Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

BMW F Series Gear Selector, Part Two: Breakthrough

projectgus.com

Post reply on HN
Print view View original

61–70 of 118 posts

Re: BMW F Series Gear Selector, Part Two: Breakthrough

#61

Post by quarantaseih »

Im currently renting a BMW with this gear selector.

In fairness, I throughly hate the car (an X1). Terrible lag, awful throttle response, terrible steering, unpredictable brakes, etc.

But the two candidates for worst feature of the car are

1. The gear selector 2. The indicator lights

Every time I have to engage one of the two I let out a little curse.

I driven stick shifts, autos, rear wheel drive cars, trucks, front wheel drive cars, uHaul trucks, and manual motorcycles.

Ive off-roaded in CA, driven through blizzards, Mediterranean traffic.

This is by far my most hated driving experience.

Re: BMW F Series Gear Selector, Part Two: Breakthrough

#62

Post by themitigating »

bri3d wrote: post #46
themitigating wrote: post #27

Earlier quoted context omitted.

Mostly every component on modern cars uses the CAN bus for communication https://en.wikipedia.org/wiki/CAN_bus Many third party companies have made accessories to read information or control devices using it. Cars also have a standard diagnostic port called the OBD2 which you can purchase $10 readers that use bluetooth with your phone. Cars may have much more electronics but with all the sensors it's very easy to kno…

Saying "most cars use the CAN bus" is kind of like saying "the network uses Ethernet," though - the higher layer protocols are usually proprietary and one-off for a specific vehicle lineup. Even the standard diagnostic protocols like UDS rapidly become non-standard once you get to the "what's what" level. For example, $22 readLocalIdentifier is standardized as "read local identifier," but what each identifier means i…

You are correct, I was only thinking of diagnostics.

Re: BMW F Series Gear Selector, Part Two: Breakthrough

#63

Post by waiseristy »

asciimike wrote: post #11
wolrah wrote: post #6

Earlier quoted context omitted.

> Makes me want to go out and hug my truck, whose gear selector consists of metal sticks and pins. If it's a manual transmission or an ancient automatic, sure, but manual transmission trucks basically haven't existed for a decade or so and every automatic since the mid 90s has an electronic gear selector of some variety. Somehow the world keeps working just fine. The biggest problem that's come up with them has been…

2021 Tacoma Manual owner here (one of the reasons I got it). Gladiators and Broncos are also available with a manual!

For the Tacoma, you made a good decision. The auto in that thing is the single worst programmed automatic transmission I have ever encountered. But that doesn't just automatically apply to all OEM's. There are plenty of autos that are great & responsive. Fords 10 speeds are quite good.

And you only got rid of 1 of the dozens of computerized components in your drive train. Your engine, transfer case, rear differential, and hubs are all computerized

Re: BMW F Series Gear Selector, Part Two: Breakthrough

#64

Post by rconti »

phkahler wrote: post #44

A lot of the complexity here is because the gear selector is considered a safety-critical part. They may also consider LED indicators on it as safety-critical information to the driver. Those two things - is the transmission receiving the real intent of the driver, and is the driver being told the actual state of the system - are just the top level. Security is also starting to be a concern, though I think there is r…

Yup. Bad Things can happen:

https://money.cnn.com/2016/06/20/autos/jeep-recall-anton-yel...

I absolutely hate stateless switches on automotive stuff. Why can't I tell that my turn signal is on by 'feel'? Why do I have to rely on a (too quiet) clicking, or a (too hidden) indicator light?

I have an E70 X5 with the "new style" transmission selector, as well as a Tesla 3 that replicates it on the right side of the column. Thankfully most cars seem to have stuck with the "forward = reverse", "Back=drive" convention; confusing as it sounds, at least it replicates a move from neutral on an automatic with a traditional PRNDL lever.

Both cars also have stateless signals. The E90 and newer BMWs seem to have indicator clicks that are almost inaudible, and in almost every car I drive, the indicator lights are hidden behind the steering wheel, so you never know if the indicator has cancelled or not. On my "bad old world" BMW, at least you can feel the lever click down when it cancels.

The Tesla also has a stateless signal switch, but it doesn't give me the same issues. I think the audible "click" is a lot more distinctive or something. Alas, the green flashy light is way over in the middle of the car instead of conveniently hidden behind the rim of the steering wheel.

Re: BMW F Series Gear Selector, Part Two: Breakthrough

#65

Post by asciimike »

bonestamp2 wrote: post #54
BoorishBears wrote: post #45

Earlier quoted context omitted.

If you're comfortable with slightly shadier methods, there's "grey market" access to most BMW tools. With the F and G series ISTA is the "gold standard"

Can confirm. I paid a guy on a BMW forum about $100 for the vehicle interface, which is ethernet to a J1962 connector (aka "OBD II Port"). That also included the e-sys software (Windows only). A few years later I needed an update to the software and found a guy on ebay who charged me about $75. So, those might be some places to look for this kind of thing.

The OBD adapter should be cheaper nowadays; most folks on the BMW forums will charge ~$100 for coding services, and it's generally "any time you need anything changed, it's free."

If you're in the bay area, there are a few local folks who are happy to do it!

Re: BMW F Series Gear Selector, Part Two: Breakthrough

#66

Post by Rychard »

londons_explore wrote: post #32

Hooking it up to a real car and sniffing the message bus where it connects would be by far the easiest approach to this... Then you don't even need to understand all the messages - just replay what the car sends and figure out which byte in the response is the current gear. You probably wouldn't even need to figure out the checksums!

The messages include an incrementing counter ID, which has to be accounted for when calculating the checksum. The purpose of this is specifically to prevent "replay attacks". If the counter doesn't increment on subsequent messages, it raises an error. If you increment the counter but do not recalculate the checksum, it raises an error.

Re: BMW F Series Gear Selector, Part Two: Breakthrough

#67

Post by londons_explore »

Rychard wrote: post #66
londons_explore wrote: post #32

Hooking it up to a real car and sniffing the message bus where it connects would be by far the easiest approach to this... Then you don't even need to understand all the messages - just replay what the car sends and figure out which byte in the response is the current gear. You probably wouldn't even need to figure out the checksums!

The messages include an incrementing counter ID, which has to be accounted for when calculating the checksum. The purpose of this is specifically to prevent "replay attacks". If the counter doesn't increment on subsequent messages, it raises an error. If you increment the counter but do not recalculate the checksum, it raises an error.

The counter is only one byte though - record 256 messages and you have the whole set.

No need to understand the protocol or anything - just record a few minutes of data, find when a message repeats (indicating whatever counter mechanism is in use has rolled over), and replay that loop repeatedly.

The only time this technique doesn't work is when a challenge-response algorithm is in use, but car stuff doesn't tend to do that except for some lock/security/firmware update type functionality.

Re: BMW F Series Gear Selector, Part Two: Breakthrough

#69

Post by Gordonjcp »

paywallasinbeer wrote: post #33
themitigating wrote: post #27

Earlier quoted context omitted.

Mostly every component on modern cars uses the CAN bus for communication https://en.wikipedia.org/wiki/CAN_bus Many third party companies have made accessories to read information or control devices using it. Cars also have a standard diagnostic port called the OBD2 which you can purchase $10 readers that use bluetooth with your phone. Cars may have much more electronics but with all the sensors it's very easy to kno…

It's important to note that just because a CEL is on for a sensor, it doesn't mean that sensor is bad and needs to be replaced. For example, it's possible for a camshaft position sensor to be on for a timing system that is out of sync. It would be a mistake to replace the cam sensor in that scenario. Shotgunning parts isn't always the answer...

Ooooh, I've got a great story about that. My neighbour's car was at the garage for about three weeks with a No-Crank No-Start fault. The diagnostics said that the crank position sensor was faulty, but the garage said they'd tried two new sensors and a new cam position sensor for good measure, and it still wouldn't work. Their next plan of attack - and bearing in mind they were already about a grand into it - was to spend even more of my neighbour's money speculatively on a new engine ECU.

Tell you what, not to be a smartarse guys, but let me take a look, just for a second opinion, okay? It's not cranking, that should be the first clue. No, I bet the sensor is a red herring.

Why? Well, we'll get to that.

First off, why isn't it cranking? I hear a relay in the fusebox clicking when I turn the key, let's swap this conveniently labelled starter motor relay with a spare - rob one from the heater blower in my car - plug it in, contacts look manky and burnt, never a good sign. Oh look, starts, runs, perfect, nice as you like.

No, don't worry about the relay, they're a couple of quid new and I have huge box of spares at home, just keep it.

Oh, but the sensor? Well, the ECU was commanding the relay on to pull in the starter motor solenoid, right? But then after a certain amount of time it wasn't seeing crank position sensor pulses, so it guessed (wrongly) that the sensor was faulty, because why would it guess that the starter motor wasn't spinning?

Re: BMW F Series Gear Selector, Part Two: Breakthrough

#70

Post by Gordonjcp »

themitigating wrote: post #25
h2odragon wrote: post #2

Makes me want to go out and hug my truck, whose gear selector consists of metal sticks and pins. I'd be leery of using this device, with all that complexity, as an input for video games. The latency makes me ugh. Certainly don't want that much "systems" stuff between me and the transmission of a car I'm piloting.

The latency for doing what? Shifting from reverse to drive? The ZF transmissions in BMWs are very fast shifting even though they are torque converters and there are paddle shifters on the wheel.

ZF 4HP22 in my older (4.0 litre) Range Rover, 4HP24 in my newer one with the 4.6 engine. Actually they're both the same age to within weeks, I just got the 4.6 eight years after the 4.0, but anyway - it takes about a quarter of a second to change up or down if you manually prod the gearstick coming up to some bends. It's definitely faster than the R380 manual gearboxes fitted to Discos, Defenders and manual P38s, which needs a fair bit of time in neutral to settle out before you select the next gear.

This is '80s technology, mind you, with a fairly simple computer grafted on to bring it up to the white heat of the mid-'90s.

Post reply on HN