So the alternator change alone fixed the run problem? Or you only drove it after changing both the alternator and window motor?

I did the window motor first. I still had low voltage after changing out the window motor.

I took the car out for a drive last night and it did great. Voltage stayed up in the upper 13s the whole time.

Note that parameter 24 on the CCU reads low by about 0.7 V, they must have put the sensing past a diode. I confirmed this with my (recently calibrated) Fluke 87 that belongs to the company.

I would have a hard time believing that an internal fault in the window motor would pull the system voltage down to the low 12s without blowing a fuse. The alternator is 115 A and the battery has a 100 Ah capacity.

I noticed the CAN bus issue on the interior CAN after the first time I scanned the car when I got my Xentry last year. The fault was CAN-H shorted to + intermittently. Everything still worked so I kept putting off fixing it. When I decided to hand this car off to my son I wanted everything to work so I had it on the list of things to fix before he heads back to school. He’s a mechanical engineering major at Clemson so he has been a big help this summer. He did most of the work on changing the alternator and he is getting used to navigating WIS and Xentry.

After driving the car for over an hour last night with no issues I came back home and put the computer on it. No faults recorded and system voltage 13.91 V at idle.

Just 2 more system bugs to clear:
- the right side defrost vent does not shut all the way which fogs up the windshield down low on the right. That is an all day project since I have to take the dash apart. Although not nearly as far as when you pull the evaporator...
- the Hall sensor in the drivers seat head restraint adjuster has failed. Forgot to grab one from the 6 W210s that were in the Pull A Part this weekend. Might try taking the motor out and see if there’s a bad solder joint in the sensor first since it’s intermittent.

I was after what was causing the car to shut off. It is very important to understand why something failed and what fixed it.

Reading farther down, I see the CAN high was sometimes being pulled to +. This alone won't shut down the network because the CAN low is still working. Apparently when the car would not run, something was also stopping traffic on CAN low.

For others, CAN is a communication system that uses differential signals. When CAN High has a high voltage, CAN Low has a lower voltage. This increases immunity to noise and a failure of one leg won't crash the network.

Or the displayed CCU voltage is measured at long wire run that is loaded. ( Like with a fan. )

The window motor was not pulling charging system voltage down, it can't dissipate that much energy without a fuse clearing.

See my above, the CAN high fault was a warning sign.

Try explaining to a customer that nothing was done wrong in the recent oil change and a power window motor / controller can keep the car from running. . . "Oh, and you want me to pay for an alternator?"

More importantly, for the home repair guy, is to know where the CAN junctions are so nonessential functions can be removed from the network if it has crashed.

If the hall effect sensor failed open no big deal. However, if the sensor power has failed to ground, it could take out the seat controller / CAN network if it has one. Think about if the window controller was causing a CAN High fault and then the seat adjuster was causing a CAN Low fault causing the network to crash.

If the seat controller is on the CAN network, the car might stop again. " You changed my oil and did something to keep the car from running, sold me a window motor and alternator. It stopped again and now you want to sell me a head rest adjuster? " . . .

I think I finally got to the root cause.

I got it to stop dead again today and it has failed 100% this time. I replaced the transmission cooler flex hoses (one of them was weeping) and so I was idling to bring the car up to temperature to verify the transmission fluid level. And the engine just stopped dead without a warning.

Pulled codes and this time it was crank position sensor and the code will not clear. I checked the technical data in WIS, this is a simple inductive coil (passive sensor with no internal electronics). So I metered it and I have an open circuit at X22 (green connector in the module box) pins 12 to 13 looking toward the sensor.

I had gotten a stored crank position code last weekend when it died the first time. Shouldn’t have ignored that, it was trying to tell me something!

I am going to get into it later and verify it’s not a broken wire and then get a sensor on order. Hopefully this fixes the problem!

I have no regrets replacing the alternator, the one I pulled out looked to be the original. 20 years and 250 k miles, I could feel it was a little rough when I spun it.

Update: The wiring is good. I also tried cranking while viewing live data and the RPMs stayed on zero while cranking. I had all permissives true from the drive authorization and no CAN bus faults.

So I’m still not out of the woods yet.

New sensor came in and I got it replaced. Car started up no problem and I moved it out of the garage.

Couple hours later went to go put it back in the garage and it would not start again.

Got it to finally crank and run enough to pull it up in the garage.

Put it on the computer and it was showing P1335 (crank position) and P0300 (misfire).

Pulled up live data and the displayed RPMs were jumping around various values ranging between 580 and 760 between each scan (about 1 scan per second).

From my observation the engine is not changing RPMs that fast. And I think it would have a hard time actually doing this without violently shaking which it is not.

I proved this using a strobe tach app on my phone looking at the power steering pulley bolts (stand by the LF tire and look at the back side of the pulley closest to the pump). The bolts were holding rock steady when I strobed at the right rate (1518 Hz IIRC) to make them stand still.

I put my Fluke 87 on the signal lines from the sensor (connector X22, the green one in the electronics box, pins 12 and 13) and was reading about 3.8 V ac rms at idle. The frequency was jumping between 55 and 75 Hz. I did the math and realized that the pulse frequency of the sensor was equal to RPM/10. So the sensor is outputting a varying value.

I do not have a scope at hand to verify the waveform as shown in WIS.

I pulled the sensor out again this morning just to see if I had not seated it correctly. I even stuck my USB borescope cam down the hole to ensure there was nothing blocking the opening on the hole. It is possible to remove the sensor without pulling the manifold but you have to be a serious contortionist. 5 mm hex bit on a swivel and 2 x 12” extensions.

I pulled out the new sensor and compared the part numbers. The original sensor (date stamped 20th week of 1998 which correlates with a June production date for the car) has MB part number 003 153 74 28 and Bosch number 0 281 002 124.

The new sensor has no MB number (that area is blank) and Bosch number 0 281 002 123. The sensors look physically identical. The open circuit resistance of the sensor is approximately 1.3 kohms. Production date 5th week of 2018.

I went to http://aa.bosch.sk/download/sensory-2008.pdf and confirmed that the ...123 is the proper sensor model for this vehicle. Scroll all the way to page 224...

So now I’m stumped. Do I have a defective sensor? Unfortunately I cannot put the old one back in for comparison, it is totally open circuit.

I’m about to find a cheap oscilloscope on Amazon or eBay and figure out whether that waveform is correct.

There is also this MB link, scroll down to item 12...
http://manual.startekinfo.com/manual/JSP/de/3_3/m13.jsp

Note the item 5, the engine will just shut down if the CKP is implausible...

Scope on order from Amazon, stand by for update...

Finally got my scope in earlier this week and put it on the sensor. The waveform looks decent and stable and within the parameters as expressed in the WIS. Unfortunately the RPMs as reported by the HHT emulator are still all over the map.

I got with a local friend who has the same vehicle and put the scope on his sensor for comparison. Both waveforms appear identical.

Is the ECU itself faulty? I am at a loss for what to do next.

I really hate to dump this car, it is in great condition and was running great before all this happened.

Is it worth crying uncle and taking to dealer at this point?

Yeah I am about at that point. Going to speak with the service advisor at our local dealer on Monday.

The MB diesel computers seems to have something in common with VW diesels of the same era. ( EDC12 ??? ) Perhaps some VW guys have a similar problem and a fix.

Check the crank sensor wiring for a backed out contact.

Inspect pins on engine computer and plug.

Ohm out crank sensor wires from sensor to engine computer, you can do this the sensor plugged in. While doing this, wiggle the harness along it's full length.

Check wave form at engine computer connector, do this with the computer connected and not connected.

Remove the engine computer, open it up and follow the crank sensor pins to the board, look for a cracked solder joint.

Replace computer with known good part. The anti theft will be tied into the key chip , a reader box and the engine computer so all must match.

I had that thought as well on the harness.

Tomorrow I will try removing the engine harness and giving it a full inspection.

I tried opening up the computer but could not figure out how to remove the board from the casing without damaging something.

Last resort is a new ECU. I have been looking around at the options and it looks like rebuilt ECUs can be had from third parties. Some European sellers offer “unlocked” ECUs, I assume that if I have offline Xentry that I can initialize one of these.

If it comes to dumping this car, I won't mind a rust free southern 210. Hopefully it doesn't come to that, but keep me posted.

Well I had an interesting afternoon....

I got out there after church, 98 degrees today in SC, at least I’m in the garage with a couple big fans.

Got the intake manifold removed and the wiring harness removed. Really not all that difficult. It runs from the green X22 connector plus the one purple wire for starter from the control box, around the back of the engine block, picks up the starter, CKP, all 6 glow plugs, coolant temperature sensor, intake air temperature sensor, fuel valve, and oil level switch, and then another connector to the glow plug relay. Easy peasy to remove.

Discovered the fuel shutoff is weeping diesel out the connector port which explains the diesel smell I had been getting. Once I got under the manifold I could see the DVs are dry.

Got the harness spread out on the garage floor and inspected it. Wiring looked to be in pristine condition, my 1998 definitely has the improved wire that does not self destruct like the earlier models. Only thing that is an issue is the coolant temperature sensor plug cracked when I tried to unplug it. Looks like that is replaceable without having to replace the entire harness as there is a part number for the plug head.

On a whim I grabbed the old sensor and put my meter across it. Well what do you know it was reading 1.1 k ohms. I used a couple alligator clips and tied onto pins 12 and 13 on X22 with my meter and plugged the old sensor into the connector on the harness and it read properly. My son and I bent and shook that harness every which way and never got one bit of discontinuity.

So we put the harness back on the car and put the old sensor back in. I measured 1.1k at the connector harness X22:12 and 13, and then plugged it back in the computer box.

Got out my Star computer and hooked it up and started the engine. RPMs were reading 628 to 632, the car was running smooth as a Rolex watch. No codes other than P0100 mass airflow error since I was running with no intake manifold.

Shut down, quickly put the other sensor back in, started back up, could already tell it was running crappy again before I could even get to the RPM display in HHT Emulator. RPMs running between 550 and 750 again. It was throwing P0300 (misfire) and P1315 (CKP) codes again.

Shut down again, swapped in old sensor, started back up, back to normal running and 628-632 rpm. Ran the RPMs up and down with the actuation functions, the engine behaved perfectly and never threw any codes.

Buttoned up the harness properly and put the manifold back on, started back up, the car is running error free.

I got the sensor from Pelican, I will be contacting them in the morning to see about getting a replacement.

Also got to order a new fuel valve and noticed it’s time for injector line clips, several have broken, and need that sensor plug head.

When you looked at the wave form, was the voltage of all sensors tested the same? If the sensor isn't close enough to the ring, voltage will be low.

This is a sensor that slides into a hole in the block and has one retaining bolt correct?

Measure the distance from center of crank sensor to the mounting point on both sensors.

If the sensor is slightly too short due to a manufacturing issue, output voltage will be low / erratic. Check for casting flash on the sensor / something ( rust ) on the engine that would keep the sensor from fully seating.

While yours is probably non adjustable, some sensors ( Chrysler / Jeep ) have adjustable depth and use a thin sticker on the sensors tip to set depth. This spacer gets rubbed off at the first rotation. Granted the Chrysler unit is a hall effect and not an AC generating coil.

ABS sensors are generally an AC generating coil that can be affected by rust pulling the sensor slightly out if it's bore causing ABS to engage at low speed. Sensor depth is that critical.

The scope I picked up was one of the cheap Chinese ones that is the size of a deck of cards. It has a tiny LCD that is good for qualitative analysis and not so much quantitative. My friend came over and we were able to compare side by side but I did not pay attention closely enough to the voltage, I was more focused on the appearance of the waveform and the relative amplitudes. I think this scope can store data but I haven’t figured it out yet, I feel like Sandra Bullock in Gravity trying to figure out how to launch the Chinese escape pod.

Give me an old school Tek 24xx series scope like the old days. I almost bought one second hand but was afraid that it would get destroyed in shipment based on past eBay experiences. I was totally shocked when I opened the box with that Chinese scope, I was expecting something about the size of a small paperback book...

This is a sensor that goes into a bore hole and has a side flange for securing to the block. When I first ran into this issue a few weeks ago I checked the relative length of the sensors and cleanliness of the bore and all was good. I also looked to make sure the surface that seats on the block was clean. And that the sensor had no mold marks or anything else that would interfere.

This is a straight inductive sensor. It is not a Hall sensor; that started with the CDI engines, my OM642s all have Hall sensors. I think either we have a manufacturing defect (they are now made in Romania, so the production line has moved in the last 20 years) or else that difference in the last digit of the part number is significant.