darin'ssl550

I have a 2007 SL550 with just under 80,000 miles. The keyless entry failed so I naturally thought it was the FOB batteries. No such luck. The Keys infrared will open the lock at very close range, but not without several attempts and the passenger door seems a bit more responsive. Trunk is not responsive and Keyless Start does not work. I have been told to replace the door handles (not cheap) as a first step. My question is, if that doesn't work, did I just waste a lot of money on door handles? Is there not a way to diagnose the problem or is it step by step each getting more expensive before we figure it out? Can I get away with just replacing the driver side door? Thank you in advance for any helpful ideas.

Rudeney

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Have you replaced the batteries in the fob? Also, do you have a second key and how does it function?

darin'ssl550

Hi Rodney, thank you for responding. The batteries are good and my second FOB works the same. The Infrared will work at close proximity but the push button on both handles does not.

Rudeney

Check fuse 58 on the rear panel. That powers the KeylessGo control unit. It sounds like RCL is also not working since you have to aim the fob at the IR sensors. In that case, also check fuse 57 as it powers the antenna amplifier system. If those are all good, then I'm at a loss. I might say that RCL has lost its sync with your keys, but since the IR interface works, that would not be the case.

dre85

Not trying to steal your thread but hoping we can all get answers to similar issues. My keyless go works occasionally under very close range and so does keyless entry only sometimes on very close range. The buttons on the doors do not seem to work. I have replaced both key fob battery's and the car batteries have plenty of power. I haven't checked fuse 57 and 58 yet, but if they were blown I would assume the system wouldn't work at all not just sometimes?

Rudeney

Just to make sure we are all using the correct terms...KeylessGo is the function where the SmartKey just need to be in proximity and can be left in a purse pocket and you use the sensors and buttons on the door handles, trunk and shifter to open, lock, start and stop. RCL (Remote Central Locking) is where you use the buttons on the SmartKey to lock, unlock and open the trunk.

KeylessGo requires the Smarkey to be in very close proximity to the car, within about 2 feet and also in certain locations where the antennas are located, which are the doors and trunk lid. RCL can work further away in a radius around the car. With a strong battery in the SmartKey and a clear path for the RF signals to reach the car, and no other RF interference, it could work 100 feet away or more. Most of the time, it works within about 50 feet or less.

The components that RCL and KeylessGo use are totally separate. The circuitry in the SmartKey is different for the two systems, and their antennas and control modules are separate. One should work even if the other does not. Note that they both use RF signals, so if there is strong interference in the area, it can disrupt on or both systems. If you find you have problems in one location, say your office parking lot, try it elsewhere and you may find it works.

KeylessGo uses several antennas. There is one in each door, one in the trunk, and one in the rear cabin panel, between the speakers. Using these, the KeylessGo system can triangulate the position of the key. This keeps you from being able to lock the key in the car or trunk. The RCL antenna is embedded in the front windshield.

dre85

Yes, the RCL works only sometimes for me. I have not had luck with the buttons on the handles to lock unlock or the push to start, push to start only works occasionally as well.

Rudeney

Here is a quick test you can perform to check KeylessGo operation. Place the keys at least 10 feet away from the vehicle. Press the lock button on the door handle and observe the MFD on the instrument cluster. If you get a message stating "key not detected", then the button is working. You may need to press it two or three times to get the message. Perform the same test with both door handles and the Start/Stop button. Lock the car, place the keys at least 10ft away, and try gasping both door handles and the trunk handle to test the unlock function. If you are getting no messages on the MFD on some of these functions, then you may have bad sensors in the handles or defective buttons. If you get no messages at all, then you may have a bad KeylessGo module. If you do get the messages, then repeat the tests with one of the keys in your hand. If it's detected in some places and not others, you may have a bad KeylessGo Antenna.

Note that with SDS (MBZ's Star Diagnosis) the KeylessGo system can be checked for error codes and fully tested.

darin'ssl550

Thanks again Rodney...I'll check the fuses as everything else will just be expensive. By the way, the push to start on the gear shift does not function and that's why I asked if changing handles doesn't work, have I wasted money? Or, are they somehow possibly connected?

gaazmon

Regarding the push start on the gear shift, try holding the shift level to the right side before coming down towards the reverse gear (so just tilt and hold it to the right) then press the start button see if anything happens. My CLK has become like this now. I thought the button was broken but my mechanic tried this and it works.

Rudeney

The Start/Stop button on the shifter is a simple circuit that is directly tied to the EIS, although it does go through the shifter module. I seem to recall hearing some forum members having issues with the wire getting pinched or abraded in the shifter module itself, hence the need to hold the knob to the right or left.

darin'ssl550

Thank you again Rodney...does that mean the Start Stop on the shifter not working, is not related at all to the keyless entry at all?

gaazmon

Yup my indy told me the exact same thing that the wire must be having an issue.

Rudeney

Locking and unlocking via the door handle sensor and button using the KeylessGo feature is related to the start/stop button in that they both use the same RFID communication with the SmartKey and antennas to do that. The RCL function using the button on the SmartKey fob are unrelated to KeylessGo.