1988-2000 Mercedes-Benz Fault Code Manual

Fault Code Manual for Mercedes-Benz Analog Systems 1988-1997 Digital Systems 1993-2000 ©Baum Tools Unlimited Inc. February 1, 2001

2 Table of Contents The Diagnostic Process Information Gathering .................................................................... 4 Diagnostic Codes & Adaptation Diagnostic Code Readout ................................................................. 6 About Stored, Registered and Current Faults ................................................... 6 Fault Code Types ....................................................................... 7 Check Engine Light (MIL) Diagnosis ......................................................... 7 Mixture Adaptation ....................................................................... 8 Resetting and Reactivating BOSCH Engine Control Module Memory ................................. 9 Using the Data Stream .................................................................... 9 Equipment Connections Connection Table ....................................................................... 10 Connector Layout of Vehicle Diagnostic Connector ............................................. 11 8-pole Diagnostic Connector ......................................................... 11 16-pole Diagnostic Connector ......................................................... 11 38-pin Diagnostic Connector ......................................................... 12 9-pole Diagnostic Connector (1980-94) ................................................. 13 Mercedes Model Identifier ............................................................... 100 Fault Codes Engine Control Electronic Diesel Idle Speed Control (ELR) .................................................... 14 Electronic Diesel System (EDS) ............................................................. 14 Continuous Fuel Injection System (CFI) ....................................................... 15 Continuous Fuel Injection System (MAS Controller) .............................................. 16 LH Sequential Multiport Fuel Injection System - Analog .......................................... 17 LH Sequential Multiport Fuel Injection System - Digital ........................................... 18 HFM Sequential Multiport Fuel Injection System - Analog ......................................... 20 HFM Sequential Multiport Fuel Injection System - Digital .......................................... 22 PMS (PEC) Fuel Injection System .......................................................... 25 ME Sequential Multiport Fuel Injection System ................................................. 26 Diagnostic Module (DM) - Analog ........................................................... 41 Diagnostic Module (DM) - Digital LH (104, 119, 120) ............................................. 43 Diagnostic Module (DM) - Digital HFM (104, 111) ............................................... 45 Base Module (BM) - LH-SFI ............................................................... 47 Distributor Ignition (DI) - LH-SFI ............................................................ 48 Cruise Control/idle Speed Control (CC/ISC) w/o ASR ............................................ 49 Electronic Accelerator / Cruise Control / Idle Speed Control (EA/CC/ISC) w/ASR ....................... 50 Chassis Control Electronic Automatic Transmission Control (ETC) CFI (722.5) ...................................... 51 Electronic Automatic Transmission Control (ETC) 1990-95 (722.5) .................................. 51 Automatic-engaged Four-wheel Drive (4MATIC) ................................................ 52 Electronic Automatic Transmission Control (ETC) 1996-2000 (722.6) ................................ 53 Adaptive Damping System (ADS) ........................................................... 54 Automatic Locking Differential (ASD) ......................................................... 55 Anti-lock Brake System (ABS) .............................................................. 55 Anti-lock Brake system (ABS w/ASR) ........................................................ 56 Electronic Traction Systems (ASR, ETS) ...................................................... 57 Speed Sensitive Power Steering (SPS) ....................................................... 58

3 Electronic Traction Systems (ABS, ASR, ETS, SPS) Digital ....................................... 59 Body Control Cabriolet Soft Top (CST) ................................................................. 61 Roll Bar (RB) for CST .................................................................... 61 Roadster Soft Top (RST) ................................................................ 62, 63 Roll Bar (RB) for RST .................................................................... 63 Infrared Remote Control For Central Locking (IRCL) ........................................... 64, 65 Pneumatic Systems Equipment (PSE) ........................................................ 65 Anti-theft Alarm System( ATA) .............................................................. 66 Cellular Telephone (CT) ................................................................... 66 Convenience Features (CF) ................................................................ 67 Supplemental Restraint System (SRS) ....................................................... 68 Supplemental Restraint System (SRS) BAE, ZAE System ......................................... 68 Supplemental Restraint System (SRS) with Side Airbags .......................................... 69 Body Control Systems (SRS, IRCL, PSE, ATA. RST, MSC, CF) Digital ............................... 70 Climate Control Tempmatic A/C ......................................................................... 73 Automatic A/C .......................................................................... 74 A/C SELF DIAGNOSTIC SYSTEMS TAU 2.1 ........................................................................... 75 129 Chassis 1990-95 ................................................................. 77 129 Chassis 1996-99 ................................................................. 79 140 Chassis 1992-95 ................................................................. 81 140 Chassis 1996-99 ................................................................. 86 202 Chassis 1995 ................................................................... 89 202 Chassis 1996-99 ................................................................. 93 210 Chassis 1996-99 ................................................................. 94 Mercedes Technical Acronyms ........................................................... 97 Mercedes Model Identifier ............................................................... 100 Mercedes Diagnostic Manuals .......................................................... 106 Technical Support Contact Information ................................................. 107 DISCLAIMER: All information contained in this document is correct to the best of our knowledge. Errors may occur therefore Baum Tools Unlimited Inc. makes no warrantee, guarantee or assurance that damage may not occur from the use of this information. The user takes all responsibility for its use. Mercedes Benz is a registered trademark of Daimler Chrysler AG. Copyright © 1998-2001 BAUM TOOLS UNLIMITED INC. All rights reserved. Any reproduction in whole or in part without permission is strictly prohibited.

4 This book is designed to help you in the basic diagnostic procedures for Mercedes Benz. It is intended to be a starting point in the diagnostic process and is not intended to be a complete resource. THE DIAGNOSTIC PROCESS The diagnostic process divides itself into several levels; Information Gathering, Analysis of Codes, Testing and then Repair. We will cover Information Gathering and Analysis of codes in this book. For those experienced in diagnostics jump to page INFORMATION GATHERING The information gathering stage always starts with the Customer. Step 1 The Customer Interview This is truly an art. It consists of getting the Customer to tell you what the complaint is and under what conditions it occurs. The customer of course is, as always, the “MOST HELPFUL” source of information. Their concise insight into the problem is a valuable step in getting the problem solved and the car back on the road. Also it’s the most fun part of the diagnostic process. Watching the customer use body gestures, make funny faces and funny sounds in an attempt to imitate vehicle noises can really brighten your day. Actually the process of getting the information out of the customer can be relatively painless if you ask the correct questions. Here are some suggestions: 1) What is the problem/symptom(s)? 2) When did it start? 3) Under what conditions did the problem/symptom occur (if intermittent)? Wet, dry, hot, cold or changing weather, rough road,...etc. 4) Has there been any work done on the car recently? New radio, shocks, tires...etc? 5) Any jump starts or hard starts with long crank times. 6) Did you run out of gas recently? 7) Are you sure this hasn’t happened before, even for a short time? Next the exact nature of the complaint must be addressed. Step 2 The Test Drive Go on a test drive with the Customer so you can/cannot experience the problem/symptom. This ensures that the malfunction you try to diagnose and fix is the one with that the customer is concerned about and that it is a real malfunction and not just a lack of understanding of normal vehicle operation. Few things are more frustrating for you and the customer than repairing a suspension noise in the front of the car (even if it did need new shocks, thrust bushings, brakes and a set of tires) when it was an engine noise that the customer wanted fixed. It is also a good idea to let the customer drive on the outbound leg so you can watch the customers driving technique. The customer is more likely to be able to make the car “do it” then you will. Sometimes a customer can mistake normal vehicle operation for a problem. An example of this is a customer whose vehicle has an Anti-Lock Brake System (ABS), and is concerned because of a pulsating brake pedal when braking hard. Since many people are unaware of this characteristic of normal ABS operation, they mistake this for a malfunction. Also if you start diagnosing a vehicle for a problem when the vehicle is operating normally, you can be in for a long frustrating day.

5 Step 3 Visually Inspect the Vehicle Don’t leave out this step. You can save lots of time with this. Engine - Look under the hood. Check for missing covers, oil and water splash, burn marks, nesting materials, mis-routed wiring and anything else that looks out of place. ABS/ASC/DSC/ASR - Lift hood and inspect the fluid level. Raise the car and inspect the brakes/wheels for excess dust and corrosion. Check that all static charge grounding straps are in place. Transmission - Look for beverage spillage on the center console area. Look for problems in the operation of the instrument cluster and on-board computer. These systems share data with the engine, transmission and traction systems. Inspect the transmission housing and connection cables. SRS/Airbag - Has the car been in a collision, jumped a curb, been to the body shop (welded) or jump started. Any or all of these can be signs of something amiss. Remember you’re gathering information at this point so don;’t ignore anything at this step. Step 4 Check the Battery Visually inspect the battery for corroded cables and terminals. Also old batteries are pure trouble in a late model car. If you see any problem clean it up and grab your DMM (Fluke 88, Vantage, or whatever volt meter you use) and ... Check voltage Key Off Engine Off, KOEO and KOER. Key Off Engine Off >11.4Volts KOEO >11.4Volts KOER >13.2 but not higher than 14.2volts Step 5 Recall Fault Codes Even without a “Check this or that Light” illuminated, pull the codes from all systems, not just the suspect system. Late model cars have highly integrated controls and faults can cascade from one system to another. Simple things like and wrong size tire can turn on the Transmission Failure message, yet not turn on the ABS or ASR light. Both systems, though, may register codes. Record and then Clear the codes. Write them down. Write them down. Write them down. There is nothing more fun then the call to tech support that starts. Technician: “I got this code. Something about the O2 sensor. I replaced it but the code came back the next day. Why?” Tech Support: “What is the type and year of the car and what was the fault code number?” Technician: “It was a ‘94 C220, but I don’t remember the code number. It came in last week.” Tech Support: (Knocking back another bottle of Mallox) “Could it have been a Lambda Control code?” Technician: “Ya! I think that was it. Why’d the new plugs make it go away and not the new O2 sensor?” Test drive the car then pull the codes again. For some codes you will need to perform 2 test drives to get a code.

6 Diagnostic Codes & Adaptation Diagnostic Trouble Code (DTC) Readout: The engine control module (N3/4) for the LH-SFI, HFM-SFI and ME-SFI systems are equipped with diagnostic trouble code (DTC) memory. Malfunctions are recognized and stored as trouble codes and are distinguished as follows: u Malfunctions which are constantly present, u Malfunctions which occur longer than a pre determined number of seconds, u Intermittent contact malfunctions which have occurred 5x during a trip. The DTC memory remains active even if the vehicle's battery is disconnected. Malfunctions which are no longer present, are automatically erased again after a maximum of 19 trips. Under HFM-SFI a TRIP has occurred if: u Engine running more than 5 minutes u Vehicle speed >4 km/h (2.5 mph), u Engine speed >700 rpm, u Engine shut off for 30 seconds. Under ME-SFI a TRIP is u Engine running for more than 20 minutes, u Engine temperature is greater than -7 degrees C, u Engine speed is greater than 500 RPM, The stored diagnostic trouble codes (DTCs) can be read at the 16 (124 E-class) or 38 pin data link connector (X11/4) with the ignition switched "ON" or with the "engine running". Diagnosis via an on-off ratio readout has been eliminated in all models. About Stored, Registered and Current Faults Stored or Permanent Faults - These faults generally turn on the MIL (malfunction indicator lamp previously known as the Check Engine Light) and are recorded in the permanent memory of the cars system controller. Clearing these codes most often will extinguish the MIL. (See Registered Faults below.) Registered or Pending Faults - These faults can keep the MIL on. These faults are recorded in the temporary memory of the of the cars system controller. This temporary memory records the number of times a component fails. When a certain number of failures has occurred the fault is moved to permanent storage and the Check Engine Light (MIL) will be illuminated. On cars equipped with Fault Registers the Check Engine Light may stay on after the Stored or Permanent Fault has been erased if another occurrence of the fault has happened since the original Permanent Fault was stored. To ensure the MIL is extinguished, erase the Stored and Registered faults. Current or Actual Faults - These faults are detected while the car is running at idle or speed. They represent components currently failing or, in the case of HFM and LH systems, components not present. These codes cannot be erased, and are only meaningful with the ignition on and the engine running. Codes found in this system with the KOEO have no meaning. Components not present on the vehicle may be flagged as failing by the cars internal diagnostics due to the generic nature of the cars software. This is particularly true in C-Class (202) cars.

7 Fault Code Types There are basically 2 code types. Component failure codes and System Malfunction or Logic codes. Component Failure Codes are just that. The ECU specifically targets a “component” as failing. These codes make it easy to spot the problem. Some of these components are: Oxygen Sensor MAP MAF TPS Vehicle Speed Sensor Coolant Temperature Sensor Intake Air Temperature Sensor Camshaft Position Sensor Crankshaft Position Sensor Exhaust Temperature Sensor Injectors Ignition (coils) Idle Air Valve Pressure Regulator (optional) EGR Valve EVAP Purge Valve Secondary Air Valve Secondary Air Pump...etc. System Failure or Logic Codes indicate that, when the “system” operated it did not produce the desire result. Examples of these codes are; Fuel Trim, O2 Control at Limit (Lambda control) Possible cause: Fuel tank ran empty, Incorrect Fuel Pressure, Injector valve defective or coked, Engine Temperature Sensor defective, EGR valve leak, Secondary air leak, EVAP control system defective, Air Mass Meter defective, O2 sensor aging (slow response) or inactive, Combustion disturbed by mechanical failure (Spark plugs, compression, intake/exhaust valves, ...etc.) Ignition Feedback Fault Possible cause: Coils, Sparkplug Wires, Sparkplugs, ECU, Low or high battery voltage. ASR CAN Signal to Another Controller Lost. Possible cause: ABS/ASR Control Unit Fault, ABS/ASR Component Fault, CAN Bus Communications Fault, Faulty Electronic Accelerator (EA) controller, Faulty EA Actuator, Low or high battery voltage. Electronic Accelerator Fuel Cutoff Signal to Engine Control Possible cause: Faulty EA Actuator System, Faulty EA Actuator, Low or high battery voltage ECU Faults Internal Control Module, internal communication fault Internal Control Module, Keep Alive Memory (CMOS) Internal Control Module, Memory check sum (ROM/RAM) Internal Control Module, RAM Internal Control Module, EEPROM. Load Calculation Cross Check, Range/Perf....etc. These types of codes are more difficult to diagnose, but generally there will be other conditions that can give you a clue. Other fault codes will be present, physical engine condition (wear and tear), nature of the complaint itself, and information from the datastream can help refine your analysis.

8 Check Engine Light (MIL) Diagnosis Mercedes S(140), SL(129), E(124, 210) and C(202) class have multiple systems which can turn on an Check Engine Light. All related systems must be tested for codes and repaired before the light will extinguish. Injection System Diagnostic Socket Pin and CS1000 System to Use 129 LH (1992-95) LH (pin 4 & 5), EA/CC/ISC (pin 7), BM (pin 8), DI (pin 17 & 18) and DM (pin 19 check stored and registered codes only) 140 LH (1992-95) LH (pin 4), EA/CC/ISC (pin 7), BM (pin 8), DI (pin 17) and DM (pin 19 check stored and registered codes only) 124 HFM (1993-95) HFM (pin 8), EA/CC/ISC (pin 14), and DM (pin 3 check stored and registered codes only) 140 HFM (1993-96) HFM (pin 4), EA/CC/ISC (pin 7) and DM (pin 19 check stored and registered codes only) 202 HFM (1995-96) HFM (pin 4), EA/CC/ISC (pin 7) (except C220) and DM (pin 19 check stored and registered codes only) 210 HFM (1996-97) HFM (pin 4), EA/CC/ISC (pin 7) and DM (pin 19 check stored and registered codes only) Note: ME-SFI injected vehicles integrate Injection, Ignition, Electronic Accelerator, Diagnostic Module and Base module into the ME controller module. Mixture Adaptation: The Lambda control system precisely determines fuel injection duration so that the fuel/air ratio is consistently kept at Lambda equal 1 (Lambda=1 is 14.7 kg air per 1 kg fuel) under all operating conditions. Should a malfunction occur in the form of: u Intake air leaks u Injector defects or carbon build-up, u Air Flow Sensor defects u Pressure regulator defects, such as a blown diaphragm. u Fuel tank purge control valve defects or EVAP system leaks.] u EGR defects u Vacuum leaks of any kind. u Mechanical engine wear, such as, chipped valves or leaking rings. The engine control module automatically performs a mixture adjustment. The degree of correction is calculated constantly and stored in KAM (Keep Alive Memory) RAM. The self-adaptation is performed at idle and under partial load. Maximum correction towards rich or lean is 25%. After repair work is performed, the engine control module will automatically adapt itself again after approx. 10 trips. After eliminating a malfunction or after trial installation of an engine control module from another vehicle, the self-adaptation feature must be reset to its mean value.

9 "Resetting and Reactivating for BOSCH Engine Control Module Memory" For LH & HFM systems only. To reset and reactivate the module : 1. Read and clear all fault codes 2. After display of 1 (No faults present) short the diagnostic plug (pin 8 for 16 pin diagnostic socket, pin 4 for 38 pin diagnostic socket) to ground for 6 to 8 seconds 3. Switch ignition off and wait at least 5 seconds 4. Turn ignition on, wait minimum of 10 seconds then restart engine. Long Term Adaptation (Additive) - Engine at idle. Short Term Adaptation (Multiplicative) - Engine at partial load The correction towards rich or lean is + - 1.0 msec (Injection Duration) at idle and the factor of 0.68-1.32 at partial load. After repair work is performed the engine control will automatically adapt itself again (ME injection) over the course of 10 TRIPS. Codes Present in the Absent of Trouble Light Not all control systems will trigger codes or turn on malfunction lights when codes are stored. INJECTION/IGNITION system problems will trigger trouble codes, but may not turn on the MIL unless the fault results in a change in the exhaust gases or can damage the engine in the short term. Also some mechanical problems in earlier cars (pre 1988-96) can cause poor drivability without ever tripping a code or turning on the light. On later models that is much less likely. BRAKING/TRACTION systems will only turn on their check light when the system has become inactive. It does not mean there isn’t a problem and codes haven’t been stored. TRANSMISSION systems will turn on the “Check Engine” light if any shared system is detected as failing test. AIRBAG and RESTRAINT SYSTEMS will turn on the light and record codes if incorrectly coded for the car. A good example is the 1995 C280 and the 1995 S320. The same controller is used in both vehicles, however the S-class has more features in the Airbag system such as side bags and baby seat detection. The coding of the controller for the C280 masks the features not present so the controller doesn’t register a code. The controllers generally come off the parts dept. shelf coded for maximum features. In All Systems low or high battery voltages can trigger invalid or multiple codes without real failures of the indicated components. Always check the battery condition before starting analysis. Using the Data Stream to Diagnose/Confirm Faults The Serial Data Information Stream of the ECU is a “window” into the operation of the system under test. By looking at the values of the suspect components in operation and the computed values of the ECU, we can build a picture of the operation of the system and what is causing the fault. The interpretation of the Data Stream is beyond the scope of this book. Please refer to the Diagnostic Manuals from Mercedes Benz for complete discussion of the topic. The nominal values for all Mercedes vehicles 1990-2000 can be found in the Mercedes Engine Diagnostic Manual Volume 1 Section A. A listing of these manuals can be found at the end of this document. Multiple system and component faults can almost always be traced to faulty wiring harnesses or water damage.

10 Connection Table Test Lead of Cable Connection source Red Power -To power supply socket or vehicle battery Black Ground - To socket 1 Yellow To diagnostic test socket Power supply (B+) socket on the vehicle Diagnostic Connectors 8-pole connector Use with the battery extension cable to the vehicle battery 16-pole connector Socket 16 (circuit 15 - ignition ON)* Not present in some models. Use battery +. 38-pole connector Socket 3 (circuit 30 - Battery+) *Must be performed with the ignition ON to power up the scanner Ground (-) socket on the vehicle Diagnostic Connectors 8-pole connector socket 1 16-pole connector socket 1 38-pole connector socket 1

1988-2000 Mercedes-Benz Fault Code Manual

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