Intermittent keyless-go operation

[Benz-O-Rama]

Gents, Recently, my 2004 E500 has started to exhibit intermittent and sporadic keyless-go starting. The doors will always lock or unlock using this feature but the button on the shifter will sometimes start the car perfectly on the first try, sometimes not at all. And sometimes, I have to push the button 3, 4, 5, 6 times and it'll start. Tried replacing the battery, but no joy. And since the doors always operate as expected, I knew a bad battery was a long shot. I searched but couldn't find anything useful. I did see something about a bad tail light switch causing keyless-go not to work, which is very strange in it's own right. Anyway, any ideas?

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[amdeutsch]

Its an alternate action switch that is located in the gearshift handle. Someone posted pics of it on here. Maybe there is an issue with some light corrosion on the contacts and/or the pins the switch plugs into.

[Benz-O-Rama]

I'll try to dig that picture up, thanks. Sounds like a new shifter knob might be in order. I'm sure that'll be cheap.

[Barry45RPM]

What does the DIC say during the Keyless Go start sequence failure? "Key Not Recognized" or nothing?

On my '04 I had intermittant failure of the start sequence... sometimes it would quick cranking in mid crank. Turned out it was a bad "Stop Switch". I believe that is the brake light switch actuated by stepping on the brake. Remember that the brake pedal must be stepped on to start. A bad switch can prohibit a start.

Try pressing down harder during a non start as a way of possibly checking for this switch not working properly. It was an easy diagnosis for the techs on my car & the part was in stock.

[Benz-O-Rama]

Originally Posted by Barry45RPM

What does the DIC say during the Keyless Go start sequence failure? "Key Not Recognized" or nothing?

On my '04 I had intermittant failure of the start sequence... sometimes it would quick cranking in mid crank. Turned out it was a bad "Stop Switch". I believe that is the brake light switch actuated by stepping on the brake. Remember that the brake pedal must be stepped on to start. A bad switch can prohibit a start.

Try pressing down harder during a non start as a way of possibly checking for this switch not working properly. It was an easy diagnosis for the techs on my car & the part was in stock.

Barry,

The MFD says nothing at all. No error messages during start failure. I haven't had it stop in mid crank either. It's almost as if the button the gear shift knob isn't being pressed hard enough. I'll try stomping the brake pedal and see what happens.

[MB211]

Try removing the shift knob, cleaning contacts and installing a little bit of dielectric (butched that spelling) grease.

Most likely the button is not sending a good signal.....Better (cheaper) to try cleaning before replacing.

[MB211]

If the stop lamp switch was the fault, the car would still turn on to position #1 and #2, just to start.

[Benz-O-Rama]

Originally Posted by MB211

Try removing the shift knob, cleaning contacts and installing a little bit of dielectric (butched that spelling) grease.

Most likely the button is not sending a good signal.....Better (cheaper) to try cleaning before replacing.

Will do.

Originally Posted by MB211

If the stop lamp switch was the fault, the car would still turn on to position #1 and #2, just to start.

This is good info. It's definitely not making it to position 1. More likely its the connection or the shifter itself. I'll monkey around with it this weekend.

Thanks!

[malahhaor]

I have 2 keys, one works perfectly fine, and the other one only opens doors/trunk, if i try to start the car, tells me key not recognized no matter how many times i push it... go figure, the key must be bad.

[Benz-O-Rama]

Update:

Problem is definitely in the button/shifter. When it's in the "I don't want to work" mode, and I wiggle the button back and forth while applying pressure, it's starts right up. Same goes when I shut it off. So, either bad shifter/button or, as someone mentioned, bad contacts. I'll pull it apart and take a looksie and see what's what.

Thanks, gents.

[DrDrilZ]

for some reason mine will sometimes not work when the key is next to my cell phone in my pocket.

[Benz-O-Rama]

Originally Posted by DrDrilZ

for some reason mine will sometimes not work when the key is next to my cell phone in my pocket.

Yep, that's normal RF interference.