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M 3.1 Engine Control Modules (12 08 91 (3409))

Publication date: 1992-06-01
Reference number: 12 08 91 (3409)
Supersedes refnos: 12 01 92 (3840)

M 3.1 ENGINE CONTROL MODULES

M 3.1 ENGINE CONTROL MODULES

TECHNICAL SERVICE BULLETIN

Reference Number(s): 12 01 92 (3840), 12 08 91 (3409)

M 3.1 ENGINE CONTROL MODULES

Model(s): 1991-92 BMW 525i (E34), 325i (E36) w/ M50 Engine

Group: 12 - Engine Electrical

Bulletin No.: 12 08 91 (3409)

Date: June, 1992

NOTE: This Service Information Bulletin supersedes S.I. 12 08 91 (3409) dated November 1991 and S.I. 12 01 92 (3480) dated February 1992. It includes instructions on Service Action code numbers 65, 70, and 74.
NOTE: The procedure outlined in this service information bulletin should be performed on all affected vehicles whenever such vehicle is in the shop for maintenance or repair.

VEHICLES AFFECTED

Due to the overlapping production ranges involved, a particular vehicle may require the completion of more than one of the Service Actions outlined in this bulletin. In order to determine if a specific vehicle is affected by one of these Service Actions, it will be necessary to utilize the "Service Menu" of DCS (Dealer Communication System). Proceed to item #6 "Vehicle History Inquiry" and enter the Chassis Number (last seven characters) of the vehicle in question. Based on the response of the system, either proceed with the required corrective actions or take no further action.

The Chassis Number Ranges listed below are only for informational purposes and are not to be considered as the only deciding factor. The affected vehicles are limited lo vehicles within these ranges, but not all of these vehicles arc affected by every Service Action outlined in this bulletin. The final decision factor is the DCS inquiry.

MODEL CHASSIS NUMBER RANGES

MODEL CHASSIS NUMBER RANGES

Model Chassis Number Ranges
325i (E36) 2dr EF 35008 - EF 35622
325iA (E36) 2dr EK 00008 - EK 01145
325i (E36) 4dr FE 00004 - FE 05966
325iA (E36) 4dr FF 75005 - FF 89530
525i (E34) BF 94002 - BF 98128
525iA (E34) BJ 57004 - BJ 76644
525i/A (E34) GD 20001 - GD 20004

SITUATION

Vehicles within the production ranges listed below may be affected by one or more of the following conditions.

CASE 1 (E36 M50 VEHICLES PRODUCED BETWEEN 8/91 AND 10/91)

Due to an engine control module with an overly Sensitive On-Board Diagnostic System, the CHECK ENGINE light may flicker upon load reversal at high engine RPM. Additionally, one or both of the following fault codes may be stored in the fault memory of the transmission control module or engine control module.

  1. On automatic transmission vehicles there is a failure in communication between the transmission and engine control modules. Fault code 104 (Temperature Failure) will be set in the transmission control module.
  2. On both automatic and manual transmission vehicles, fault code 41 (Mass Air Flow Sensor-short to B+) will be set in the engine control module. although there is no problem with the mass air flow sensor or its wiring.

SOLUTION 1

Vehicles having an engine control module with BMW Hardware Numbers 1 738 376 of 1 738 931 are to receive a replacement engine control module as outlined in the procedures contained in this bulletin.

CASE 2 (E34 AND E36 M50 VEHICLES PRODUCED IN 12/91 AND 1/92)

Due to an internal programming inconsistency, at irregular intervals the status registers for idle adaptation are cleared. This causes the vehicle to return to its programmed base idle and re-adaptation of the idle in response to the present operating conditions. Due to the speed at which this process is performed, this condition will not be perceived by the driver.

SOLUTION 2

Vehicles having an engine control module with BMW Hardware Number 1 748 037 and a Bosch production date code of 172 or 261 (EXCEPTIONS - 261 with blue dot on connector face is OK; 172 or 261 with Bosch Remanufacturing Stamp is OK) are to receive a replacement engine control module as outlined in the procedures contained in this bulletin.

CASE 3 (E34 AND E36 M50 VEHICLES PRODUCED BEFORE 11/91)

Failure of the oxygen sensor is possibly due to "thermal shock". Thermal shock may occur only under certain environmental conditions when a cold engine is started and moisture/condensation in the exhaust passes over the heated oxygen sensor causing a rapid cooling of the sensor's outer ceramic shell. This rapid cooling may cause the ceramic shell to shatter or crack.

Complaints may be received of the CHECK ENGINE light illuminating while driving with a possible rough running condition. Fault codes 70 and/or 201 may also be stored in the engine control module's fault memory, indicating an oxygen sensor fault.

SOLUTION 3

A brief delay function for the activation of the oxygen sensor healer relay has been incorporated into the latest version engine control modules. The engine control module on the affected vehicles is to be updated with this feature by recoding with a special MoDiC download diskette "Re-coding DME M3.1 M50 Version 2.0) as outlined in the procedures contained in this bulletin.

CASE 4 (E36 M50 VEHICLES FROM SERIES INTRODUCTION THROUGH 11/91)

Water may enter the oxygen sensor harness connector producing a short across the terminals resulting in an incorrect signal from the oxygen sensor. Fault codes 70 and/or 201 may also be set in the engine control module's fault memory, indicating an oxygen sensor fault.

SOLUTION 4

The oxygen sensor harness connector on the affected vehicles is to be sealed as outlined in the procedures contained in this bulletin.

CASE 5 (E34 M50 VEHICLES FROM SERIES INTRODUCTION TO 2/92)

Complaints may be received of the CHECK ENGINE light illuminating while driving with a possible rough running condition. Fault codes 70 and/or 201 may also be stored in the engine control module's fault memory, indicating an oxygen sensor fault.

SOLUTION 5

Incorrect routing of the oxygen sensor harness may lead to an internal break in the wire(s) causing the above situation. Affected vehicles are to have the oxygen sensor harness re-routed as outlined in the procedures contained in this bulletin.

REPAIR PROCEDURE

The flow chart (shown in Fig 1 ) is intended to guide the technician through the successful completion of Service Actions 65, 70, and 74.

Fig 1: Flowchart for Service Action 65, 70 & 74 - Attachment I
G93G58632

PARTS INFORMATION

Initial orders for 3-Series engine control modules will be filled using the following part numbers until stock is depleted:

PARTS INFORMATION

Model Trans. Part Number BMW HW# Bosch HW#
325iA 2/4 dr Automatic 12 14 1 738 848 1 748 037 0 261 200 402
325i 2/4 dr Manual 12 14 1 738 840 1 748 037 0 261 200 40

Once stock of the above part numbers is depleted, subsequent orders for 3-Series engine control modules and all orders for 5-Series engine control modules will be filled using the following part numbers:

PARTS INFORMATION

Model Trans. Part Number BMW HW# Bosch HW#
325iA 2/4 dr Automatic 12 14 1 748 238 1 748 401 0 261 200 402
325i 2/4 dr Manual 12 14 1 748 230 1 748 401 0 261 200 402
525iA/itA Automatic 12 14 1 748 240 1 748 401 0 261 200 402
525i Manual 12 14 1 748 234 1 748 401 0 261 200 402

Insulating Kit for Oxygen Sensor Connector on Vehicle Wiring Harness - E36 only:

Part Number for insulating kit - 11 78 9 064 612

NOTE: Engine control modules with BMW Hardware Number 1 748 401 will NOT produce accurate readings under "Status Calls" of the diagnostics. This is due to an error in the diagnostic software and not indicative of a defective control module and therefore does not justify replacement. This condition will be corrected in the next version of the Diagnostic Software. For further information on the errors in the "Status Calls" list, please refer to BMW Service Bulletin IDC 007/92-2. As we will be re-programming engine control modules with these faults, once the Warranty Parts Return Tag is printed out at the dealership the engine control module should be returned immediately to the following address:

DME Exchange

Warranty Parts Return Center

1 BMW Plaza

Montvale, NJ 07645

Pre-printed return shipping labels will be included with replacement engine control module orders, Please DO NOT affix this label to the engine control module.

Only engine control modules replaced for the above faults relating to action should be returned under this address. Engine control modules which failed for other reasons should be returned through normal channels.

SERVICE ACTION LABEL INSTRUCTIONS

The procedures outlined in this bulletin cover Service Action 65, 70, and 74, After the vehicle has been checked, and corrected if necessary, obtain a label (SD 91-013) and:

A.) Emboss your BMW dealer warranty number in the middle of the label,

B.) Punch Out the Service Actions completed based on the DCS system "Vehicle History Inquiry". This bulletin covers Service Actions 65, 70. and 74 (more than one may apply)

C.) Bend label to crease an edge and remove the backing paper, then affix it to the "B" pillar as shown in Fig 2 .

Fig 2: Service Action Label Application
G93H58633

If the vehicle already has a label from a previous Service Action/ Recall Campaign, affix this label next to the old one. Do not affix one label on top of another one because a number from an underlying label could appear in the punched out hole of the new label.

REPROGRAMMING ENGINE CONTROL MODULE USING MoDiC RECODING DISK

NOTE: The vehicle's battery must be sufficiently charged (>12.1 volts).

REPAIR PROCEDURE

  1. Verify engine control module Bosch Hardware Number is 0 261 200 403 or 0 261 200 405 (only these Bosch Hardware Numbers are affected).
  2. Read out fault memory and erase any fault codes stored.
  3. Load re-coding program into the BMW MoDiC via the BMW Service Test (use the same secret number assigned to your dealership for previous MoDiC download disks).
  4. Connect MoDiC to the diagnostic connector in the engine compartment.
  5. Switch on the ignition.
  6. Select "Recoding DME" from the main menu.
  7. Confirm "DME M3.1 M150 Version 2.O" by pressing right arrow key.
    1. If the engine control module has previously been recoded or does not require recoding, the following message will appear on the MoDiC display: "Measure not applicable to this control module version."
    2. If this message appears, exit recoding program by pressing the "up" arrow key to return to the main menu: no further action is required.
  8. Enter vehicle's mileage and confirm by pressing the "acknowledge" key.
  9. Start automatic re-coding by pressing the "acknowledge" key. The display will read "DME automatic recoding active, please wait". During the recoding process, a bar graph indicates the amount of data already transmitted; recoding process takes approximately one (1) minute.
  10. If the recoding process is completed successfully, the display will read "DME recoding completed"; return to the main menu by pressing the "up" arrow key.
  11. Switch off ignition.
  12. Disconnect MoDiC from the diagnostic connector and re-install the diagnostic connector cap.
  13. Wait at least 10 seconds prior to starting engine.

SEALING OF OXYGEN SENSOR CONNECTOR ON VEHICLE WIRING HARNESS (E36)

  1. Disconnect oxygen sensor harness connector from vehicle harness connector and remove vehicle harness connector from support bracket. The following steps outline the replacement of the multi-plug connector on the vehicle harness.
  2. Pull back the rubber boot on the vehicle harness multi-plug. Insert a small straight blade screwdriver into the slot on each side of multi plug to release locking collar. See Fig 3 .
    Fig 3: Releasing Locking Collar
    G93I58634
  3. Remove electrical connectors with BMW Special Tool 88 88 6 611 110. Refer to S.I. 04 06 87 (1357). See Fig 4 .
    Fig 4: Removing Electrical Connectors from Multi-Plug
    G93J58635
  4. Cut off all electrical connectors and remove rubber boot. See Fig 5 .
    Fig 5: Removing Electrical Connectors
    G93A58636
  5. Trim back the harness sheath (rubber insulating hose only) approximately 70 mm. See Fig 6 .
    Fig 6: Trimming Harness Sheath
    G93B58637
  6. Assemble adhesive profile and heat shrink tubing supplied in the kit over harness end (as shown in Fig 7 ) approximately 30 mm from end of harness. Apply heat until adhesive is clearly seen to seep out at both ends of heat shrink tubing.
    Fig 7: Assembling Adhesive Profile
    G93C58638
  7. Install new rubber boot supplied in the kit onto harness. External snap ring pliers (BMW Special Tool 88 88 6 232 200 or similar) may be used to assist in opening the end of rubber boot to insert harness. See Fig 8 . Exercise care so as not to damage the rubber boot with the plier tips.
    Fig 8: Opening End of Rubber Boot
    G93D58639
  8. Strip approximately 5 mm of insulation off end of each wire and install new electrical connectors supplied in the kit. The wire stripper on BMW Special Tool 81 24 9 408 125 will strip off the required amount of insulation and the crimper end of this tool will secure the electrical connector. See Fig 9 .
    Fig 9: Installing New Electrical Connectors
    G93G58640
  9. Insert electrical connectors into new multi-plug connector supplied in the kit as follows (refer to Fig. Fig 10 ):
    MULTI-PLUG ELECTRICAL CONNECTORS

    Pin Number Wire Color Function
    1 Black Sensor Ground
    2 Yellow Sensor Signal
    3 Brown Heater Ground
    4 Green/blue Heater B+
    Fig 10: Installing Electrical Connectors into Multi-Plug
    G93H58641
  10. Ensure electrical connectors are fully engaged in multi-plug housing, then engage secondary lock.
  11. Slide rubber boot into position on harness and place over end of multi-plug housing. See Fig 11 .
    Fig 11: Installing Rubber Boot
    G93I58642
  12. Re-install vehicle harness connector into support bracket and re-connect oxygen sensor harness connector to vehicle harness connector.

RE-ROUTING OXYGEN SENSOR HARNESS (E34 VEHICLES WITH M50 ENGINE)

  1. With the oxygen sensor harness guide rail removed, position the harness to form a wire loop above the sensor as shown in Fig 12 . This will give the harness enough slack to allow for exhaust system movement; i.e. expansion, contraction, vibration, etc..
    Fig 12: Oxygen Sensor Harness Routing
    G91G31977
  2. Fasten the wire harness in the two existing wire hold down clips.
  3. Secure the oxygen sensor harness guide rail to the body.
    • Bosch Production Date Code Location and Remanufacturing Stamp - Identification and Location (refer to Fig 13 )
      Fig 13: Date Code and Re-Manufacturing Stamp Location
      G93J58643
    • Example shown in Fig 13 has BOSCHDate: code 171.10 171 denotes month/year, 10 denotes day of month

Engine control modules with BMW Hardware Number 1 748 037 and a BOSCH date code of 172 or 261 are to be replaced.

EXCEPTIONS
  • An engine control module with a BOSCHDate: code of 261 AND a BLUE dot on the connector face is OR and is not to be replaced.
  • An engine control module with a BOSCHDate: code of 172 or 261 AND a BOSCH re-manufacturing stamp is OK and is not to be replaced.
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