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Repair of a "Stuck" Smart Ignition Key

Jim & Wilma

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If you have a Smart 453, you might want to take a minute and read this - may come in handy some day.

Our 2017 Smart ignition key would not rotate to the off position and was stuck in the accessory position.  This occurred after the car sat for a couple weeks and battery voltage was too low to start.  We bought a new group 47 battery and the car is starting, holding a charge and running well but the ignition key could not be removed.  For a couple days I disconnected the battery ground to save the battery.

Today, I dug into the ignition switch assembly, first by removing the upper and lower shrouds covering the steering column.  There are two torx T20 screws holding each cover.  In the first picture below, you can see the exposed blue locking solenoid which is just below the ignition switch and also held by two T20 screws.  The black rubber cap is a dust cover on the back side of the solenoid plunger.  The material was easily pliable, sticky and "held" the solenoid plunger from operating.  I made a red replacement cap from what I think was an old air line protective boot I had.

Everything went back together easily and life is good again.

Couple side notes/thoughts:

  • Our shifter was also temporarily locked in Park.  There's a yellow release lever buried under the shifter which will unlock it.  Not sure why it locked (or wouldn't unlock) but it was definitely related to the battery low voltage problem.  Others have had this issue too.
  • I suspect the solenoid's black rubber boot was a problem waiting to happen and was pushed over the edge by the weak battery.  I'm guessing the low voltage caused an increase in current with resulting increase in IxR heating of the solenoid coil and further softening of the black boot.
  • The Smart battery is NOT a common size and nearest battery was a couple hundred miles away or a few days by mail.  The group 47 battery (flooded lead acid, not AGM) is very close to the same size.  A feature of the Smart's Italian made battery is it has a vent port which attaches to a tube that runs to the battery tray.  I guess this keep any venting electrolyte gas/liquid from collecting on the battery top and accelerating terminal corrosion.  Nice but not necessary, in my opinion.





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  • 11 months later...
  • 3 weeks later...
5 minutes ago, Hewhoknowslittle said:

When mine failed I completely removed it. 
This will never happen to me again. 
No codes or lights on on the dash. 

Yep, if ours had failed, I’d have done the same and not thought twice. Somehow we drove cars in the old days without all the automatic “features” and survived.  Not sure why the key removal lock “feature” even exists; suppose it’s to make sure transmission is in Park. I suspect you’ll be ok young man.

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  • 2 weeks later...

I have a different problem, of my own making, I have misplaced my only key for my 2008 Smart. I loaded it on the flatbed and then drove a different truck to our new home in Arizona, from Vermont.  I thought I left the key in one of the 3 vehicles in Vermont but now I cant find it! Any way to do away with the stupid chip key and just put in a different switch I may have to lift the car off the trailer next week when I get it to Arizona because I need the trailer.

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  • 8 months later...
  • 2 weeks later...

Well, it seems with our maiden trip to the WCR completed and our confidence increasing, we are in the hunt for a Smart(driving the Volvo to Walmart isnt the fun I prefer, although very doable).  Found a nice low mileage 453(not easily done right now) and so ready to order some ramps in anticipation.  I have found the more popular are Discount Ramps 12'L X 12"W folding ramps.  Now to determine the better approach to tying it down.  We will have alloy wheels so not sure if baskets or through straps are better.  Any opinions out there?  I will be making my own chocks to add the ratchets to.

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5 hours ago, GeorgiaHybrid said:

I use over the wheel straps. The baskets can give you issues with the brake lines, and I have never liked putting straps thru the wheel. There is too much of a probability that the straps will rub the finish on the wheel.

Same here.  Did the "through the wheel" thing for a while and often the wheel would turn just a bit and loosen the strap.  Since going over the tire with a single strap, we've never had a strap loosen.

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Here's an example.  https://www.uscargocontrol.com/products/car-carrier-strap-w-wire-hooks-adj-rubber-blocks-ratchet

I used separate straps and ratchets, mounting the ratchet to the bed, and storing the straps in the tool box when not in use.  The rubber blocks make the strap quite secure.  In fact, I'm making up a similar arrangement for the wife's Spyder.

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Thank you so much for this post! I was able to remove the solenoid at work so I could power down my 2017 Smart EV so that I had enough range to make it home since it was draining my high voltage battery fast. Wasn't able to find a new battery anywhere except for Mercedes. The solenoid was red hot and completely failed after installing the new battery so I removed it.

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I used Mac's Custom Tie Downs.


I got 2"X 7' straps...didn't need 10' for the Smart. Also got the twisted S hook on the one end. Call them and tell them what length you want. Single strap with 3 rubber blocks using their lashing winches. If you get the lashing winches like we did you need to specify right and left. They recommend one foot of strap to wrap on the winch. They had a pretty long lead time when we ordered. If you're willing to pay for expedited shipping you go to the front of the line. They are great guys and have nice stuff. I believe Georgia Hybrid uses the same ones.

Edited by unimog1300
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