Q: My 2005 MBZ SL500's dimming rear view mirror stays dark in daylight unless I turn on the adjacent overhead light.

asked by on November 01, 2017

My 2005 MBZ SL500's auto-dimming rear view mirror stays dim (dark) in daylight unless I turn on the adjacent overhead light. With the light on somehow the mirror knows to go to daylight mode. The dim is fine at night and doesn't go to daylight mode. Is there an easy fix to this?

J. Curtis jcurtis595@gmail.com

My car has 52000 miles.
My car has an automatic transmission.

Electrical components are not working Inspection $94.99 - $114.99 Get a Quote

What you are describing is likely a consequence of a failure of the ambient light sensor on the forward facing part of the mirror, although check to be sure that the light sensor is not somehow "blocked". The sensor is usually integral to the mirror assembly and so the mirror assembly would have to be replaced in that event. Hypertechnically, the sensor could be replaced by an electronics technician, who is skilled at board level work, and that might be an option for you if Mercedes Benz either charges an exorbitant amount for a new assembly or the new assembly is no longer vended. If you would like a certified mechanic to diagnose this issue and get a repair, or replacement, implemented (btw, used copies of the mirror are available, if MB does not vend the part), please request an electrical components diagnostic. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing


Experienced Mechanic?

Earn up to $70/hr

What others are asking

Paint bubbles and rust on new car
I have seen this issue on several Equinox’s, most commonly on the back tailgate, around the edge of the door panels and under the front doors. Unfortunately, GM has issued no recalls or Technical Service Bulletins(TSB) to address this issue...
How do I use the remote start?
If the vehicle is equipped with the remote start option, then the keyless entry system remote will have 4 buttons. The button at the top will have a curved arrow on it. Press the “lock” button before pressing the remote...
The car is misfiring.
Hi, thanks for writing in. There are many things that could cause a misfire (https://www.yourmechanic.com/article/how-can-problems-with-the-ignition-system-cause-misfiring_2), such as faulty spark plugs (https://www.yourmechanic.com/article/symptoms-of-bad-or-failing-spark-plugs), a bad coil pack (https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-ignition-coil), bad injectors (https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-fuel-injector), a faulty crank position sensor (https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-crankshaft-position-sensor) or something else. I would...
Screeching and howling noise under the hood
Hi there. The serpentine belt (https://www.yourmechanic.com/services/serpentine-drive-belt-replacement) rides on a variety of pulleys (https://www.yourmechanic.com/services/idler-pulley-replacement), as well as the tensioner. Each of these "rotating elements" has a grease filled bearing, typically ball bearings. Over time, the high heat of the engine causes...
The heater doesn't work, defrost works a little, fan doesn't turn on?
Hi there. The blower fan switch not working may be, a blown blower motor fuse (https://www.yourmechanic.com/services/fuse-replacement), a faulty blower motor relay (https://www.yourmechanic.com/services/blower-motor-relay-replacement), a faulty blower resistor (https://www.yourmechanic.com/services/heater-blower-motor-resistor-replacement), a faulty blower motor (https://www.yourmechanic.com/services/heater-blower-motor-replacement), and/or a faulty blower motor switch (https://www.yourmechanic.com/services/blower-motor-switch-replacement). Proper...
Low fuel pressure at the fuel rail (30psi) then drops to 10psi occasionally while idling. The fuel sending unit was just replaced. 2004 Dodge Dakota
Hi there - yes, you clearly have a fuel supply issue, mainly focused on getting enough pressure in the fuel rail to the injectors (https://www.yourmechanic.com/question/fuel-pressure-drops-after-30-mins-of-driving-by-sarvan-s). Check problem codes first, even if the Check Engine light is not illuminated. I suspect...
OIL ON SPARK PLUGS
Oil can leak into the combustion chamber from either the piston rings or through the valve guides (past the valve stem oil seals). Of course once oil is there, the spark plug can get contaminated. If the leak is past...
I have an 08 lexus rx350, i hear a clunking at low speed on uneven road. I checked the rear wheel by shaking and I feel some free
What you are describing sounds like a failing CV joint (https://www.yourmechanic.com/services/axle-cv-shaft-assembly-replacement). A CV (Constant Velocity) joint is a shaft that connects the transmission to the wheels, essentially transferring the power from the drive train directly to the wheels. The CV...
Random low then high idle jumps
This may be a sign of a faulty MAP sensor as the vehicle responds adversely to a load put on the motor (i.e. putting it in gear, making turns (which makes use of the power steering pressure switch) turning on...

Related articles

2007 Nissan Versa vs. 2007 Saturn Ion: Which One Should I Buy?
Compact cars as a class are generally meant to be commuter vehicles: with excellent gas mileage, an entry-level price point, and decent safety ratings for those who are on the road the majority of their time. These cars also make...
Mercedes-Benz Certified Pre-Owned (CPO) Car Program
Shopping Shopping for a used Mercedes-Benz vehicle often leads many drivers to consider certified pre-owned options. Mercedes-Benz is one of many manufacturers that have a certified pre-owned (CPO) program. Each car manufacturer structures their CPO program differently; read on to...
Industry News for Automotive Techs: October 22-28
Japanese automakers step up security, Mercedes' X-Class pickup, carsharing with Turo, VW TDI settlement approved, Faraday Future behind on payments.