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Turn Signal, Dimmer, Wiper Switch Replacement
 
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Pelican Technical Article:

Turn Signal, Dimmer, Wiper Switch Replacement

Steve Vernon

Time:

2 hours2 hrs

Tab:

$130

Talent:

**

Tools:

T-27 Torx, 10mm Allen with a breaker bar, Phillips screw driver

Applicable Models:

Mercedes-Benz W124 (1986-95)

Parts Required:

Turn signal, dimmer, wiper combination switch

Hot Tip:

Have someone hold the wheel when loosening main bolt

Performance Gain:

Working switches

Complementary Modification:

Replace cruise control switch

The turn signal, dimmer and wiper combo switch is located on the steering column and is attached to the steering shaft. To replace it you first need to remove the steering wheel. The wiring for the switch connects behind the lower dash. To get access to the connection you will also need to remove the lower dash.

Locate the negative terminal on the battery (yellow arrow) and remove the negative ground cable (red arrow).
Figure 1

Locate the negative terminal on the battery (yellow arrow) and remove the negative ground cable (red arrow). Place the cable in a manner that it cannot come in contact with the battery while working. Allow the car to sit for at least 15 minutes before working further on it to allow any remaining electrical energy in the car to dissipate.

The steering wheel has an air bag that will need to be removed before the wheel can come off (red arrow).
Figure 2

The steering wheel has an air bag that will need to be removed before the wheel can come off (red arrow).

Use a T-27 and loosen both screws that hold the airbag unit on (red arrow).
Figure 3

Use a T-27 and loosen both screws that hold the airbag unit on (red arrow). The screws are on each side of the back of the wheel at 3 and 9 o'clock. If the handle on your Torx driver is too long, try turning the wheel or even removing the lower dash cover to give you more room.

In this photo you can see the T27 wrench that I removed from the holder to make it easier (red arrow).
Figure 4

In this photo you can see the T27 wrench that I removed from the holder to make it easier (red arrow). With both screws loosened you can pull the airbag forward away from the wheel (yellow arrow). Note: the key is in the ignition so the steering wheel can be turned but the battery has been disconnected for at least 15 minutes before we started working on the airbag (green arrow).

Pull the airbag unit from the wheel and disconnect the plug (red arrow).
Figure 5

Pull the airbag unit from the wheel and disconnect the plug (red arrow). Always store the airbag unit with the logo or padded side facing up. The two screws that hold the bag to the wheel will remain in the wheel (yellow arrow, one shown).

The wiring connection for the horn and airbag does not disconnect from this point (yellow arrow).
Figure 6

The wiring connection for the horn and airbag does not disconnect from this point (yellow arrow). You will need to remove wheel, ring and lower dash. Disconnect the two horn wires (red arrows).

Use a 10mm Allen socket along with a breaker bar to loosen the single screw holding the wheel to the shaft (red arrow).
Figure 7

Use a 10mm Allen socket along with a breaker bar to loosen the single screw holding the wheel to the shaft (red arrow). Do NOT use the steering lock to help break the nut loose. Make sure to have someone hold the steering wheel stationary while breaking the bolt free.

There are witness marks on both the steering wheel (red arrows) and the shaft (yellow arrows) to make sure everything lines up when reassembling.
Figure 8

There are witness marks on both the steering wheel (red arrows) and the shaft (yellow arrows) to make sure everything lines up when reassembling. If yours are faded make your own marks with some white out or nail polish.

Pull the wheel straight back and off the shaft.
Figure 9

Pull the wheel straight back and off the shaft. The steering angle sensor will remain on the shaft.

To remove the steering angle sensor use a Philips head screwdriver and remove the two small screws (red arrows).
Figure 10

To remove the steering angle sensor use a Philips head screwdriver and remove the two small screws (red arrows). Use caution when pulling it off the steering shaft to remove it as one piece. If you separate the two plates the wiring will spool out and it is not easy to get it back in.

The wiring connection for the steering sensor will not separate from the back of the sensor (red arrow) and will stay attached while removing the cruise control switch.
Figure 11

The wiring connection for the steering sensor will not separate from the back of the sensor (red arrow) and will stay attached while removing the cruise control switch.

The wiring connects up under the dash.
Figure 12

The wiring connects up under the dash. You will need to remove the lower dash (red arrow) to get access to the connections. Please see our article on lower dash removal for further assistance.

Remove the three Philips head screws holding the switches to the shaft (red arrows).
Figure 13

Remove the three Philips head screws holding the switches to the shaft (red arrows). Slide the switch assembly and shaft collar forward and off the steering shaft.

The wiring harness runs down the steering column (yellow arrow) and across the knee beam to connect below the engine control module (red arrow).
Figure 14

The wiring harness runs down the steering column (yellow arrow) and across the knee beam to connect below the engine control module (red arrow).

Slide the wiring connection out from the bracket below the engine control unit and separate the connections by pulling them apart (red arrow).
Figure 15

Slide the wiring connection out from the bracket below the engine control unit and separate the connections by pulling them apart (red arrow). You will need to remove the engine control unit to pass the wiring through. Turn the knob on the unit (yellow arrow) which will move the unit forward and then pull it from its mount.

You will need to slide the steering column cover forward to cut the zip tie connection for the cruise control and turn signals located under the steering shaft (red arrow).
Figure 16

You will need to slide the steering column cover forward to cut the zip tie connection for the cruise control and turn signals located under the steering shaft (red arrow).

You can now feed the wiring harness up through the column cover and remove the switch and wiring harness from the car.
Figure 17

You can now feed the wiring harness up through the column cover and remove the switch and wiring harness from the car. Installation is the reverse of removal.





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Comments and Suggestions:
Peter Weissman Comments: Just replaced the combo switch today. Comment from left coast geek to remove the red plug connector is in fact shown in the factory manual as step # 2 after removing the negative battery terminal. I did not have to remove the engine control switch to R & R the wiring harness under the dash. There is enough room to just slide it thru. Also please note you have to slide off the cruise control stalk first before doing the same to the combo stalk to remove it from the steering column.
Good write-up overall.

August 2, 2015
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 
Left Coast Geek Comments: before removing the airbag, you should remove the red plug from the SRS control unit under the passenger foot panel. that disarms the SRS circuits completely, puts it in safe mode.
April 9, 2015
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 

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