crankshaft position sensor for 91 560SEL

[emmydotnet]

I am trying to diagnose a hard start when warm and intermittent rough idle. I suspect it is the crank position sensor. Upon inspection, I found that the cable of the sensor installed appears to be like a 0021533428 because it has the metal bracket that is used to mount the cable onto the left side of the head. Browsing for the crank sensor for a 560SEL, P/N 0021534628 is showing up and basing on the pictures, it does not look like there is a metal mounting bracket. Can someone confirm what is the correct part number for a 91 560SEL? Do I have the wrong sensor installed based on the sensor having the metal mounting bracket?

Thank you

[porkface]

002 153 35-not 34-28 is replaced by 000 153 88 20, both nla. never found 002 153 34 28.

002 153 46 28 is at the front of the engine and is for the 10 pin connector for the factory test tool. has nothing to do with the way the engine runs. sounds like more testing is needed before trying to find the white elephant crank sensor. good luck, chuck.

[emmydotnet]

Thank you for the clarification. The sensor I am referring to is the one connected to the EZL and to the rear of engine drivers side. I thought this is referred to as the crank position sensor that is input to ignition timing?

[RPM55]

The sensor you are referring to is the crank position sensor but it is unlikely the cause of your problem. Those parts rarely fail ( at least on this engine series ).

I think some more thorough diagnosis is needed.

[porkface]

you are right as is rpm55-they rarely fail. replaced a couple over the years but the 103/104 and 112/113 engines way more often.

i cobbled together a test harness from the abs connectors from a 123, but that vintage, all abs connectors are the same. get the male and female, splice them together with extra terminals to attach scope leads. use lotsa wire to make it easy. plug both ends to the ezl and sender harness and watch the signal. a scope is better because you can see the signal, numbers on a dvom won't help. good luck, chuck.

[emmydotnet]

Pork face, are you suggesting measuring the signal from the sensor into the EZL? So the resistance readings of the sensor at various Temps will not suffice for analysis?

[EricSilver]

Does your car have a camshaft position sensor?

That could be the problem if it does.

[emmydotnet]

Eric Silver- not sure what you are implying. Yes my car has the camshaft sensor in the front of the engine. But this sensor does not feed into the EZL so it should not have anything to do with ignition.

[EricSilver]

I had the same issue on my E430. Assumed it was crank sensor -- but code reader said cam sensor, and was correct.

On your car it is the "Top Dead Center" sensor and connects to the ECU. If it is failing then the "car can have a multitude of problems, from rough running all the way to not starting at all." Sounds like what you are experiencing. Here is the local opinion:

PeachParts: Replacing Your Mercedes-Benz Top Dead Center Sensor
https://www.pelicanparts.com/techarticles/Mercedes-W126/10-ELEC-Tackling_The_Top_Dead_Center_Sensor/10-ELEC-Tackling_The_Top_Dead_Center_Sensor.htm

Note the comments at the end in bold.

Originally Posted by emmydotnet

Eric Silver- not sure what you are implying. Yes my car has the camshaft sensor in the front of the engine. But this sensor does not feed into the EZL so it should not have anything to do with ignition.

[emmydotnet]

Originally Posted by EricSilver

I had the same issue on my E430. Assumed it was crank sensor -- but code reader said cam sensor, and was correct.

On your car it is the "Top Dead Center" sensor and connects to the ECU. If it is failing then the "car can have a multitude of problems, from rough running all the way to not starting at all." Sounds like what you are experiencing. Here is the local opinion:

PeachParts: Replacing Your Mercedes-Benz Top Dead Center Sensor
https://www.pelicanparts.com/techarticles/Mercedes-W126/10-ELEC-Tackling_The_Top_Dead_Center_Sensor/10-ELEC-Tackling_The_Top_Dead_Center_Sensor.htm

Note the comments at the end in bold.

reading that article by pelican parts, if you read the 4th comment by Jack dated November 3, 2016, it supports what I am talking about. Therefore, it is not the cam sensor that you are referring to but rather the CPS at the back of the engine left side by the transmission. Thanks for the insight anyways

[EricSilver]

I know, and if you read the Pelican Parts response to Jack, which is also reiterated in the Bold text at the end of the article, it says that the sensor shown in the pictures is not the one that needs to be replaced or which connects to the ECU, but there is another one on the transmission side they said which does.

Why they didn't bother to includea picture of the actual sensor in the tutorial is a mystery, adds much confusion.

[EricSilver]

( unless the "cylinder ID sensor" the tutorial refers to is also the crank sensor. As I said it's confusing and even misleading..)

[Frank Reiner]

Originally Posted by emmydotnet

Pork face, are you suggesting measuring the signal from the sensor into the EZL? So the resistance readings of the sensor at various Temps will not suffice for analysis?

Temperature is not a consideration in diagnosis of the crankshaft position sensor (CPS). The temp vs. resistance readings are for the water temperature sensor.
The spliced-in test connection detailed by porkface is a useful tool for observing the output of the CPS; it allows the generated electrical pulse to be observed in real-time.

Originally Posted by emmydotnet

Eric Silver- not sure what you are implying. Yes my car has the camshaft sensor in the front of the engine. But this sensor does not feed into the EZL so it should not have anything to do with ignition.

The M116/117 engines do not have a camshaft sensor.
Unfortunately the "information" in the PeachParts link is erroneous, and should be ignored; the magnetic pickup at the front of the engine is NOT connected to either the ECU or the EZL.

[porkface]

in my experience, crank sensors fail outright and i haven't SEEN stumbling and/or hard starts. possible, yes but not likely. usually it's running ok until the sensor heats up and the car stalls. cools off, starts fine.

in those cases, and yours, i hook my test lead up to my scope, close the hood to keep the heat in and watch while cranking or it's running. once it stalls, crank again and watch. testing for resistance won't work because you don't know the temp it fails at-if that's the case. and any voltage can pass through during an ohms test, but is it enough?

in your case, without testing anything, i would look at the ignition system. new and correct plugs-bosch or ngk copper only-no platinum. bosch oe style cap and rotor-no other brands. plug wires-not bosch gray silicone but beru or karlyn are fine. look at the coil, see any white-out on the outside? flashover burns from a failing coil-very common in that generation ignition setup due to too much resistance in the other ignition parts. all ok looking-then i test. scope the coil and look at the secondary kv. then scope the crank sensor.

leaking injectors and/or fuel distributor can also cause the same symptoms. but then, i can't see under your hood. the light here sucks. good luck, chuck.