300E (124.030) L6-3.0L (103.983) (1986)
Technical Service Bulletin # 07.3_004
Date: 860601
CIS-E Control Unit - Update Diagnostics
TO:
OUR MERCEDES-BENZ PASSENGER CAR DEALERS
DATE:
June 1986 REF.NO. MBNA 07.3/4
SUBJECT:
CIS-E FUEL INJECTION SYSTEM MODEL 300E (124.030)
A modified CIS-E control unit is installed in these vehicles since the beginning of January 1986. This control unit contains a microprocessor which
permits on-board diagnostic readout via the on-off ratio tester similar to engines 116/117.
A revised CIS-E Injection System Test is enclosed with this Service Information. In order to determine if a vehicle is equipped with a CIS-E control unit
with or without on-board diagnostic readout feature, refer to the attached CIS-E Injection System Test.
The previous CIS-E control unit and the new control unit are interchangeable. The part no. was not changed.
Testing Electrical Components of the CIS-E Injection System
This test program is divided into the following sections:
A)
On-board diagnostic readout via on-off ratio tester
B)
Testing and adjusting lambda control
C)
Testing, electronic idle speed control
D)
Testing cold start valve activation
E)
Testing deceleration shutoff
F)
Testing idle and full load contacts
G)
Testing overvoltage protection relay
Note:
When testing the CIS-E injection system at lower altitudes (sea level), on vehicles with early CIS-E control units of the new version (Bosch production
code 641 and 642), it is possible that the on-off ratio tester indicates a fixed reading of 80%, indicating a failure of the altitude correction capsule. The
lambda system, however, works properly.
In this case, proceed as follows:
Test altitude correction capsule according to on-off ratio 80% in section A "On-board diagnostic readout via on-off ratio tester. If no failure is indicated,
apply manifold vacuum to the altitude correction capsule by pulling off the vacuum line from the intake manifold at cylinder no. 6 and connecting a Y
distributor instead. Then reconnect the vacuum line and connect the altitude correction capsule with a second vacuum line. The on-off ratio reading must
oscillate. Check onoff ratio and adjust if required. (See Section B "Testing and adjusting lambda control").
SPECIAL TOOLS
Special Tools
On-off ratio tester
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