Comments by "Mikko Rantalainen" (@MikkoRantalainen) on "DiagnoseDan" channel.

@pclayton5063 Doing full brake job for 4 wheels may take a lot of time if the car is old enough due rust and you live in a place such as Finland where they throw salt on the roads for half the year to keep roads less icey. I just spend 2 hours getting brake line nut fitting to detach without breaking the line working on our own car. It's interesting how much oxidation you can get between the nut and the lining (the threading was fine!) when they are made out of different metals.
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4:25 Great to see an actual torsion wrench being used to change the wheels. Way too many shops just use impact gun at high power.
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I agree. Typically a second hand OEM sensor from scrapyard is better than new no-name replacement part. Especially for parts such as ultrasound sensors that have no wear parts.
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The margin to 0 and 5 V levels is designed to allow detecting if the wire is (almost) shorted to ground or to power.
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@paulsz6194 Yeah, spare parts is a money well for the manufacturer. However, you would think that they would put diagnostics into the module to make it easily figure out which part to replace. Given that the module reports no errors without the wire connected, you can be pretty sure that they assumed that part to never fail.
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3:45 Note that some high quality scope leads could use shielded cables and that would prevent this tip from working. However, you could use some regular wire around the door handle and connect the scope leads to both ends of that wire.
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As an owner of VAG car, I'm fully aware that scan tool can do nothing without the key in ignition so I wouldn't have even bothered to scan the car when the ignition key doesn't seem to react at all. Great work otherwise and you had some good tips (such as figuring out if the car is trying to talk to the module or the module is trying to talk to the car).
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22:00 It still seems plausible that the actual mechanical part of the turbo comes from the same factory but the servo controller is definitely different!
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15:40 I think some modern cars have variable compressor and can have different pressure delta for different requested indoor temperature. It would have been interesting to see if adjusting the cabin temperature would have affected the pressure delta while the AC was constantly on.
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Great video! I think VAG cars would have stored either something close to "CAN bus short to ground" or "CAN bus short to +12V" for a fault like this – the modules should be able to detect this because working CAN bus should have both wires between +1.5 V and +3.5 V all the time. The fact that BMW modules didn't store better fault code is just poor quality software running in the modules. When you see messages about shorts it's much easier to justify time looking at all the related wiring. However, since all these modules had shared bus wiring for the bus, they couldn't tell you which wire is broken even with better fault code.
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If you just need a good oscilloscope but you're not willing to spend lots of money, check out Red Pitaya. The cheapest model is around $200 https://www.redpitaya.com/Catalog/p57/stemlab-125-10-starter-kit which gets you 50 MHz 2+2 channel 125 MS/s and 10 bit accuracy oscilloscope. Obviously, the Red Pitaya being around 10x cheaper also means that you get zero car specific info from the manufacturer - just a pretty nice oscilloscope.
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@VeteranofthePsychicWars If the design of the module is to trigger interrupt high while the door handle sends the signal (with the intent that the signal is a short pull to ground) the CPU inside the module might be stalled until the interrupt pin is released from the ground. In that case it would be a hardware design issue which causes the module CPU to halt until the ground is released and it cannot be fixed by software patch.
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9:30 VAG car has a broken microswitch, news at eleven. VAG cars have nearly always at least one broken microswitch in one of the locks in the car and you have to replace the whole damn lock to fix the switch. Obviously, they also designed the car so stupidly that you have to tear down the whole door to replace the lock. In theory it's possible to replace just the $0.10 microswitch but it's buried inside the lock mechanism which requires tearing down the door and the lock. Basically you have to spend 3 hours to replace that switch. Multiply by the amount of doors with the problem! It's well known that microswitches have limited lifespan in cars. How about making all microswitches easily replaceable, VAG?
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14:25 This module is ridiculous! Fails to work with bad door handle and when the whole wire is disconnected (or broken) it still reports "no faults".
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Direct injection engine wouldn't have any carbon buildup with EGR. And the only reason to use EGR is because manufacturer wants to cheap out on DEF/AdBlue.
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@ The margin (0.5 V) applies to both extremes of the voltage range that the sensor uses: 0 V for ground and 5 V for power input. As a result, when the sensor range has 0.5 V margin to all known voltage levels, the usable range for the sensor values are 0.5 ... 4.5 V.
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13:30 ... Or tell the customer that it costs 850 EUR to fix but use the knowledge and repair kit to do it for 40.57 EUR. Profit!
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Great video indeed! I have similar issue with VW Passat and I think the problem is evaporator sensor telling the system to reduce cooling because it things the evaporator is freezing due sensor problem.
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Great video again! I wish the engine control unit recorded a fault when it can see that the key has been turned to ignition and battery voltage is okay but the crank sensor shows no movement in the engine. That should be sure enough fault to be worth logging. It would have been interesting to know if the actual fault in the old computer was just cold solder joint or if the actual silicon had a crack. Re-soldering a cold joint would be a permanent fix but crack in silicon cannot be fixed. However, I have to say that I really don't understand the thinking of the designers! No computer in the world likes the temperatures commonly seen on top of an internal combustion engine so that's really poor location for the computer. In addition, the thermal expansion of the PCB, silicon and solder are not the same for all the parts inside the engine computer so this car is sure to cause cracks in long term use, especially in climates with high temperature changes over the year.
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How come BMW cars always have nearly empty fuel tank? Are they trying to optimize weight?
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2:55 WOW! I thought VAG TDI engines with lots of EGR activity and sulfide rich Diesel fuel had bad build-up but this looks even worse. The "after" image around 14:00 looks quite a bit different indeed.
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Typically the hardest part is to find wiring diagram that matches your car in reality.
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Wow! Are you real that the car was at the dealership and their fix was to disconnect the module? And NOT TELL THE CUSTOMER???
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5:00 You should have mentioned where the carbon comes from. It's from EGR valve that circulates exhaust gas to the intake manifold. Without EGR the only thing moving in the intake manifold would be fresh air from the air filter and that wouldn't cause any carbon build-up, obviously. The EGR system is there to reduce nitrous oxide pollution and if you were to disable that system, the engine would last much longer but the pollution would increase, hence that's not allowed. However, with the TSI engine design, I fail to understand how EGR system could work even in best case in long term. Is this engine type going to suffer from carbon build-up failures in all cases? The interesting part is could you avoid this build-up if you used the revive product during e.g. every oil change. It doesn't seem to remove all build-up but does seem to have some effect and if you were to prevent the huge build-up in the first place, the build-up will grow slower because the air will flow more smoothly. After there's quite some build-up, it will clog even further pretty fast because of high turbulence due build-up in the intake.
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It would be interesting to see if you could make the ECU happy with the aftermarket turbo simply by adding a variable resistor between +5V and signal wire and adjust the resistor to have 0.5V at the lowest controller arm position. Obviously that wouldn't make the part equivalent to real OEM part but it might have been enough to allow the ECU to accept it and run it correctly! Another option would be to build voltage divider between 0V and 5V wires with pretty high resistance resistors to set the voltage but with high enough resistance the controller arm movement would be hopefully tracked correctly above 0.5V level.
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@Diagnosedan How does this car control boost pressure? I have experience only with older VAG TDI engines and those use separate absolute boost pressure sensor and run in closed loop via ECU to control the boost pressure (probably PID controller). The sensor on the vane is only used to verify that that vanes are not physically stuck. However, this all could be totally manufacturer dependant so the hack I suggested may or may not work depending how the ECU is implemented.
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If you use aftermarket MAF in this car, is it going to run the engine lean because the ECU cannot measure the oxygen correctly and will use too little fuel all the time? Or if the ECU uses lambda sensor to adjust the fueling, the same thing there - wouldn't a poor aftermarket part slowly destroy the catalysator?
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I would consider it pretty bad design problem when an input wire getting shorted disables the whole module. Then again, some of those "keyless" entry systems are known to open the door locks on high power radio interference burst - a trick used by thiefs to open those locks. So the poor design in general is widely known already.
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VAG (from Germany, too) has been doing lots of stupid things, too, but as far as I know, even they haven't done this bad design solutions. VAG puts the computer close to the under hood fuse box in a water tight plastic box.
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@Steve Interdonato That or planned obsolescence. If it lasts warranty time, it's good enough for the manufacturer. And you will not see 3rd party engine control units beating the OEM prices so you still have monopoly in spare parts.
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@PaulShalahm I think most people would agree that Mercedes has very competent engineers. Unfortunately, they also have marketing department and when these forces clash, the total output may be less than optimal.
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From the bloopers, it seems that you have similar state as LockPickingLawyer: the hardest part to create a new video is the spoken part: you already know you can fix the car and that's the easy part.
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There was a small mistake in the video. Around 8:05 you show that Fuse 14 is the brownish fuse 4 locations from the bottom but around 9:30 you're testing light blue fuse as "fuse 14". Other than that, great work! I would have expected the wire to be damaged near the connector, not at the "straight" portion of the wire.
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@Diagnosedan Yeah, I noticed it after getting that far.
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If you take a car to Audi or VW dealership and get some results, the diagnose is incorrect with very high probability. The code or the diagnose you get doesn't matter.
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9:20 I would have expected ECU pin for the turbo signal to be bent or broken.
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Did you fix the mechanical locks to match the key? I fully understand the key fob not working with the car without replacing the broken module but the mechanical key should match the doors because the mechanical locks must work even if your battery is dead.
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I guess that would be acceptable behavior if all the modules are still accessible and there's a proper fault for the problem. If they need active engine mount, they probably need that thing. I assume there would be a bumb in the hood if the mount does not work correctly...
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