300E (124.030) L6-3.0L (103.983) (1986)
e
Wire connector, circuit 30 (fuse and relay box)
f
Fuse 9, circuit 30
9
Plug connection, starter lockout switch
(terminal 4)
h
Starter lockout switch (terminall)
i
Automatic transmission
Plug connection, starter lockout switch (terminal 3), circuit 50
Manual transmission, engine ground (via starter coil)
k
Fuse 6, terminal 15
l
Auxiliary fan relay, circuit 86
x
Pressure switch, A/C compressor
Note:
Unmarked ground connections are grounded on engine or chassis. The wire on terminal 6 (circuit 87 K) on the fuel pump relay connector does not apply
to vehicles with manual transmission.
On-Board Diagnostic Readout Via On-Off Ratio Tester
Since January 1986 production, a CIS-E control unit with microprocessor is installed which permits failure diagnosis by measuring the on-off ratio
(similar to engines 116 and 117). The failure codes are transmitted via the Lambda measuring circuit of the diagnostic socket and are shown on the
on-off ratio tester. The fixed on-off ratio indicates possible malfunctions. The following table gives the relationship between the fixed on-off ratio, the
cause of the failure and the respective component test to be performed.
Note:
This test program is also applicable to vehicles produced until the end of December 1985. In this case, start testing with section 1. Testing voltage supply
to CIS-E control unit and continue with the following sections until the failure is located.
CONNECTION OF ON-OFF RATIO TESTER
In order to determine if a vehicle is equipped with a CIS-E control unit with or without microprocessor, proceed as follows:
Connect on-off ratio tester to diagnostic socket. Turn ignition "ON".
Needle indication
CIS-E control unit
70%
with failure code feature
100%
without failure code feature
Connection of on-off ratio tester
N3
CIS-E control unit
P
On-off ratio tester
X11
Diagnostic socket
Test condition:
Check all on-off ratio values with engine running at idle speed and engine oil temperature between 60~C (140~F) and 80~C (176~F).
Fixed
on-off
Possible cause of failure
Tests to be performed
ratio %
0%
CIS-E control unit receives no voltage or
Check voltage supply, ground connection