[Dixyy]

I went to open my car the other day, an 03 CL500, and the key fob did not work. I replaced the batteries and it still wouldn't work.
I then tried to open the door with the metal key, but it wouldn't unlock (never tried the metal key before).

I then wondered if I got the metal key mixed up with my old CL that was written off, so I tried the key in the boot and it opened it with no problem, but the alarm went off.
Luckily, I could use the key fob to stop the alarm. I tried to open the car using the fob once again and the car indicators flashed as they should and the door opened.
The rest of the day the car opened just fine, even from some distance away.

Today, a few days later, I went out to the car and the key fob would not open the car once again, no flashing lights on the car (the key fob light would flash red).
This time I went straight to the boot and opened it with the metal key, switched the alarm off, and tried the key fob once again for it to be working as it should.

Does anyone have any idea what could be wrong?

I do have a spare key fob somewhere, but I cannot find it to see if the problem persists using it.

 

[mlupone]

I went to open my car the other day, an 03 CL500, and the key fob did not work. I replaced the batteries and it still wouldn't work.
I then tried to open the door with the metal key, but it wouldn't unlock (never tried the metal key before).

I then wondered if I got the metal key mixed up with my old CL that was written off, so I tried the key in the boot and it opened it with no problem, but the alarm went off.
Luckily, I could use the key fob to stop the alarm. I tried to open the car using the fob once again and the car indicators flashed as they should and the door opened.
The rest of the day the car opened just fine, even from some distance away.

Today, a few days later, I went out to the car and the key fob would not open the car once again, no flashing lights on the car (the key fob light would flash red).
This time I went straight to the boot and opened it with the metal key, switched the alarm off, and tried the key fob once again for it to be working as it should.

Does anyone have any idea what could be wrong?

I do have a spare key fob somewhere, but I cannot find it to see if the problem persists using it.

Did you ever figure out what was the problem? I'm having a similar issue with my 2016 G550. Thanks.

 

[Dixyy]

Did you ever figure out what was the problem? I'm having a similar issue with my 2016 G550. Thanks.

Sadly not.

A forum member thought it could be the Electronic Ignition Switch (EIS) putting something to sleep.
I then contacted themasterlocksmith.com who repairs EISs a few days before Christmas. They emailed me at 11 PM on the 21st of December to ask why I disconnected the battery and again later that night to ask "So before you swapped the wheel everything was functioning fine?" I emailed him back 3 times but he stopped replying to my emails.


I then sent my car to an independent Mercedes garage that had the car for 1 week, they faced the same problem each morning but could not find a solution. They said if they had to guess, they would suggest replacing the PSE Pump and hope that fixes the problem.

I then contacted someone called Fawad from eBay who repairs PSE Pumps (Username: germanpartz1 germanpartz1 on eBay), he was very responsive and initially thought that the circuit board in the PSE Pump may be failing and putting something to sleep, however, a few days later he said "It is a very peculiar fault you have with opening the boot then the central locking starts working. I've been repairing PSE Pumps for over 15 years and haven't come the scenario that you've mentioned." he then suggested either the EIS, overhead control panel or antennas may be to blame.

I have since ordered a PSE Pump from eBay (America) and it should arrive at the end of the month, I will then replace it and hope it solves the problem, if not, at least I will have a spare PSE Pump.

Yesterday I tried reaching out to another company that repairs EISs to see if they had come across this problem before, I asked if it could be related to a failing EIS, and they emailed me last night and asked that I plug in a diagnosis tool and send them the fault codes. I messaged them back to let them know that there are no fault codes, so this route is not looking too promising but will wait and see what they say next.

Once I get to the bottom of it, I will of course post an update.

 

[mlupone]

I'm so sorry to hear about your troubles. I take my car into the dealer later today. I'll share what I learn.

Matt

 

[Dixyy]

I'm so sorry to hear about your troubles. I take my car into the dealer later today. I'll share what I learn.

Matt

Thanks Matt, I need all the help I can get.

 

[mlupone]

The dealer diagnosed the problem as the Central Locking Antenna and wiring needs to be replaced. Apparently, there was previous water intrusion (either through poor windshield seal of wiper arm seal) that caused some corrosion. The cost of the part was under $300. Because the part requires dashboard and center console removal, the cost of the labor is $4,500.

 

[Dixyy]

Thanks for the update.

We sort of ruled out the antenna being the problem because once we manage to get into the car, the remote would work for the rest of the day but fail the next morning like clockwork.
Also, my key has RF for the antenna which is part of the rear window, it also has an Infra Red signal and both work/fail at the same time.

I have ordered a PSE Pump from America and it should arrive by the beginning of next month, I will let you know how I got on.

 

[Dixyy]

I replaced the PSE pump yesterday and the car still would not open this morning.
I have an electronic ignition switch (EIS) on order and should arrive any day, let's hope this will solve the problem.
I will keep you all updated.