Cruise Control - Amplifier, Update and Resistance Specs

REF.NO.
54/42



TO:
OUR MERCEDES-BENZ PASSENGER CAR DEALERS

DATE:
September 1987



SUBJECT:
A. MODIFIED CRUISE CONTROL AMPLIFIER MODELS 107.048, 126.035/.037/.039/.044/.045, 201.029/.128

B. DOWNHILL SURGING MODELS 201.122/.126



A. Modified Cruise Control Amplifier Models 107.048, 126.035/.037/.039/ .044/.045, 201.029/.128





A cruise control amplifier with reference resistor is now installed in these vehicles (Fig. 1). The amplifier is the same for all models; through the use of the reference resistor, the amplifier can be modified/adapted to each particular model. For additional function information refer to p. 229 of the introduction manual model Year 1987, models 107,124,125 & 201. For reference resistor application, see Parts Information.


Effective Serial Number


Model As of

107.048 January 1987
126.03/.04 January 1987
201.029/.128 Prod. start-up





For easier identification, the last four digits of the reference resistor part number are enlarged (arrow, Fig. 2).






In case of customer complaints regarding the cruise control, the reference resistor (Fig. 3 and 4) must be tested with a multimeter as outlined below, before replacing the cruise control amplifier.

Note:
On some reference resistors the socket designations, A-G, are not shown (c, Fig. 4). Be sure to test the resistor as pictured in Figure 4.


Test Procedure

1. Remove reference resistor from cruise control amplifier.

2. Connect multimeter, switch to Ohm scale.

3. Test resistance values (see table) If values deviate from table, replace reference resistor.





Reference Resistance Test Values



Equipment


Multimeter 1) SUN DMM-5

1) Available through the MBNA standard Equipment Program


B. Downhill Surging, Models 201.122/.126

On these models, the reference resistor with amplifier (see parts information) may be used to reduce or eliminate downhill surging. Before installing the amplifier, the linkage must first be disassembled, cleaned, lubricated and then adjusted (as described on P.84 in Model 201 section of the introduction manual, Model Year 1984). Check that the linkage is not worn and that it moves freely throughout its entire range.





Parts Information



Note:
After stock depletion, only the modified cruise control amplifier and individual reference resistors will be available.

Note:
When replacing the cruise control actuator, refer to the guidelines in S.I. 54/34a, September 1985.