Engine - Surging During Cruise Control Operation

88mercedes01

TO: OUR MERCEDES BENZ PASSENGER CAR DEALERS

DATE: January 1988 REF. NO. MBNA 07.1/15,54/15


SUBJECT: ENGINE SURGING DURING CRUISE CONTROL OPERATION 124.133/.193 AND 126.125
MODEL YEARS 1986 AND 1987


In case of customer complaints regarding engine surging under load during cruise control operation, install a vacuum damper with orifice according to the procedure below.

FIGURE 1:

Procedure

Model 124

1. Mount switchover valvemicroswitch (Y30/1) onto the firewall at the left side of the engine compartment next to the vacuum amplifier switchover valve (Y29). For this purpose, move the vacuum amplifier switchover valve (Y29) to the left (Figure 1).

FIGURE 2:

Model 126

1. Mount switchover valvemicroswitch (Y30/1) onto the firewall at the left rear of the engine compartment next to the engine overload protection switchover valve (Y30, Figure 2).

FIGURE 3:

2. Connect vacuum lines (6 and 10), vacuum reservoir (9/1) and orifice (61c) to switchover valvemicroswitch (Y30/1).

FIGURE 8 - VACUUM LINE LAYOUT, MODELS 124/126:

For complete vacuum diagram, page 4.

FIGURE 4:

Model 124

3. Fasten vacuum reservoir (9/1) to preglow wiring harness bracket with tie-down straps (Figure 4).

FIGURE 5:

Model 126

3. Fasten vacuum reservoir to fuel wiring harness bracket with tie-down straps (Figure 5).

FIGURE 6:

4. Fabricate a wiring harness according to the sketch below (all dimensions in mm).

FIGURE 7:

5. Connect harness according to wiring diagram (Figure 7). Solder short wire to terminal 2 (bk/rd) of the plug connection for the engine overload protection switchover valve (Y30). Solder long wire to terminal 2 (br/rd) of the plug connection for the A/C compressor shutoff microswitch (S27/1). Connect 2-pole plug to switchover valve-microswitch (Y30/1).

FIGURE 9:

Parts Information

Note: Please refer to the above figure



Time Allowance
Damage Code

54603 62 Vacuum damper with orifice, retrofit