Hello everyone,

I made the famous Arthur Dalton code reader last night and gave it a try on my 1990 300ce M104 24 valve (124.051)

I found a copy of a large PDF file that supposedly has the code tables for my car (apparently it accompanies the "CS1000" fault code scanner). The frustrating thing is that this document does not list the function of many of the active pins in my 16-pin diagnostics unit.

The built-in code reader gives me code 17, which is "02 sensor shorted to positive or ground". I get 4 different codes on Pin 6, which is SRS according to the above-referenced document. I get 7 different codes from pin 14.

When I look at the tables, my car does not show anything for pin 14. On page 28, it shows a number of w124 models in my year range, but it doesn't list 124.051. It's for the Continuous Fuel Injection system.

Socket 14 for the 1992 and up w124's is for the Cruise Control/Idle Control w/o ASR.

The codes on pin 14 that I pulled are as follows, assuming that I should use the table on page 28.

Code 2: Fuel Pump Relay not Functioning
Code 3: TN/TD Signal (RPM) Interrupted
Code 4: Output for o2 sensor heater control defective
Code 5: output for air injection pump control defective
code 6: output for kickdown switch control defective
Code 12: output for A/C compressor control defective
Code 13: excessive A/C compressor clutch slippage

These codes actually do make SOME sense. I had a mechanic pull the same code 2 about a year ago. Although I replaced the MAS Control unit, which should've resolved that.

Code 3 is jargon to me. What does "TN/TD" mean?

I'm not sure what code 5 means, either.

Thanks for your help.