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Lou P. master tech
Lou P. master tech, Mercedes Technician
Category: Mercedes
Satisfied Customers: 4583
Experience:  15 years master certified 100% fix rate and have access to factory radio codes, wiring, and instructions.
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Sl500: I have a 2005 Mercedes SL500. COMMAND screen starts

Customer Question

I have a 2005 Mercedes SL500. COMMAND screen starts up with the star and then goes black. Have looped all the fiber optic components with no change. Scan shows that there is a short in the 'Wake up line' circuit. What generates the wake up call? Pressing power on COMMAND will wake unit up- no radio, no nag (says system unavailable), no cd changer, no satellite radio. After about 30 seconds, COMMAND shuts down. Also seem to stay on after key is turned off and removed from ignition.
Submitted: 2 years ago.
Category: Mercedes
Customer: replied 2 years ago.
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Customer: replied 2 years ago.
Expert:  Lou P. master tech replied 2 years ago.
Hello my name is ***** ***** i will do my best to help you , i strive for EXCELLENT service and nothing less. So sorry for the delay. The fiber optic system is easy to diagnose , radio issues are generally software related and a software will fix 99% of audio issues. Especially when the radio turns on and off by itself. As for the wake up signal it is generated by the radio itself. Remove the fiber optic from the back of the radio , turn the radio on and see if the port that the fiber optic plugs into will flash red at you. That is the fiber optic wake up signal. The radio sends out 2 signals. 1 is electronic to all the other units on the fiber optic lines and then 2 - it will
Send a fiber optic flash to check for units available on the fiber optic lines. The wake up code is always referring to the electronic signal. Which again is commanded by the radio. So most likely you need s software update at a dealer. That is what I would do before replacing any parts. It's quick and cheap and easy. That will determine if the radio is bad or not. Hope this information helps Please take a second and click the box and rate my service GOOD OR EXCELLENT SERVICE if you feel I have been helpful and please request me in the future. If you feel I have not been helpful please DO NOT RATE BAD OR POOR AND WASTE YOUR MONEY , I will opt out to see if another expert can provide more or better assistance so you're not wasting your money!!. Thanks for choosing just answer. Lou. also , if you feel i deserve one , BONUSES are GREATLY APPRECIATED ! 😉