Jeedie

Oh dear oh dear... I've gone and replaced the HPFP with a MB original one, the Bosch part number is ever so slightly different which led me to take the change. The non-MB part has part number 261520217, the MB part has number 261520218. Unfortunately, this has not made a single difference. Well, at least I know stock a spare HPFP if I ever need one.

Anyways, it seems all parts in the fueling system are then okay. I checked the low pressure twice, checked the hard lines for any blockage, checked the wiring, checked the solenoid PWM signal etc. etc.

What I end up with now is by itself interesting. During cranking, I get a solid pressure build-up. As soon as the car starts, the pressure drops immediately. This is what you see below. This pattern is similar now on any startup.



So now I've got to understand what triggers this drop. As far as I can see now, it's not related to either of the pumps or the pressure sensors. The quick rise during cranking would proof to me that, if controlled correctly, the pump just works. Further investigation commencing. Camshaft phasing acting up, trowing the HPFP solenoid control out of sync with the cam lobes? Injectors opening too long thus losing pressure? I feel another session coming up with my new picoscope.

Jeedie

Battery level got too low for further testing, preventing an actual engine startup. Which did show this graph for fuel pressure (notice the low voltage in the top left corner...):




So this is cranking twice, without engine startup. The engine cranks for a very short time due to the low battery charge. Sorry for the lousy quality, I took a video in HDR, which is very hard to get a good screenshot from.

S-Prihadi

Damn......... that is bad news for MB genuine HPFP still not able to pressure up to 180 BAR.

You better get a 20 amps battery maintainer, set at 13.2 - 13.4 volts, so no discharging will occur and only so very mild charging will occur, less than 2 amps and can be zero.
When ignition is ON, all light off inside the car, daylight OFF, its about 9 - 10 amps for my car.

Lets wait for your crankshaft waveform/signal and intake valve VVT waveform at the same capture, otherwise its hard to proceed because
we now are looking at probably some missing data input for ECM to properly boost up fuel pressure.

Jeedie

Yeah, I have to wait a bit to charge the battery and then I'll get some readings of crank and camshaft. When you save Intake Valve VVT, is that the control Y49 solenoid or the hall sensor? I suspect the last one. Also, do you happen to know if the camshaft position ring is fixed to the camshaft or the VVT adjuster? E.g, once the VVT starts operating, is the camshaft hall sensor showing changing offsets to the crankshaft?

For sure I have to get a better charger, the current one is maybe outputting 1A, way to little for all these tests :-)

CaliBenzDriver

Indeed the camshaft position wheel is loosely pressed on the camshaft itself. That generates correlation faults when time is ripe. You can check positions at 53° crank position +/-360° turn.✌️

I think @S-Prihadi is spot on with idea of bad data upsetting the ECU into shut down.


I guess the question we need to answer is:
​​​​​​> WHY is the engine unable to build up high pressure with new pumps ?

Now we are scrutinizing camshaft timings affecting pressure - HPFP is driven by Bank1 Intake.

> What kind of ECU data can help point us to a broken condition? ECU meets a condition that says: "abort start sequence"!

> ECU disabling the proportioning valve could starve HPFP, right? (Apparently that's what is happening!)

> Do we know for sure HPFP control logic is timed with cam lobe position ??

Jeedie

Are you sure it's on the intake cam? It's a M276 engine with the intake ports in the middle of the 'V'. I would say the HPFP is driven by the right side exhaust cam.

I think the pump itself is more than capable of creating the necessary pressure. During cranking, it gets to ~700psi in maybe one or two turns of the crankshaft. I'll have to validate this with the scope once the battery is charged.

As soon as the engine starts ignition, the pressure drops, just as if the opening / closing of the quantity valve is at the wrong moment.

So far I can only think of a bunch of sensors messing up the ECU's idea of cam position. Either crankshaft hall, camshaft hall, faulty solenoid in the cam phaser. Any other sensor inputs I should examine?

CaliBenzDriver

Ok, until we can fish the right ECU data we can still make some progress:

1-- Number your cam sensors and switch them around bank1>2, Intake> Exhaust - They are all identical.
I would totally leave alone the VVT Solenoids.

2-- Do a 53° degree cam wheel check ( see YT Video at bottom) when you have cam sensors popped out


FYI:
Bank1 (US Passenger side) EXHAUST camshaft has the PCV diaphragm attached to it.
Bank1 INTAKE cam has the HPFP 3 lobes for NA, and 4 lobes for TT.


> Rail Pressure sensor:
Any chance we can gently wiggle the rail pressure sensor harness while looking at data - Engine OFF reads the low pressure side. This helps us diagnose the sensor is functional.
Have a look how tight is your harness hanging on sensor. My driver side harness was pulling hard on the rail pressure sensor. I eased the harness around before reinstalling the plastic intake plenum.


My No1 suspicion is a flakey rail pressure input causes ECU to shut off HPFP control valve - Harness connector or sensor.

Hopefully it is painless.
🤞

++++ let me fish the YT Video 4 ya....
Here is Master Tasos video
This shows if you can trust the loose timing wheels have not moved too much.


After this if you have not found the smoking gun, then it will be time to comb Xentry for evidence.

Jeedie

Thanks a lot guys, another bunch of useful ideas that I'll try. Your feedback is really welcome, I'm comfortable working on cars, but the complexity of this mercedes is beyond what I'm used to. I'm learning a lot, that's for sure!

Regarding the high pressure sensor, I've already renewed this one, as the first codes that showed up pointed at a faulty sensor. 'P019017: rail pressure has an electrical fault. The limit value for electrical voltage has been exceeded.' This error has not returned, however it could well be that, due to the very limited amount of engine running (it will stop within 10s), this error could still show up later. I'll check these wires.
Oh, and very useful that I have to look at inlet camshaft timing, I've been looking at various exhaust cam info thus far, that has been useless then . Ah well.

It would see that disconnecting the VVT phaser on the front of the engine would not allow the VVT system to work, and it would lead to the infamous catch bolt to keep locking the cam timing, keeping the cam in a known-good position. Would this make sense to try?

CaliBenzDriver

No worries... we are all learning! Help is always nice when in trouble.

1-- I would leave both the VVT and solenoid alone. I don't think ECU shuts down engine when these two go wonky.

2-- It's super interesting this ordeal started with bad pressure sensor code....
It would make sense ECU quits pumping not knowing what pressure it has reached.

You have new sensor already... then let's GENTLY wiggle undersized wiring harness with key=On, Engine=Off - Observe the pressure data value equals low side pressure... wiggle, wiggle then unplug to confirm you get a live fault.

Any evidence of "oil in the harness" at ECU plugs??

Jeedie

Busy testing and probing the various suggestions, one thing that really stumps me so far is the reading I get from the crankshaft hall sensor. I get an exhaust camshaft hall sensor signal on the crankshaft wire in the ECU connector. This is an example of sensor B6/7 (right hand exhaust camshaft) combined with B70 (crankshaft):



So I can find a total of 5 pins on the ECU connector with a valid pattern for a camshaft hall sensor. Totally puzzled now. I'll see if I can disconnect the actual camshaft hall sensors to see if this signal disappears from the crankshaft sensor.

Oh, and I've been doing some asking around on the history of the car. There is a suggestion that part of the wiring loom has been replaced due to an oil leak in the past. Hmmm... The ECU connectors are bone dry, not a trace of any oil. Same goes for the various camshaft connectors. Not sure what to think of it, the engine loom looks very original to me.

The vehicle loom connected on the ecu does have some weird tape around it for the first 15cm, maybe someone worked on that bit?



This is similar to my car, the harness is indeed putting quite some strain on the sensor. I'll execute the wiggle procedure as suggested.

S-Prihadi

wow wow wow

J wrote : Last week I bought a used 2013 S212 E300, with the 3.5 M276 engine. All seemed fine and a throughout technical inspection performed by Dekra showed no issues with the car. So I bought it in confidence it was a fine car. However, on the second drive I ran into issues when starting the engine. It misfires badly, won't rev, smells like unburnt fuel and even lacks the power to drive at walking pace. Pretty bad.
How far did you test the car or has driven the car during 1st drive ?


What pin numbers both of them.... did you probe for Crankshaft sensor ? Would be under M connector, the 96 pin one. What wire colors are they ?

S-Prihadi

B70 Crankshaft position sensor and B6/7 Exhaust Cam Position Sensor , their signals are next to each other



Both sensors are 5 volts pulses.

If say wire jackets of pins 82 and 83 are wounded and the copper strand are shorted together.......... the signal would not look so clean as a CAMshaft position sensor being solo.

S-Prihadi

That is Tessa branded tape, not electrical tape per se. Is it more like cloth or fleece ?



EDIT / ADD
This is abrasion resistance Tesa tape
.
Cloth like





===============

This is noise reducer Tesa Tape


Noise reducer. fleece like

S-Prihadi

Why don't you remove your ECU, place it connector down on a table for 24 hours. So if say there is oil inside, hoping it will leak out to the table.
In M276 3.5NA ECU installation is connector side facing sky up right ?




My engine the ECU/ECM is flat, level installation at middle of V bank



.

Jeedie

Pin 59 and 83 on the M connector, colours matching the diagrams you uploaded. 59 Yellow White, 83 Pink. I'll measure resistance between the two, see what that gives.

Test drive was circa 15 minutes by the German 'Dekra' organisation, they perform vehicle inspections. They also performed an OBD check, which showed no errors on the ECU at the time. I did a 5 minute drive that was fine, before it stopped.

Jeedie

Wiggle test of the HP fuel rail sensor has passed. Live data is visible, as just after the engine stops, I get a steady pressure decline for a while. So that one seems to read okay.

I measured resistance between pin 83 and 59 (crankshaft and camshaft hall sensors), and this reads slightly below 1Ohm, so way too low. I then disconnected the hall sensor from the exhaust camshaft left side, which made the crankshaft sensor signal completely silent when starting the engine. Something very fishy going on here.. I disconnected the ECU connector and measured the resistance again, and it's now at infinite. Hmm, a short within the ECU perhaps?

Then I further examined the engine loom and vehicle loom. This is the suspicious bit on the vehicle loom:




Hmm, that's doesn't really look all that original to me.

Further digging, this label is attached to the engine loom, close to the oil filter housing:


That's interesting, the date stamp is 11.08.15, while this is a 2013 vehicle. So okay, the engine loom does not look brand new, but it must have been replaced in the past. That must have been an expensive job for someone!

Then onto the ECU, to start the '24h drip test'. Now I begin the have some more insights into the history of the car, as I found this on the bottom of the ECU:



Someone has been in there fairly recently, the date stamp shows 15 February 2023. Last vehicle service, as reported by Mercedes Benz digital service history was performed on 18 April 2023, at only 400km ago.

Right, so there must have been serious issues with the car in the past, probably years ago when the engine harness was replaced. I think years ago as, examining the state of various connectors, they do not look 400km old, they are too dusty / greasy for that. Then recently the ar must have had troubles and someone had a go at the ECU. Looking at that seal, it's probably a warranted job. And then the car has these issues 400km down the road when it's in my hands.

I think I'll try to trace the shop that put that warranty sticker on and ask them some questions on the work performed...

CaliBenzDriver

Great detective work!
You've found the proverbial smoking-gun

So you got sold a defective car that could not get repaired - Repair were done improperly, now you have a hard failure on exactly what was worked on before sale.

It seems indeed you had a case of "oil in harness" with repairs done to wiring harness + ECU Overall surgery repair.

What do you want to do ??

1. Back track the purchase, return this car.
2. have them fix it, keep this car.
3. Eat the repairs and enjoy the ride

Computer having been repaired once would warrant a second chance to get it right -Or replace with a known good used/new ECU.

It sound that mechanic may crossed sensir wires during harness replacement - This type of work likely done at the big house... a local MB dealer!
Work done on VIN# is well documented within MB Organization - You should be able to find out who did what when... do you still need to work on it??


++++ "oil-in-harness" $8k topic :
if you decide to keep this vehicle, we can help you simply prevent repeat "oil in harness" ordeal:

• Renew plastic sensors at camshafts: CPS
• Install disposable pigtails as insurance
• Delete low-oil cooling: the root cause!

Jeedie

Great question that I spend part of my night on instead of sleeping

I got this car via-via, partially through trade, and it will be hard to back-track or get warranty on it. I imported the car as part of this history so it would be really really hard to get anything. At the same time, it's a brilliant spec car that I got for a very good price. Knowing warranty claims would be very difficult, I decided to negotiate a very low price to allow me ample budget to work on the car if needed. It's also why I had the independent 'Dekra' organisation in Germany perform a vehicle check before I bought the car, that gave me a good understanding of the state of the car.

I know the car ran well until very recently, so it's fixable, it's just that the fix wasn't done in the right way. So for now, I'm nudging into the 'repair it myself' direction.

Indeed, I already found the company that provided this ECU and they do warrant their work. I'll get into touch with them today to see if I can find the original fault on the car as well as the name of the workshop that offered the ECU for repair. It would be very useful to me to get full insight in the work that has been done so far.

Good idea, I'll call my local MB dealer to see what they can find on the history of the car, not just the service history which I already got.

The idea that wires where crossed cannot be ruled out, however it seems it's an original engine harness of the right type (MB number matches the harness needed for the car). So there would be no need to crimp any connectors onto the wires themselves. The colours of the wires match the wiring diagrams of the car so far, including the wiring to the various sensors. I'll see if I can visually inspect the connector on the crankshaft sensor.

The lack of a proper crankshaft signal to the ECU should not be too hard to trace and fix, expect for the fact that the sensor itself is buried deep down the back of the engine.

Yeah, that makes sense. The sensors at the camshaft (hall and phasers) are clean and leak-free. So either they were not the cause of the leak, or they have already been replaced. The pigtail wiring is on my wish-list, but before I start changing things on the car, I want to have it running fault-free.

Low-oil cooling as root-cause: please explain this? I've read a fair bit on the known issues with this vehicle before finding and buying one, I think the first check I performed once I had access to the car was to check the camshaft sensors for leaks ;-). Low-oil cooling issues is something I haven't read before, what would be going on?

CaliBenzDriver

Master Surya knows 200% about all of this

I have to get my daily-driver ready for early Am driving.

You're in great hands - Decisions are yours.

Jeedie

Just got off the phone with the garage where the last repair was performed. The ECU was already repaired by then, or at least they are not aware of an ECU fix. They found a coolant hose above the crankshaft sensor leaking, which led to oxidation on both the crankshaft sensor and connector. They replaced the coolant hose, the crankshaft sensor and the connector on the harness. The car ran fine after this fix. There was no further oxidation found on any other connections.

So that overlaps nicely with the finding that there is no signal from the crankshaft sensor / or a duplicate camshaft signal. Now I need to find a way to better assess the crankshaft sensor wiring, it seems the sensor is not really accessible at the rear of the engine.

More and more, the cause of this whole mayhem seems to be relatively small, just with a complex impact.

S-Prihadi

Its coming to better light the issue now.
How many KM have the car actually done ?

Item 1, coolant hose & pipes. Now my worry of it has proof that it will leak or snap. I will replace 3 of those items next year, 10th Bday of my car. Yes 3 items, not 1.
From engine block to heater core of HVAC, total 4 items actually.

Plastic Pipe 1 & Pipe 2




ABOVE : PIPE 1


BELOW : Pipe 1 and 2



Hose 1, plastic pipe to intermediate firewall ( heat shield ) is item 180 above EPC drawing. Below image is for my 3.0 Turbo, 3.5NA could be different.





Hose 2, from intermediate firewall ( heat shield ) to HVAC heater core is item 150 above at EPC drawing. Below image is for my 3.0 Turbo, 3.5NA could be different.





========= ITEM 3, crankshaft connector of wiring harness ==================
If they replaced it, it is a DIY job. I hope they also replaced the female tin coated terminal + waterproof seal, because buying the plastic connector does not get you the female tin coated terminal + waterproof seal


Above is for my engine, you need to verify for your engine.


.







Above is for my engine, you need to verify for your engine. https://webautocats.com/epc/mercedes...asis=212255D24


==============================



Usually if complete wiring harness of ECU/ECM di renewed, it is the famous oil leaking out of the cam-pos-sensors and the VVT magnetic solenoid, so total 4 + 4 = 8 suspects
If the leak is really ignored, the oil then goes into ECM and start making all the weird issues which does not make sense.
While oil is electrically insulating WHEN NEW VIRGIN, used engine oil is not isolating oil quality/grade in electrical speak and can cause mild short circuits.

The only time I renew an ECM was on my friend's M271 C200 W204.
It was an intermittent misfire which does not occur all the time but will happen if car driven up to 1 hour.
This is not oil contaminated ECM issue, this is a ignition related component failure inside ECM, maybe ignition chip or ignition driver/s, I do not know.

At the least your scope has done its proper duty, which is to see CRANKshaft waveform of yours was not there and instead an Exhaust Cam-Pos waveform you got.



=====================


Now it make sense why you are having issue with your B4/25 Fuel Rail Press + Temp sensor
B70 CRANK-pos-sensor and B4/25 are the only 2 sensors which is specially fed by the very same power source, called Z7/41z1 Sensor Power Supply Connector Sleeve, a splice actually.
See below : Pin 44 (-) and pin 19 (+). Most likely a 5V power output, which fuel rail pressure sensor requires.




So that flooded CRANK-pos-sensor could be the initial problem to why the driver/power supply of these two sensors may act up for short circuit defense purpose, or/and finally get damaged from the short circuit some hours
later after the repair...........assuming the wiring/connector repair of Crank-Pos-sensor was done properly.


.




.
Both IN and EX Cam-Pos-Sensors both at Bank 1 ( right side ) is powered by Fuse 23 and that is a confirm +12V.




=====================



Your initial DTC was too generic, what was the real complete DTC MB version ? Our engine is MED177 ECM, so its DTC database woud be very very similar.



Above and below are all DTC related to our MED177 as per Xentry.
You can see it here : https://mbworld.org/forums/e-class-w...code-list.html





.


.



=======================


Actually you can now after the 24HR oil drip test out of ECM, do a power supply check at ECM for B70 and B4/25
01. Do not connect connector M the 96 pins one to ECM.
02. Only connect the F connector, the 58 or 56 pin one to ECM.

With ignition ON, engine OFF, read pin 44(-) and 19 (+) at ECM male terminal, connector M.

You see, some sensors/components are powered by ECM, and surely the 5V ones because ECM need to regulate 5V sensors internally.
The 12V devices and sensors, many are direct fused powered from Front SAM N10/1 Fuse Box.
For M276 3.5NA, 5 fuses powered the ECM and all its sensors/devices.

Okey, happy troubleshooting.............


==========================

The sequence of events probably is this way :

01. Oil leaks into ECM connector may not even be the problem at all, to begin with. Maybe.

02. The power supply or driver of B70 and B4/25 at the ECM has intermittent issue from that flooded CRANK-pos-sensor.
As to how good the repair was........ I can't comment. All we know now is you have issue related to it, AGAIN.
As to why the signal of B6/7 can get into B70, most likely the ECM internal is now the problem.

03. It is quite logical flow-chart of thinking, that when one has DTC related to Fuel Rail Pressure sensor, the other related component is the HPFP pump then becomes the focus.
Hence that broken connector, from a frustrated techy as the HPFP fuel pump shroud/shield is no fun for removal.

04. Very likely the shop did not use a scope to do the deep investigation and believed too much on DTC info alone.
Anyhow, even at Pico scope forum, there is no waveform of the HPFP available and most people do not understand how HPFP is to be pulsed when and if using such cam lobes and
hence do not know what kind of waveform to expect, even when scoped. You are lucky I have the waveform of a healthy ECM pulsing a healthy HPFP.

===========

AA. Now you would realize, if I did not push you to scope your CRANKshaft-pos-sensor, this troubleshooting may have gone extra few days.

BB. Our modern engine management system is very complex. Designer/engineer write special parameters for WHAT IF scenario which not all are explained in MB WIS.
Our best hope is to learn more of the engine while it is in good health.
An ECM outputs or commanding of components actuation, are only as good if it get proper inputs.
So verifying inputs are good, is always no 1 priority. No more the input is a simple 12V flat DC signal like older ECM.
Having a scope, a lot of work to scope and measure this and that when engine is still healthy, but we gain knowledge and cut troubleshooting fast when we one day get into issues.


CC. By now you realize a 2 channel scope is not enough...right.
I too started with 2 channel Pico 2000 series like yours, the 8 bit.
I got frustrated when doing my friend's M271 troubleshooting and after that learning, I ended up buying the 4 channel 4425A automotive version Pico floating ground to 30V and is a 12 bit where
this 12 bit can make or break the troubleshooting , when we come across certain issue needing the resolution of 12 bit.

Our car is a V6, a 6 channel scope is the minimum better tool, but too bad Pico 8 channels scope is NOT a floating ground unit.
Just for BANK 1
VVT actuators solenoid = 2
CAM Pos Sensor = 2
CRANK pos sensor = 1
Ignition of cylinder 1 = 1 <<<< Total is 6 channels just to be able to see these and if only we have 1 more extra channel for 1 more device/sensor, it will be gold.

==================


PS
The Oil thingy Cali mentioned is how we defeat the lowered oil pressure below 3,500 RPM our engines are designed to do.
Our oil pump has a solenoid to reduce oil pressure on purpose under 3,500 RPM in the name of fuel efficiency from less pumping of oil
Thus your intake VVT sprocket will wear out early than it should and will make the stupid rattling sound, some under 100,000KM or much less.

Jeedie

100.000 KM so far, so it’s had an easy life. With nice yearly service intervals, so relatively fresh oil etc. Which is a nice plus. And the coolant pipes which don’t survive 10 years have at least been replaced :-D

I’ll have a go at getting at the connector and sensor, see what they actually replaced.. If they reused the terminals that would be very odd, but it would explain a lot..

Wow, there is an actual splice somewhere in that short bit of wiring loom, I didn’t expect that! But it would make a lot of sense, especially if coolant has made its way up into the wiring, just like oil creeps through the harness. The spice is the first victor if this would happen. I’ll try to find it.

Funny you found that B4/25 fuel ‘tank’ type in the pdf as well, I noticed it too earlier this week. Would really upset troubleshooting if you see 200bar in the fuel tank.

P019017, so the second screenshot matches, electrical fault, limit value exceeded. So maybe a short from the signal to the 5V, as a hall sensor should always be below 5V? Anyway, it is pointing at the same pin 19 used by the crankshaft sensor.
Together with: P008800, P008700 and all possible misfire signals.

[QUOTE]
With ignition ON, engine OFF, read pin 44(-) and 19 (+) at ECM male terminal, connector M.
[/QUOTE

I’ll check and give feedback here.

Oh absolutely, thanks a lot for that direction! Remember post #68 en #69, where I showed the signal from the crank and you correctly did not recognise that blue line as a crank? So good to have known-good references, otherwise I would have continued believing that cam signal was actually a valid crankshaft signal..

I’ll make sure to get a valid crankshaft signal somehow first. There are multiple things I can think of that could lead to this signal replication, even the ECU doing this on purpose to get a ‘substitute’ signal on that pin. Funny thing is, I measured conductivity between pin #59 and #83 with the ECU connected. Now that the ECU is out of the car, I cannot replicate that conductivity, neither on the ECU side nor the connector side. That could indicate that it’s actively switched internally by the ECU. I’ll try to replicate this when I reinstall the ECU.

Not yet ;-) For now it is sufficient to check the various signal, and to check if they are in sync. As long as I have a single, known good, reference, I can reference other signals from that one. It’s more work but it gives me enough insight (for now). If the car eventually runs, I may not touch that scope for a few good years (fingers crossed).

Ah, that bit I found, fixed partially by the check valve right? I misread that oily thingy as a root cause of the oil leak into the harness, that puzzled me. Now it makes sense.

Oh well, onwards with the troubleshooting / repairs. With the info I got today, I feel much more positive on a relatively simple solution. Finding a seal on my ECU yesterday made me suddenly question my sanity in buying this car, but if it’s fixed properly, all should be fine.

Jeedie

Oh, I just see on the diagram that the ground is also shared as Z7/44, so there are multiple shared paths. What kind of solution is used for these splices in the harness? Soldered or crimped connections? Have you found any of these before in your wiring?

CaliBenzDriver

Great question!
The harness splices are reliables but you can count on marginal GND to provide opportunities.

Splices are both crimped and nicely soldered: great !


MB builds (W212) GND circuits to be amazing - They generate unstable voltage in reference circuits (LIN!) and surges in the power circuits (LPFP, chassis strap!).
That chaos provides a nice showcase for differential CAN signals partly immuned to glitches.


> The only two good GND I know are located on the engine valve covers -
> Other than that, all those GND dealing with chassis posts use painted nuts and oxidized posts... ouch!
Fixing ... Front footwells Trunk sides, Front beams are great ways to boost overall module reliability on these chassis.

Practically trace the schematic to learn where GND splice hits the engine/chassis
-- Clean that shared GND point.
-- Then go clean your main "chassis to engine" strap.

✌️

Jeedie

So, it was a bit of a hunt to locate the crankshaft sensor. Eventually the easiest way for me was from underneath the car. This way I could remove one bolt from the heat shield hiding the sensor, then bent the heat shield slightly open, to find the sensor.

The connector is an original MB part, with new terminals. I checked conductivity between this connector and the ECU connector. That bit checks out okay (surprisingly!). Also I cannot find any shorts between B70,B4/25 and B6/6 . Of course, I'm moving the wiring around to test things, so that could influence this.

Next step would be to validate the source of the issue with the crankshaft sensor signal. I can either try to unpin terminal #44 from the ECU, so I can scope the crankshaft sensor without giving the ECU a change to interfere, or I could run the car with a disconnected crankshaft sensor to see what that would show on the ECU side. I prefer the first option, as if that would still give no crank signal, I can just move onwards to installing a new crank sensor (which seems to be possible from underneath the car as well).