WIS 82.25 Signalling Equipment/Emergency Alarm System

External Mirror Turn Signal

Issue

Applying a turn signal produces an error code such as "check the right turn indicator globe" and fast (double frequency) flashing of the dashboard light. The external turn indicators still flash at the correct frequency.

The issue may only happen occasionally and resets when the ignition is turned off, although the ECU stores a fault.

It can be very frustrating especially when you check all the turn indicator globes and they appear all OK.

• A common issue with the External Mirror Turn Signal LEDs is a broken wire where the wires flex when the mirror folds.
• One or all of the LEDs work intermittently caused by bad connections on the LED printed circuit boards.
• The LEDs in an external mirror may be glowing dimly.
• The problem can be, but is most likely NOT, the passenger side door control module (DCM) which controls the seat heater, seat controls, window and mirrors.

Solution for Broken Wires

• Remove the mirror by pressing in a small spring clip at the top.
• Release the mirror housing cover by also pressing in a spring clip near the outer edge.
• Unclip the LED unit from the housing.
• Plug the LED unit into the connector.
• Turn the emergency flashers on (no need for the ignition switch to be on).
• Test by carefully pulling and pushing the thin, identical black wires where they bend when the mirror folds until you find a faulty wire.
• Usually they break inside the insulation, which is not visible.
• It may also be inside the mirror structure where a splice is not possible.
• Remove the insulation at the break.
• Splice in an additional two-inch piece of wire which should allow you to pull the broken ends out of the structure
• Complete the repair by splicing together each broken end.
• Take the time to very carefully seal the seams on the LED unit with clear RTV silicone, which helps prevent water getting into the unit.
• Reinstall

Problem solved - less than an hour and no cost.

• With thanks to wallyp at reference: http://www.benzworld.org/forums/w220-s-class/1707657-s500-w220-mirror-turn-signal-issues.html

Solution for Faulty LEDs or LED Joints

• Remove the mirror by pressing in a small spring clip at the top.
• Release the mirror housing cover by also pressing in a spring clip near the outer edge.
• Unclip the LED unit from the housing.
• Test the individual LEDs on the bench with a suitable power supply.
• The OEM LED joints are crimped.
• Resolder all the LED joints.
• If any LEDs are faulty they can be replaced individually.
• Factory LEDs are 4.5W.
• Typical replacements are 5W but don’t have enough resistance.
• Solder three 33ohm, 1/2 W resistors from Radio Shack, in to the wiring.
• Clean and lubricate all the connectors with rubber grease (helps prevent water ingress).
• Put rubber grease on the seals.
• Reinstall