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Turn Signal Stalk and Combination Switch Replacement
 
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Pelican Technical Article:

Turn Signal Stalk and Combination Switch Replacement

Tom Morr

Time:

2 hours2 hrs

Tab:

$280

Talent:

**

Tools:

Long T30 Torx driver, 10mm hex, Allen bit, socket extensions, breaker bar, Phillips screwdriver, side cutters, small flathead screwdriver

Applicable Models:

Mercedes-Benz R170 (1998-04)

Parts Required:

Turn signal stalk (combination switch)

Hot Tip:

Allow the airbag to discharge for 30 minutes after disconnecting the battery

Performance Gain:

Restores turn signal and wiper functionality

Complementary Modification:

Replace the steering wheel, tighten or replace the cruise control stalk

A common annoyance with Mercedes-Benz cars in general and R170 SLKs in particular is floppy turn-signal stalks. Even when the stalks remain functional, their mounting screws can come loose inside the steering column.

Fortunately, the problem can be fixed at home. Devoting a couple hours to the job can yield a semi-permanent fix. And if any of the functions controlled by the turn signal stalk (technically known as the Combination Switch) are toast, the stalk replacement procedure adds a few steps to the job.

Getting to the stalk/switch consumes the bulk of the time. First, disconnect the battery and wait about 30 minutes. This allows the airbag to discharge.

Other preliminary steps include removing the steering wheel, airbag, contact spiral clock spring, and, if the stalk needs to be replaced, unscrewing the lower interior panel. (See those articles for details; highlights are shown below.) Some Mercedes-Benz models have a plug inside the steering column collar for the turn signal/combo switch; the R170 switch has a harness that plugs into a junction block beneath the headlight switch.

For reinstallation, many SLK owners add dollops of thread-locker to the mounting screws to prevent the stalk from vibrating loose again. The cruise control stalk shares a mounting screw with the turn signal stalk, so it gets tightened in conjunction with this job.

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. Also, if the OE radio is still in the car, its security code will need to be re-entered after the battery is reconnected. Installation steps reverse the disassembly.

The turn signal stalk/switch has an integrated wiring harness. The replacement part (170-540-01-44-MBZ) comes as a complete assembly, available from Pelican Parts.

Disconnect the battery, and make sure that the negative cable is shielded from the battery terminal.
Figure 1

Disconnect the battery, and make sure that the negative cable is shielded from the battery terminal. Then wait about 30 minutes for the airbag's capacitor to discharge to prevent accidental deployment.

Mercedes-Benz offers a special T30 Torx driver for removing the airbag, but a parts store set will work as long as long as the T30 wrench at least 2.
Figure 2

Mercedes-Benz offers a special T30 Torx driver for removing the airbag, but a parts store set will work as long as long as the T30 wrench at least 2.25 inches long.

Unplug the airbag wiring connection (green arrow).
Figure 3

Unplug the airbag wiring connection (green arrow).

If available, have an assistant hold the steering wheel steady while using a breaker bar on a 10mm hex/Allen bit to unscrew the wheel.
Figure 4

If available, have an assistant hold the steering wheel steady while using a breaker bar on a 10mm hex/Allen bit to unscrew the wheel. The steering wheel lock can break if the wheel isn't supported against the force necessary to loosen the retaining screw.

Mark the steering wheel's position on the shaft and pulling the wheel off.
Figure 5

Mark the steering wheel's position on the shaft and pulling the wheel off. The steering-angle sensor contact spiral/clock spring assembly is held on with two Phillips screws (green arrows).

The ribbon inside the clock spring is calibrated.
Figure 6

The ribbon inside the clock spring is calibrated. Consider securing its halves with a zip-tie so it doesn't come apart. If the turn signal stalk/combination switch is loose, simply tighten the three Phillips screws (yellow arrows). The lower left dash panel won't need to be removed.

If the stalk/switch is bad, remove the lower dashboard panel (please see that article for details).
Figure 7

If the stalk/switch is bad, remove the lower dashboard panel (please see that article for details). Follow the wiring harness to the black plug in the "H" slot, the far right one in the junction block. Carefully snip the zip ties that secure the harness.

Slide the plug out of the junction block.
Figure 8

Slide the plug out of the junction block. The plug's halves are connected by a slide-lock bar (arrow).

The cruise control stalk and combination switch share a screw (arrow).
Figure 9

The cruise control stalk and combination switch share a screw (arrow). Remove it and set the cruise stalk off to the side.

Remove the remaining two Phillips screws (arrows) to free the stalk/combo switch.
Figure 10

Remove the remaining two Phillips screws (arrows) to free the stalk/combo switch.

The stalk comes out by fishing the harness and plug through the column's collar.
Figure 11

The stalk comes out by fishing the harness and plug through the column's collar. Installation reverses the disassembly.

In the R170 SLK, the combination switch has an integral harness and plug, which adds a few steps to the R&R process compared to models where the switch plugs in to the steering column.
Figure 12

In the R170 SLK, the combination switch has an integral harness and plug, which adds a few steps to the R&R process compared to models where the switch plugs in to the steering column.

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Comments and Suggestions:
jim Comments: We gave up, the wiring harness is held in place by the clock spring and the "L" shape wiring prong would not come out without the clock spring removed.

Hard to believe that somebody has not been into a 2006 SLK before now.
July 5, 2016
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 
jim Comments: The 2006 SLK 240 clock spring is a bit different, ours appears to be hard wired thru an "L"shaped plastic appendage that runs down inside the column.

Does this '06 clock spring remove by simply pulling up and out
or do you have to remove some other parts?
June 27, 2016
  Followup from the Pelican Staff: You will have to, at them minimum, detach the wiring harness to the part you are referring to. We don't have an 06 240 here in the US. You may have to remove the entire switch assembly, if it is similar to our models. - Nick at Pelican Parts  
Stevie Comments: Thank goodness fro your instructions. Just finished replacing this turn signal switch.
November 29, 2015
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 

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