Engine Controls - Electronic Throttle EML Functions

89BMW08

Group 12 Engine - Electrical
Bulletin Number 12 11 89 (1982) Page 1 of 3
Woodcliff Lake, NJ November 1989 Technical Dept.
SUBJECT: EML System Diagnosis

MODEL: 750iL

Situation: All functions of the electronic throttle control are continuously self-checked by the EML Control Unit. When a fault is detected, it is assigned a fault code and stored in the EML fault memory according to priority and frequency.

Fault codes 1 through 7 do not affect EML reliability; therefore they do not activate the EML emergency program.

Fault codes 8 through 22 trigger the EML emergency program which limits the throttle opening and illuminates the EML fault lamp.

Prior to any EML troubleshooting or repairs, the EML fault memory must be called up and printed (see S.I. 12 09 88 (1719).

Special
Note: The EML fault memory is maintained by a trickle current through the EML warning lamp. The EML fault memory is cleared whenever the vehicle battery is disconnected or when the instrument cluster is unplugged.

Certain basic faults can have an effect on the EML system causing the system to switch over to the emergency program.

The following points should be considered whenever unusual EML operation is encountered.

- The vehicle battery state of charge and specific gravity must be as specified with tight and clean battery terminal connections.

Open circuit voltage = 12.5 volts and above

Specific gravity = 1.260 @ 80~F
- If the battery has a low state of charge, check the following points:

Has the low speed operation (smaller) alternator pulley been installed? See S.I. 12 08 89 (1959) for details.

Check for equipment which may increase the vehicle's electrical load or increase the residual current draw if left switched ON e.g. telephones, C.B. radios, radar detectors etc.

- The 50A fuse link (in shrink tubing) near the battery must be free of dynamic resistance. Use the voltage drop method for testing.

All primary positive and negative connections must be clean and tight. This applies particularly to the positive junction (X1.0) under the pedal assembly (see S.I. 61 04 88 (1619).

- Multiplug connections should be examined for loose pins or moisture corrosion. This is especially true of engines which have been subjected to high pressure washing (see S.I. 12 03 89 (1838).

- The engine wiring harness should be examined for damage. Remove covers as needed and move harness.

- Using the diagnostic module, call up the identification pages of the
DME, EML and AEGS system. Verify that the control units are correct, compatible and that the EML control unit has the latest software.

- The fuel pressure must be within specifications. Two gauges should be used to check both fuel systems simultaneously.

Nominal 3.0 bar, vacuum line disconnected.

- Compare the secondary ignition pattern of each cylinder bank and verify that they are identical. Spark line variation can indicate distributor rotor adapter faults (see S.I. 11 10 89 (1794).

- The control circuits (multiplug position # 4) of both main relays must be bridged (see S.I. 12 07 89 (1921) for details).

- The engine must be free of unmetered air leaks. Compare the manifold vacuum of both cylinder banks.

If one or both DK motors are replaced, the EML system must be synchronized per the procedure listed in S.I. 12 06 88 (1669).
Warranty
Information: These specified measures are intended as a reminder and are not repair instructions. The BMW troubleshooter should consider these points in cases where the EML fault eludes normal fault finding techniques.