500SL (129.067) V8-5.0L (119.960) (1990)
Engine Control Module: Customer Interest
Battery - Updated ECM and Alternator Pulley
REF. NO. MBNA 07.3/16a, 15/8a
TO:
OUR MERCEDES-BENZ PASSENGER CAR DEALERS
DATE:
March 1992 (supersedes MBNA 07.3/16, 15/8, October 1991)
Revision:
Change to assembly procedure
SUBJECT:
MODEL 129.066
1.
MODIFIED CIS-E CONTROL UNIT
2.
MODIFIED ALTERNATOR PULLEY AND FAN
To improve the charging characteristics of the vehicle's electrical system the engine idle speed is increased in relation to the battery voltage. Two
modifications have been introduced as a repair solution for vehicles up to chassis end number 032708. The installation of the new pulley and fan will
correct complaints of a discharging battery.
1.
Modified CIS-E Control Unit
As of chassis no. 032708, a new CIS-E control unit has been installed in production. This new control unit will raise the engine idle speed by
approximately 100 rpm during periods of low battery voltage, thus increasing the output of the alternator. The system will switch the idle speed increase
circuit on under the following conditions:
1.
Engine coolant temperature between 60~C (140~F) and 110~C (230~F),
2.
Transmission gear selector in a driving position, 3. Battery voltage is less than 12.5 volts for at least 20 seconds, 4. Engine speed rises above 900
rpm. (This is to prevent a sudden power surge that would be noticed if the engine were at idle.)
If the first 3 conditions are met, the CIS-E control unit enters that fact into memory, so that when the fourth condition is met, the idle speed increase
system will be switched on.
The increased idle speed setting will remain in effect until any one of the following occurs:
^
The transmission gear selector is placed in "N" or "P".
^
The engine coolant temperature exceeds 110~C (230~F).
^
The ignition is switched off.
The new control units may be installed in earlier production vehicles.
Parts Information
Part Name
Part Number
Federal version vehicles
012 545 22 32
California version vehicles
012 545 23 32
In Case of Warranty
Operation:
CIS-E control unit, install modified version according to S.I. MBNA 07.3/16a, 15/8a.
Damage Code
Operation Number
Time
Model(s)
54481**