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Mercedes-Benz 300TE 4Matic 1990 - G - TESTS W/CODES 1990 ENGINE PERFORMANCE Mercedes Benz Self-Diagnostics
Mercedes-Benz 300TE 4Matic 1990 - INTRODUCTION
If no faults were found while performing the test procedures in the BASIC TESTING article, proceed with ENTERING SELF-DIAGNOSTICS in this article. If no fault codes or only pass codes are present, proceed to the TESTS W/O CODES article for diagnosis by symptom (i.e. ROUGH IDLE, NO START, etc.).
NOTE: All voltage tests should be performed with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless specifically stated different in testing procedures.
Mercedes-Benz 300TE 4Matic 1990 - SELF-DIAGNOSTIC SYSTEM HARD FAILURES
Hard failures cause malfunction light to illuminate and remain on until the malfunction is repaired. If light comes on and remains on (light may flash) during vehicle operation, cause of malfunction must be determined using diagnostic (code) charts. If a sensor fails, control unit will use a substitute value in its calculations to continue engine operation. In this condition, vehicle is functional, but loss of good driveability will most likely be encountered.
Mercedes-Benz 300TE 4Matic 1990 - INTERMITTENT FAILURES
Intermittent failures may cause malfunction light to flicker or illuminate and go out after the intermittent fault goes away. The corresponding trouble code, however, will be retained in control unit memory. If related fault does not reoccur within a certain time frame, related trouble code will be erased from control unit memory. Intermittent failures may be caused by sensor, connector or wiring related problems. See INTERMITTENTS in TESTS W/O CODES .
Mercedes-Benz 300TE 4Matic 1990 - ENTERING SELF-DIAGNOSTICS FLASH CODE METHOD (CALIFORNIA)
An on-board test connection with push button and light emitting diodes is located on left, rear engine compartment firewall. See Fig. 1 . To enter self-diagnostics, turn ignition on and press diagnostic connector push button No. 2, for 2-4 seconds. See Fig. 1 and Fig. 2 . Impulse readout will commence flashing code sequence. Codes may also be retrieved through use of an impulse counter.
Mercedes-Benz 300TE 4Matic 1990 - IMPULSE COUNT READOUT
- To retrieve codes, connect Impulse Counter (124 589 19 21 00) to diagnostic connector, or by connect Multimeter and Socket Box Tester (124 589 00 21 00) by test cables to CIS-E control unit or to MAS unit (if equipped). See Fig. 2 . Connect appropriate tester as shown in appropriate illustration. See Fig. 3 -5. On models equipped with V8 engine, use only multimeter, socket box tester and CIS-E control unit diagram.
- Connect impulse counter leads to diagnostic connector pins No. 1 and No. 3. Connect red wire to battery voltage. See Fig. 4 and Fig. 5 . Using multimeter, connect leads to socket box tester pin sockets No. 1 and No. 2. Remove CIS-E control unit connector. Connect socket box tester connectors to CIS-E control unit and to CIS-E control unit harness connector as shown in appropriate illustration. See Fig. 3 -5.
Mercedes-Benz 300TE 4Matic 1990 - RETRIEVING CODES (CALIF VEHICLES)
Enter self-diagnostics. See ENTERING SELF-DIAGNOSTICS . Malfunction code will be indicated by number of blinks emitted from LED. Upon completion of blink impulse readout, LED will remain on (does not blink). Press push button No. 2 again for 2 to 4 seconds. If another malfunction exists, it will be indicated at this time. If no other malfunction is detected, CIS-E control unit switches over to on-off ratio readout.
Mercedes-Benz 300TE 4Matic 1990 - RETRIEVING CODES (FEDERAL VEHICLES)
Enter self-diagnostics. See ENTERING SELF-DIAGNOSTICS . Multimeter will indicate code(s) stored in memory.
Mercedes-Benz 300TE 4Matic 1990 - CODE AND COMPONENT
Mercedes-Benz 300TE 4Matic 1990 MALFUNCTION DIAGNOSTIC CODES
Code/No. of Flashes Malfunctioning Component 1 No System Malfunction 2 Throttle Valve Switch 3 Coolant Temperature Sensor 4 Airflow Sensor Position Indicator 5 Oxygen Sensor 6 Not Used 7 Td Signal 8 Altitude Correction Capsule 9 Electro-Hydraulic Actuator (EHA) 10 Throttle Valve Switch Idle Speed Contact 11 Not Used 12 (1) EGR Temperature Sensor
(1) California 420 and 560 Series only.
Mercedes-Benz 300TE 4Matic 1990 - TESTING WITH ON-OFF RATIO TESTER
NOTE: Perform On-Off Ratio Test and record results. Proceed to appropriate, TEST STEP as indicated in TROUBLE SHOOTING charts. See TEST STEP CHARTS in this article and perform indicated circuit tests to repair vehicle.
Mercedes-Benz 300TE 4Matic 1990 - ON-OFF RATIO TEST
- Connect On-Off Ratio Tester (Bosch KDJE-P 600) to test socket (on left side of engine compartment). See Fig. 4 . Turn ignition on. Perform On-Off Ratio tests. Record results of (0)/0 readout shown on On-Off Ratio Tester. See TROUBLE SHOOTING - IGNITION ON, ENGINE OFF .
Fig. 4: Mercedes-Benz 300TE 4Matic 1990 - Component Locations - On-Off Ratio Tester - Start engine and allow to idle. Perform and record results of percentage readout shown on on-off ratio tester. See TROUBLE SHOOTING - ENGINE IDLING .
- After recording (0)/0 readouts from both tests and note test steps to be performed, refer to appropriate test step and correct malfunction. See TEST STEP CHARTS in this article.
Mercedes-Benz 300TE 4Matic 1990 - TROUBLE SHOOTING TROUBLE SHOOTING - IGNITION ON, ENGINE OFF
Mercedes-Benz 300TE 4Matic 1990 TROUBLE SHOOTING - IGNITION ON, ENGINE OFF
On-Off Ratio % Readout Malfunction Test Step 0 Not Used Not Used 10 Throttle Valve Switch Idle Contact Open 10.0-10.3 20 Throttle Valve Switch Full Load Contact Closed 5.0-5.3 30 Coolant Temperature Not Between 70?-100?C 6.0-6.3 40 Airflow Sensor Plate Deflected 7.0-7.6 50 Input Signals In Order N/A 60 Speed Signal Recognized 11.0-11.2 70 Starter Signal Circuit No. 50 Recognized 20.0 80 Drive Position Selected N/A 90 Current at EHA Unlikely 4.0-4.4 100 Not Used N/A
Mercedes-Benz 300TE 4Matic 1990 - TROUBLE SHOOTING - ENGINE IDLING
Mercedes-Benz 300TE 4Matic 1990 TROUBLE SHOOTING - ENGINE IDLING
On-Off Ratio % Readout Malfunction Test Step 0 Ground connector socket No. 2 open. Open ckt in wire to socket No. 3 or No. 6 of diagnostic socket or on-off ratio tester defective. Mixture adjustment too rich. Repair as necessary 10 Airflow sensor position indicator polarity reversed or defective. Terminals of throttle valve switch polarity reversed or defective. Terminals of throttle valve switch connector (idle and full load contacts reversed or idle contact open with microswitch closed. 7.0-7.6, 5.0-5.3, 10.0-10.3, Repair as necessary 20 Full load contact defective or throttle valve switch polarity reversed. 20% displayed only with activated microswitch 5.0-5.3, Repair as necessary 30 Short or open ckt between CIS-E control unit and coolant temperature sensor or defective coolant temperature sensor, or excessive deviation in temperature values in comparison with EZL ignition control unit 6.0-6.3, Repair as necessary 40 Open or short in airflow sensor position indicator wiring or defective airflow sensor position indicator 7.0-7.6 50 O2 sensor not operational/defective, open ckt Repair as necessary 60 Unlikely speed signal at CIS-E control unit 11.0-11.2 70 Unlikely TNA-signal (RPM) at CIS-E control unit 8.0-8.1 80 Interrupted data exchange between EZL ignition control unit & CIS-E control unit 12.0 90 Unlikely current reading at EHA 4.0-4.4 95 Decel fuel shut-off valve in operation N/A 100 No voltage or ground at CIS-E control unit No voltage or ground at CIS-E control unit CIS-E control unit defective On-off ratio tester defective. Lambda adjustment too lean. O2 sensor defective (short to ground) Test Step 1.0-3.0, 14.0-14.7 Oscillates No malfunctions of the signals monitored N/A
Mercedes-Benz 300TE 4Matic 1990 COOLANT TEMPERATURE SENSOR SPECIFICATIONS
?F (?C) Ohms Volts at Socket -4 (-20) 15,700 3.24 - 3.94 14 (-10) 9200 2.84 - 3.47 32 (0) 5900 2.39 - 2.93 50 (10) 3700 1.94 - 2.37 68 (20) 2500 1.51 - 1.84 86 (30) 1700 1.16 - 1.42 104 (40) 1180 0.88 - 1.08 122 (50) 840 0.66 - 0.80 140 (60) 600 0.50 - 0.61 158 (70) 435 0.38 - 0.46 176 (80) 325 0.29 - 0.35 194 (90) 247 0.22 - 0.26
Mercedes-Benz 300TE 4Matic 1990 - CLEARING CODES
Each code stored in memory must be erased individually. After blink impulse (code) readout, wait 2 seconds then press push button for at least 6 seconds. LED will blink once, indicating code is erased. Continue until all codes are erased.
Mercedes-Benz 300TE 4Matic 1990 - TEST STEP CHARTS
Fig. 5: Mercedes-Benz 300TE 4Matic 1990 - Component Locations - Test Steps 1.0 Thru 4.3
Fig. 6: Mercedes-Benz 300TE 4Matic 1990 - Component Locations - Test Steps 4.4 Thru 6.2
Fig. 7: Mercedes-Benz 300TE 4Matic 1990 - Component Locations - Test Steps 6.3 Thru 9.2
Fig. 8: Mercedes-Benz 300TE 4Matic 1990 - Component Locations - Test Steps 10.0 Thru 13.0
Fig. 9: Mercedes-Benz 300TE 4Matic 1990 - Component Locations - Test Steps 13.1 Thru 14.6
Fig. 10: Mercedes-Benz 300TE 4Matic 1990 - Component Locations - Test Steps 14.7 Thru 16.3
Fig. 11: Mercedes-Benz 300TE 4Matic 1990 - Component Locations - Test Steps 16.4 Thru 17.3
Fig. 12: Mercedes-Benz 300TE 4Matic 1990 - Component Locations - Test Steps 18.0 Thru 19.4
Fig. 13: Mercedes-Benz 300TE 4Matic 1990 - Component Locations - Test Steps 20.0 Thru 23.2
Mercedes-Benz 300TE 4Matic 1990 - IMPULSE DISPLAY CODE CHARTS DISPLAY 1: NO SYSTEM MALFUNCTION,
See
Fig.14.
Mercedes-Benz 300TE 4Matic 1990 - DISPLAY 2: FULL LOAD CONTACT
See
Fig.14.
Mercedes-Benz 300TE 4Matic 1990 - DISPLAY 3: COOLANT TEMPERATURE SENSOR
See
Fig.14.
Fig. 14: Mercedes-Benz 300TE 4Matic 1990 - Component Locations - Impulse Display 1, 2 & 3
Mercedes-Benz 300TE 4Matic 1990 - DISPLAY 4: AIRFLOW SENSOR POSITION INDICATOR
See
Fig.15.
Mercedes-Benz 300TE 4Matic 1990 - DISPLAY 5: O2 SENSOR
See
Fig.15.
Fig. 15: Mercedes-Benz 300TE 4Matic 1990 - Component Locations - Impulse Display 4 & 5
Mercedes-Benz 300TE 4Matic 1990 - DISPLAY 6: NOT USED
See
Fig.16.
Mercedes-Benz 300TE 4Matic 1990 - DISPLAY 7: TD - SIGNAL
See
Fig.16.
Mercedes-Benz 300TE 4Matic 1990 - DISPLAY 8: ALTITUDE CORRECTION CAPSULE
See
Fig.16.
Fig. 16: Mercedes-Benz 300TE 4Matic 1990 - Component Locations - Impulse Display 6, 7 & 8
Mercedes-Benz 300TE 4Matic 1990 ALTITUDE CORRECTION CAPSULE
Altitude: Ft. (m) Pressure: In. Hg Volts 0 (0) 27.2 3-5 3281 (1000) 24.2 2-4 6562 (2000) 21.4 1-3
Mercedes-Benz 300TE 4Matic 1990 - DISPLAY 9: ELECTROHYDRAULIC ACTUATOR
See
Fig.17.
Mercedes-Benz 300TE 4Matic 1990 - DISPLAY 10: IDLE SPEED CONTACT
See
Fig.17.
Fig. 17: Mercedes-Benz 300TE 4Matic 1990 - Component Locations - Impulse Display 9 & 10
Mercedes-Benz 300TE 4Matic 1990 - DISPLAY 11: NOT USED
See
Fig.18.
Mercedes-Benz 300TE 4Matic 1990 - DISPLAY 12: EGR TEMPERATURE SENSOR
See
Fig.18.
Fig. 18: Mercedes-Benz 300TE 4Matic 1990 - Component Locations - Impulse Display 11 & 12
Mercedes-Benz 300TE 4Matic 1990 - SUMMARY
If no hard fault codes (or only pass codes) are present, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e. ROUGH IDLE, NO START, etc.) or intermittent diagnosis procedures.