Mercedes-Benz SLK 230 Cruise Control Switch Replacement

Applicable Models:

Mercedes-Benz SLK230 (1998-04)

Project Time: 2 hours
Tab: $153
Talent
Tools: Long T30 Torx driver, 10mm hex/Allen bit, socket extensions, breaker bar, Phillips screwdriver, side-cutters, small flat-blade screwdriver

Parts Required: Cruise control switch.
Performance Gain: Restores cruise control function.
Complementary Modification: Replace the steering wheel, tighten or replace the turn signal stalk.

Malfunctioning cruise control is more of an inconvenience than a deal-breaker for many SLK owners.

MB issued a Technical Service Bulletin (TSB) in 2004 regarding cruise control disengagement at highway speeds. The problem was traced to tires with uneven wear or differing diameters. Control-module programming was also mentioned as a potential source of the problem.

In the R170 SLK and other MB models, a switch on the steering column sends cruise control signals to the car's CAN data bus. In addition to the stalk/switch, the cruise control system also includes a control module and a servo. The Check Engine Diagnostic Trouble Code (DTC) for a cruise control switch problem is P0565.

Often, the gripe isn't a trouble code but a loose cruise control stalk. Its retaining screw can back out inside the steering column, and the stalk can even slide out of the locating slot in the column's collar.

Regardless of whether the cruise stalk is loose, broken, or dead, it can be repaired or replaced at home in a couple hours. The job requires removing the airbag, steering wheel, and lower interior panel. Details on these jobs are covered in other articles; highlights are rehashed here.

Like the turn signal/combination stalk, the cruise switch has a wiring harness that goes through the steering column's collar, under the dash, and plugs in to the terminal block near the headlight switch. Accessing the plug requires unscrewing the panel below the steering column. This requires undoing the OBD-II data port, the hood release latch, the upper left vent, and the headlight switch/fuse panel assembly.

The wiring harness/plug is soldered to the cruise control switch. The replacement part (210-540-07-45-MBZ) is a complete assembly, available from Pelican Parts.

Remember to disconnect the battery's negative cable and shield it from the battery post and allow the airbag's capacitor to discharge for at least 30 minutes before beginning.

Hot tip

Zip-tie the steering-angle sensor assembly together after unscrewing it; use new zip-ties to secure the cruise control wires.

Wayne R. Dempsey, Co-Founder & DIY Expert

Tom Morr, DIY Expert

Project Photos

Figure 1 An airbag misfire can be deadly. When disconnecting the battery to disable the airbag, make sure that the negative cable and battery post are separated and shielded. Then wait about 30 minutes for the airbag's capacitor to discharge.

Figure 2 A T30 Torx driver, ideally 2.5 inches or longer, is required for removing the airbag bolts through the two holes on the back of the steering wheel. MB makes a special bit, but this part-store set worked. After breaking the screws loose, the T30 bit was removed from the set to improve clearance at the steering column.

Figure 3 Using a small flatblade screwdriver if necessary, unplug the airbag (arrow), facing it toward the open door for peace of mind should it inadvertently detonate. Store it black-side up, out of the sun.

Figure 4 The steering wheel must be stabilized so that the force required to loosen its retaining screw (which takes a 10mm hex/Allen bit) doesn't damage the steering wheel's locking mechanism. Several forum posts report success using an impact gun. We used "armstrong" power on the wheel and knee force on a breaker bar.

Figure 5 After marking the steering wheel's position on the shaft and pulling the wheel off, the steering-angle sensor/clockspring assembly is revealed. Two Phillips screws (arrows) secure and orient it. The unit's wires plug into the steering wheel to ensure proper airbag and ESP function.

Figure 6 The ribbon inside the clockspring is calibrated. Consider securing its halves with a zip-tie so it doesn't come apart. The gray boots (green arrows) aren't plugs; let the clockspring hang. The cruise control stalk is held on by one Phillips screw (purple arrow). The other two screws (yellow arrows) secure the turn signal/combination stalk.

Figure 7 If the cruise control stalk is loose and/or improperly seated in the column's collar, remove the Phillips screw and groove the stalk in place. Consider using threadlocker on the screw prior to reinstallation to inhibit looseness later.

Figure 8 With the lower interior panel removed, carefully cut the nylon ties that secure the cruise control's wiring harness. Note the locations for proper routing and securing with new zip-ties during reinstallation.

Figure 9 The cruise control switch plugs into the terminal block's "G" slot. The block is to the left of steering column (left-hand drive cars), behind the lower panel.

Figure 10 To remove the cruise-control switch assembly, feed the wiring harness and plug out through the steering column. Removing the turn signal stalk (two screws) creates enough space for the plug to easily come through the column to the upper left of the steering shaft.

Figure 11 The replacement cruise control stalk/switch includes the harness and plug--the wires are soldered to the switch. Installation reverses the disassembly steps.

Comments and Suggestions

Daredevil6

August 24, 2016

Is there a trick to disconnecting the harness from the plug? It seems very difficult to pull apart, and I don't want to risk damaging either the harness or the plug in Block G.

Followup from the Pelican Staff:

There should be two tabs, squeeze them together and pull it straight apart. - Nick at Pelican Parts

Wavishing

August 13, 2016

No mention of the Kerr Nielson two pin cruise control switch,brake light switch or their locations. According to my local Mercedes agent these are more likely to be a problem rather than the operating stork mechanism.

Thanks for the additional info and feedback. We appreciate it. if we get the chance to add that info we will. - Nick at Pelican Parts