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  #1  
Old 11-13-2010, 11:19 AM
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Reading & Clearing Diagnostic codes

Hello All,

Back to my 300CE-24 type W124.051.

Bosch KE injection with EZL, 5-speed 722.5 box etc. etc.

Started reading some codes today.

Please bear in mind that I've already used my home made box to read and clear a gearbox fault that prevented 4th gear remaining engaged and generally made the car miserable to drive. All that's now OK and the car's really going well aside from an intermittent reverse issue that I've addressed separately.

I have the 16-pin diagnostic socket near the battery.

1. Connected reader to battery.

2. Connected probe to pin 3 - CFI System

3. Read code 13: Intake air temperature is illogical.

>>> That's fine. It's entirely consistent with my last, dramatic improvement; that of replacing the dead sensor.

4. Attempted, several times to erase this code.

>>> I cannot erase this code!!!

5. Connected probe to pin 8 - Distributor ignition.

6. Read code 11: Preference resistor faulty.

>>> Don't understand this. I wonder what it is?

7. Read code 17: Crankshaft position sensor faulty.

>>> That's consistent with previous problems that the new CPS improved significantly.

>>> I cannot erase these codes (11 and 17). It has a new temperature sensor and a new CPS.

All this is interesting but not a major problem as I'm really very pleased with the way the car's going. I had a brilliant run yesterday in a mixture of heavy rain and sun and it was really enjoyable.

Does anyone have any thoughts?

The best to all.

RayH

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  #2  
Old 11-15-2010, 08:35 AM
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To read codes from the ignition module the engine must be running.
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  #3  
Old 11-15-2010, 11:19 AM
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Oh!

Quote:
Originally Posted by M.B.DOC View Post
To read codes from the ignition module the engine must be running.
Thank you for that. Does that apply to deleting them too?

Do you have any idea why I'm unable to delete codes from the CSI?

Thanks again.

RayH
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  #4  
Old 11-15-2010, 12:05 PM
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Unless the sensor circuit is open/ shorted the code should clear.

Is that a California car? have a pushbutton & red LED on the diagnostic connector?
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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)
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  #5  
Old 11-15-2010, 01:15 PM
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'94 S500: only 793 sold!
 
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Location: San Diego, CA
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Quote:
Originally Posted by rayhennig View Post
Hello All,
Back to my 300CE-24 type W124.051.
Bosch KE injection with EZL, 5-speed 722.5 box etc. etc.

Started reading some codes today. I have the 16-pin diagnostic socket near the battery.

1. Connected reader to battery.
5. Connected probe to pin 8 - Distributor ignition.
6. Read code 11: Reference resistor faulty.

>>> Don't understand this. I wonder what it is?
Check Menu#5 ( http://www.k6jrf.com/MB_DI.html ) for details. RR is shown as "2". Maybe it's missing?? or damaged?

Quote:
Originally Posted by rayhennig View Post
Hello All,
7. Read code 17: Crankshaft position sensor faulty.
>>> I cannot erase these codes (11 and 17). It has a new temperature sensor and a new CPS.

Does anyone have any thoughts?
RayH
About 1 year after purchasing my '94 S500 cpe, I got the same error code and the CE light. Turns out that a "memory-bit" inside the DI Module went bad so the CE light would come one instantly and the code couldn't be erased. Otherwise the car ran fine. Finally had to replace the DI Module.

Looks like you have the same problem.

Probably you have a good CPS . . .they never go bad on the early MBs b/c the ckt consists of a magnet and some wire! Hard for the "ckt" to fail! An ohmmeter should show about 1200 +/- 200 ohms.
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  #6  
Old 11-16-2010, 01:32 AM
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Thanks to all ...

Thank you, sir.

One point. I think your vehicle is later than mine and does not have the KE Jetronic injection with separate electronic ignition that my 1991 car has.

Having said that, you suggest that the 'reference resistor' is that which is plugged into the ignition control module and, presumably, retards the ignition. If so, that makes sense to me as I have removed that resistor over the years in order to test the vehicle's performance and fuel consumption when using 98 (as opposed to 95) RON fuel. Never noticed any significant improvement.

So, the system might have logged the removal of the resistor as a fault.

I still cannot understand why I can't erase the faults. I did so for the auto box and it now works very well.

Oh well, As long as the thing drives well I suppose that's the main thing.

Thanks again.

RayH
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  #7  
Old 11-16-2010, 01:54 AM
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'94 S500: only 793 sold!
 
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Quote:
Originally Posted by rayhennig View Post
I still cannot understand why I can't erase the faults.
One more time . . . the module has an internal failure in the onboard memory. Similar to a computer's memory stick. The failure causes the unit to register a fault that's not really there! It's that simple . . . .
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  #8  
Old 06-13-2011, 09:23 PM
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Posts: 121
Jim,
How did you find and test for the "memory-bit" failure inside the DI Module? Is this the same as the Ignition Control Module?

I have code 6 (Camshaft Position Sensor) which is constantly there along with hard/no start isues with random stalling in town. I leaning towards my ICM.
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  #9  
Old 06-14-2011, 02:43 AM
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'94 S500: only 793 sold!
 
Join Date: Mar 2001
Location: San Diego, CA
Posts: 1,933
Over the years reading stored DTCs from many DI modules, I've found some that have memory failures that indicate a DTC but it's not a real b/c of a bad internal memory bit in the module itself.

It started about 1 year after I got the '94 S500. The DI module suddenly showed the "CKS" sensor as failed. The CKS is a non-electronic device (some wire wrapped around a magnet that measures correctly) so that showed me that a DI module can fail causing the CE ckt to light generating a DTC that is NOT real! Once the CE lamp is on, just try to pass a CA smog test. Real or not, it's counted as real!

After replacing the DI module, a few years later, the module showed a DTC = "Reference Resistor is bad". Well, it's NOT (it's there and measures correctly) but the DI module "thinks" it's bad. The good news is that the REF RES failure does NOT cause the CE lamp to lite b/c it's not an EMISSIONS related failure as was the CKS. This failure has been there for a least 13 years or more.

In your case, I might tend to believe the failure b/c of stalling, hard-starts, etc.

Hope this helps.

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