My check engine light came on three days ago and the multifunction display said to check engine electronics. The car ran the same as before the light came on. I started the car yesterday, and when I went to put the car in reverse to back up, a brief message flashed on multidisplay that XXS Disabled and the car shut off. I am not positive what the XX was before the S as it flashed so quickly, I thought maybe ERS, but it may have been CPS. I can not get the message to come back up, and now the car just cranks over but will not start.

From what I read so far, it could be the crank sensor or fuel pump. I am leaning towards crank sensor, but wanted to see what advice may be out there. I would like to test the crank sensor, but not sure of how to do it. Would it measure any Ohms, produce voltage, etc if I put a meter on it? Also, would it put a message on the multidisplay if it went bad?

Thanks for any help.

Have you tried a different KEY?

Possibly a DAS (drivers authorization system) issue?

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MERCEDES Benz Master Guild Technician (6 TIMES)
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190E 2.3 16V ITS SCCA race car (sold)
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I did try that - the key I used when it happened was a key fob with a dying/dead battery - I thought maybe the XXS was a security feature disabling the car. I tried my other working Fob with a good battery and still no start. I tried locking and unlocking the car, as well as disconnecting the battery.

My owners manual says it should work - but my valet key has never started the car (will just turn it over like the current situation I am in) so I have always assumed there to be a sensor in the fob that talks to the security system.

Are the red/green lights in the mirror flashing while you crank?

IF so that IS a DAS issue, IF not checking for fuel pressure OR spark would be the next test.

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MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Does the fuel pump run independent of the crank position sensor? I thought I read in a post that fuel pump will not run if CPS is bad?

The fuel pump only works WHEN the fuel computer (ME) sees a RPM signal from the CPS.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

I checked the green and red lights by the mirror when I went home for lunch - they do not blink when I crank the engine.

I would like to check the crank position sensor and it's cable - can someone tell me where it terminates? I am guessing either the fuse box on the drivers side inner fender, or the computer box on the passenger side fender. I believe the cable is coax, but if someone could conform that as well, I would appreciate it. I should see OHms and voltage on it when the car turns over, right?

Thanks

Dave

CPS is on top of trans bell housing on left side of engine. Look down between rear of engine and firewall.

__________________
Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

Thanks - I will check that tonight.

Another question I have - could a bad Mass Air Flow sensor cause my problem? I should have mentioned this before - when my check engine light came on three days ago (and the last time I drove the car before this problem), I checked the wires under the hood when I got home and I unplugged/replugged in the Mass Air Flow sensor.

OK, I took a look at the car some more when I got home from work. I have no fuel pressure at the rail - I figured I would stop here and check to see if that points to crank sensor before removing top cover of engine to check spark.

Yes, CPS is a strong possibility.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

I traced what I believe to be the cps wire back to the cpu box. I believe it is a green wire and is paired with a purple starter wire (When I disconnected the two, I got no starter, and the two are harnessed together). When the car cranks, I have 5 volts or so on the green wire. Ohms show to be 140 or so. Do these numbers check out? If so, what is my next step - fuel pump relay?

Thanks

Dave

See post #4. 2000 W210 wagon - cranks, but no start when hot

__________________
Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)