4y agoWell that's dumb. I've never heard of that before. But I guess I shouldn't be surprised. Thanks!
- owenmarshall 4y agoIt gets even more fiendish than that - you can have entire linked dependencies of locked modules. My old Saab’s key was locked to the security computer, to the column immobilizer, then to the engine computer. Lost one key? Bummer. Lost all your keys? $2500, several hours of reprogramming time at the dealer, and a bunch of new parts shipped over from Trollhattan. Thankfully the hacking scene has managed to bypass lots of this as Saab no longer exists to make parts. But this was the state of the art in 2003. I’m sure it’s even worse now.
- smackeyacky 4y agoIt's going to get worse - on most cars the CAN bus is not encrypted and the messages are not signed. There was a comment here recently where a tech in the auto industry claimed that one manufacturer was planning to start signing the CAN bus packets. That will mean it likely becomes impossible to do things like re-code the PCM for a motor with a different VIN so you can re-use the PCM in another vehicle. That will be quite hard to overcome.
- gonehome 4y agoIf you’re going to have to deal with it might as well get a tesla which is at least all in on the electronics and the company understands software. The dealership model has really been awful for legacy manufacturers.
- jimnotgym 4y agoGood luck in 5 more years when Tesla decide that your car is now unsupported. I wonder if the Tesla mechanics are measurably better than the franchise dealers? I doubt it. I bet they have fancy testers, but when the tester is not showing 100% the right answer I doubt they are any use at all.
- gonehome 4y agoI've had mine (Model 3) for about 5 years now, so far they updated the hardware for free and it's gotten way better software for free over the air. It's a much better car now then when I bought it (so at least so far, the opposite of what you suspect is true). Service has also been way better for me than when I had cars serviced by franchised dealers, but that may be because I'm in SF. I had an issue and two days later a mobile Tesla service car came to my house and fixed it in my driveway for free.
- jimnotgym 4y agoI said. Good luck in 5 more years when Tesla decide that your car is now unsupported. >Service has also been way better for me than when I had cars serviced by franchised dealers Which franchised electric car dealer are you comparing it to?
- lastLinkedList 4y agoAre they doing that with old model teslas?
- garyfirestorm 4y ago> I can’t replace it myself because it’s a coded part. Can you please explain this? Why does it need ‘coding’? It’s not a VIN specific part I’d think - i.e. engine controller. Also have you explored Ross Tech VCDS tool? You might be able to identify the coding on your part and use it on a new part. Replacing an ecu should be straightforward imo.
- brokenmachine 4y ago>Replacing an ecu should be straightforward Really? I would have thought that'd be one of the most complicated things to replace.
- garyfirestorm 4y agoI’d say an engine controller which needs a specific vehicle information to work is going to be difficult. But an ecu that controls say your headlights, depending on the oem it is just a part with unique part# that can be swapped. I work for one of the American OEMs and have replaced a ton of controllers on vehicles (engineering vehicles and customer vehicle). never had an issue. That being said I know German vehicles are next level pita since I do own an Audi. I just wasn’t aware about the coding part for the Audis.
- KennyBlanken 4y agoIn VAG cars, the ECU and dashboard are often paired to each other for anti-theft purposes, since the immobilizer is part of the ECU itself. To stop people from simply pulling the ECU and replacing it with one keyed to the immobilizer key chip they have - the ECU is paired to the dashboard, which often requires a lot more time and effort to remove. For other modules they're often used across many different cars/engine/transmission/body type and regulatory markets. "Coding" a module tells it what accessories/options it's connected to, what else is in the car, what regulatory market it is in, and so on. There's also "coding" for how the module behaves with certain features. For example, body control modules on US cars won't allow you to use the remote to roll up the windows, but by flipping one of the coding bits, you can enable it. There's also silly stuff like enabling / disabling gauge sweep on the dash. (Explaining this mostly for others, you seem aware of at least some of this)
- TheSpiceIsLife 4y agoHave you consulted an auto electrician? In Australia Automotive Electronician is a trade itself. A good mechanic should be able to point you to their preferred auto electrical workshop when they suspect an issue is outside their own scope.
- 99_00 4y agoEveryone should keep a jumper in their glove box. It's with the price just to see the looks on the faces of stranded motorists you help jump start in one or two minutes after they've been trying for an hour to jumpstart a minivan with a hatchback.
- madaxe_again 4y agoI had similar with my ‘15 Amarok. Battery would reliably be flat after parking for 24h, and I was either told there was no issue or it was unfixable, or I would need a new ECU, a new engine, a new truck. After a short and inconclusive session looking for leaks through the fuse box, and then many, many hours of crawling around under the truck with a voltmeter, I discovered a frayed and heavily corroded +12v lead associated with the tow harness rubbing against the chassis. Fixed it. Issue resolved. Unfortunately, a majority of mechanics simply aren’t competent, and the remainder don’t want to touch jobs which are mysteries, as they’ll just end up with a customer refusing to pay.