> 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.
> 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.)
Yes. 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.
Debugging 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.
I once spent over a year debugging a furnace. It would run fine, except every now and then on it would just refuse to turn on for a day or two. Eventually noticed it was only rainy days, and was due to it thinking the exhaust was blocked because there wasn't enough pressure differential between input air and exhaust.
Turned out the installer had failed to put in the high altitude kit which told it to expect a smaller pressure differential. Mostly it was fine, but on rainy days with low barometric pressure, the difference would drop below threshold. But I had to be home for enough rainy days to figure it out.
This 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.
I've done that twice with some shops I didn't have any history with.
Once I got them to replace my gearbox oil even though they said it wasn't needed. With another one I brought them a third-party pedal and asked them to install it. In both cases it did solve my issue by the way, even though I might have been wrong.
They don't care as long as you're ok to pay for the hours regardless of whether it solves your problem or not.
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?
> 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.
There are companies around that offer VIN re-coding by mail order if you need to swap one of the computers, but you'd have to be in a fairly big metro area to profitably run a company just doing electronic trouble shooting. It's easier just to "fire the parts cannon" after the usual suspects (dead sensors, shorted wiring) have been accounted for.
Having had a 2006 model car in my workshop forever rebuilding the engine, I have though it might be worthwhile starting a business doing that kind of trouble shooting but nobody will want to pay, because the vehicles involved are inevitably old and worthless. It's fun to do it for yourself, but as a business your typical customer who needs you won't be able to justify paying you.
My other thought was to possibly set up the tools and whatnot to support local businesses in doing that kind of troubleshooting on older cars but building the knowledge and tools to distribute would be a very expensive exercise.
I love this phrase, and it reminds me that the behavior exists in the computer world too. From the Jargon File:
field circus: [a derogatory pun on `field service'] n. The field service organization of any hardware manufacturer, but especially DEC. There is an entire genre of jokes about DEC field circus engineers:
Q: How can you recognize a DEC field circus engineer with a flat tire?
A: He's changing one tire at a time to see which one is flat.
Q: How can you recognize a DEC field circus engineer who is out of gas?
A: He's changing one tire at a time to see which one is flat.
I've toyed with that kind of thought. The technical part seems fun, finding customers (especially the first customers) seems difficult :p I'd really like to work at such a company though.
Actually had this problem in PC repair. A lot of times I'd spend hours/days diagnosing an issue just so I could understand it inside and out and have a quick solution for the future. I could almost never bill customers for it since it would've cost hundreds of Euros (easily going into 1000+) for what ended up being a fairly simple fix (the $10.000 to hit a pipe with a hammer phenomenon). I'm just lucky I had enough slack to be able to do in-depth diagnoses, because it saved me fuckloads of time later on.
Then there were the cases with arbitrary random bluescreens that were impossible to diagnose where I'd upfront tell them I could only do the bare minimum because otherwise they might have to pay 500 Euros for a solution that probably wouldn't work.
Dude'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!
Ford 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.
I 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.
Aftermarket 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.
This 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.
If 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.
Pulling 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...
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 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.)
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 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.
I wonder if one couldn't identify the time it takes for the battery to get to some low point (50%?) and then determine the order of magnitude draw they would be looking for. 75mA would take a long time (I think) to drain the battery to where starter can't turn over (like a week?).
Yeah, 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.
> 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.
In 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)
Yes I work in automotive and have routinely replaced ECUs. I work for an American OEM, I guess we don’t pair ecus to each vehicle. Unless its ecm/tcm/radio/security gateway and probably the key fob ecu. Everything else is just a part number that you can easily swap out. The few screws holding the controller and the wiring connector(assuming the controller is easily accessible)…
Though I own an Audi and use VCDS I was not familiar with pairing an ecu to the vehicle, however I was aware of coding in the VCDS. (I have not yet needed to swap an ecu on my car)
I’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.
> 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.
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.
Yes, 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.
They use a battery backup. The main symptom of having a dead cmos battery is that your computer starts loosing it's cmos settings, it's a feature not a bug. I have a system where it keeps the cmos config on flash. the only system I managed to brick(almost). I put a bad config in(never disable usb on a laptop where everything is usb) and there was no easy way to reset it. I had to buy a sioc clip and a chip programmer to reflash the thing the hard way.
The point is all cars have a wonderful battery backup system, and resetting the computer when power is lost is also a nice feature.
Yeah, there are lots of ways cars could store such settings that wouldn't be cleared when main battery power is disconnected (which is something that regularly needs to be done when the car is serviced). Flash storage would work too.
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.
Some newer vehicles get upset when you do that, but older ones generally don't. You may lose radio programming though. I've got an old '95 Caravan that's going to be getting a quick disconnect like this one pretty soon though; the drain takes a few weeks to kill the battery, but we don't drive it very often either. Why do we still own it? With the back seats removed, you can easily put 8'x4' sheets of plywood in it.
I did this with an old vehicle taht was pretty basic without a lot of electronics.
the actual problem was sort of electronic-releated - leave lights on, drain battery to zero.
I put on a battery-cutout-monitor-thing. If battery drained to x%, it would disconnect the battery. to start the car, I think you had to stand on the brake pedal (add a load - like brake lights?) and it would reset and reconnect the battery - then you could start it.
this sounds like the sort of perfectly reasonable system that the original manufacturer could install in order to save the world from buying several hundred thousands replacement car batteries every year.
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.
I 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)
It 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.
It'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.
I wonder if this didnt start with 2005 7 series when it received FLIR Night Vision system. That thing was locked down due to ITAR and gave BMW excuse to pair with ECU.
I drive a 1998 Jeep Grand Cherokee. I get asked if I'm interested in selling it at least once or twice a month, nowadays. The sightlines are amazing compared to modern cars, its AC is OP, and the AMC 4 liter straight six is one of the most durable car engines ever made. Mileage is not great, but it's paid for and dirt cheap to insure, that buys a lot of gas right there.
Inline 6 has to be one of the best engines. I got 3 cars with them in 4L, gas injected, gas carbureted and diesel. They go so well.
The only computer in the diesel one is the glow plug timer and there is no computer in the carbureted one (both 1991 Nissan Patrols).
The injected one is a 2005 ford falcon and is starting to get all sorts of interior electrical niggles. Only wiring issues in the patrols is a left headlight short which was easily routed around using relays.
Nice, I had a 97 Jeep Grand Cherokee and it was a great vehicle. I did have a problem with the doors falling off, which I think was a defect at the time.
At 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.
Yeah, 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...
I 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.
After my Audi I learned I'm never buying another German car. Hard to work on myself, absurdly expensive for the shops to work on them, parts are very expensive. Since most owners seem to be "of a demographic" that does not mod/repair their vehicles, the online community pales compared to some other brands where this is a bigger part of the ownership culture, IME. Yes, I know there are passionate Audi modders and repair forums out there, but I'm referring to a percentage of the ownership base and in comparison to communities around other makes.
The Audi was great fun to drive though, no denying that. Just different priorities in what I want out of a car.
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)
That'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.
Agreed - the last 5 that felt good to drive was the e39, and the rest probably peaked with the e90 or e8x. I felt the same way with the corvette - my c5 was the most fun to drive. C6 was an upgrade in comfort but significantly number, and the C7 was horrific. I took a C7Z for a spin and it felt slower and more boring than my c5 despite having 2x the HP.
Sterile 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)
I agree it may be 90% as fun to drive (which is subjective), but you're comparing FWD to RWD.
I'd much rather have a 80's-90's Nissan or Subaru, especially built, than a modern BMW, though. Much more soul in vintage cars imo.
Some vintage BMWs were pretty reliable, a lot of modern Nissans have awful reliability.
It's AWD, but the MS6 has about 100% the repair bills of any old BMW, this person just has no idea what they're talking about. Maybe they owned one when they were new and doesn't realize what long term reliability is like
As 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.
As a former E46 and current E83 owner, my advice is go for the earliest chassis code you can find while keeping mileage low. You need to find a unicorn at this point. (Unless you like turbos - then you have to go E90 or newer.)
BMW really ramped up the electronic complication starting with my E83, and that shit wears out right alongside all the typical flimsy BMW plastics and rubbers. Plus the delightful parasitic drains from tfa.
They also ramped up their maintenance-unfriendly designs around the E46 era. On an E39, a rear spring swap is easy. Try it on a newer one, and you will regret the attempt.
Anecdote. I've had a BMW for the past 9 years now, and not once have I had to open the hood of the car or so much as replace my wiper fluid. I don't even know where the lever for any of that is. I pretty much take it in to a dealership when a light on the dashboard lights up, they drive me to work, pick me up after and my car is good to go.
Agreed. I beat my C5 and C6 pretty hard, but aside from (some) of the GM/F cars you’re very limited in choice. Especially if you’re looking for a lightweight sedan.
Good 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.
I'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.
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.