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Discussion Starter #1
I've got a 2008 451 pure, 47000 miles. The car tends to lose it's sense of what gear it's in at various times (sometimes when at a stoplight, sometimes while moving through the gears on local streets, and once while cruising on the interstate). Then it gets all confused and various warnings appear: the check engine light appears and flashes, the double wrenches appear and flash, the big D (Drive) switches from solid to flashing, and the yellow exclamation triangle appears and flashes. It also then goes to and stays in 5th gear. After slowly moving to a safe place, I turn off the engine and the 3 horiz bars show. In order to get the car to start, I then go through the sequence of waiting about 30 secs to a minute, then put foot on brake pedal, turn ignition key to position 1, then shifting from P to R, N, D and back for the electronics to figure out where it is. Once I see the D re-appear, I can go to P and start the car. The wrenches disappear, sometimes the check engine and the safety exclamation lights disappear too!

This has now happened more than 6 times in the past 2 weeks. Last Sunday (6 days ago) I removed, cleaned and adjusted the clutch actuator, using the advise found in threads on this forum. I found the insides of the actuator with powdery, dried out black lubricant, and relubed with white lithium grease. I reattached the actuator to the spec sheets recommendation of 3 gradation lines displacement from abutment towards the bell housing. I don't believe the actuator is the cause of the problem, since the shifting confusion has occurred before and since the cleaning. The worst was yesterday, it ran amok 4 times in 4 miles before I could get it home

Any ideas would be appreciated. Today I put a help request to the local smart center using their web-link in smartusa, but I have never dealt with the service center, having bought this car used.
They phoned me almost immediately, wanted to know if I wanted to set up an appointment.
Being on a very, very limited budget, I cannot blithely setup a service appt and hope for the best to a Mercedes Benz service dealership. I need some reassurances before handing over the keys. I asked to speak to a service tech, was told all were busy so my message would be passed on to them and one would get back to me.

So has anyone here had a similar problem with their car, and how did you fix it?
 

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Discussion Starter #5
I replaced the battery, cleaned up all connections there and found to my dismay the car is even worse now than before - it errors out with the 3 bars of death going from 1st to 2nd as soon as I drive it. The new battery is fine, 13.78 volts (the smart orig battery was probably fine too, at 12.6v, but I replaced it anyhow)
 

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A good battery wont make the problem worse, but a wiggled loose connection would. I'd still say bad ground since it got worse by moving the wires around down there. See if anything attaching to the chassis is loose(loosen and retighten too while youre in there, 10mm socket). If not, consider replacing the main ground lead with a generic 2 or 4 gauge 10" ground cable from autozone.
 

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A good battery wont make the problem worse, but a wiggled loose connection would. I'd still say bad ground since it got worse by moving the wires around down there. See if anything attaching to the chassis is loose(loosen and retighten too while youre in there, 10mm socket). If not, consider replacing the main ground lead with a generic 2 or 4 gauge 10" ground cable from autozone.
I would also go 1 step farther and pull apart all the connections you can get to and reconnect with some dielectric grease :)
 

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In my case

was the shifter motor oil from the transmission went inside the carbons try to pull the 2 covers of the shifter motor and clean first with gasoline and then another cleaner like break cleaner.
 

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Discussion Starter #9
I am planning to attack this possible electrical shorting issue tomorrow. Does anyone here know of any similar threads on this forum where this problem has been discovered and hopefully resolved? I HAVE noticed the headlights wavered slightly in intensity from time to time, but always seemed so slight to might be just my imagination, but now...hmmmm.
 

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Discussion Starter #10
was the shifter motor oil from the transmission went inside the carbons try to pull the 2 covers of the shifter motor and clean first with gasoline and then another cleaner like break cleaner.

Uhh, you lost me there, rubyg. Could you explain what you mean? Meanwhile I'll poke around down there.

Also I went through every ground bolt, fuse, and connections I could find around the battery. There is no sign of corrosion, every connector was tight, no resistance found by wiggling the wires all over. I doubt the issue is in the wires around the battery.
 

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The shifter motor is located on top of the transmission is actually 2 motors in one with some hall sensors if you take the air intake from the air filter boc to the engine you can have access to the motor it has 2 connectors.
You can remove the left and right cover of the shifter motor and clean with a brush and some cleaner,carfully inside each cover there is a magnet dont drop them they can crack.
In my case I paid $1000 for a new motor at the dealer, I took the old cleaned and compaired with some friernd spare and check it with a power supply in both direcctions of rotation and perform the amps comparation and they were the same.
A month later saw the service manager in a shopping center and I ask him why he didnt clean this part the response was we at the dealer we only change parts we dont try to clean o fix nothing...
 

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Discussion Starter #12
Problem is fixed, thankyou all for the advice.

Finally had time to install a new neg terminal post and heavier gauge cable to ground. Also got some dielectric grease, and went back carefully re-cleaned and greased all positive and negative connections within the battery compartment, as well as the blades to the 50 amp fuse found near the positive post connection.

Total cost: $10.61. Drove it this afternoon and evening for about 20-30 miles without a hiccup in the shifting.

WOW! :thanks_smile::thanks_smile::thanks_smile: to all for the GREAT ADVICE!

Amazing how sensitive the electronics must be to have such a simple fix for what appeared to be a major FAIL in the vehicle. I hope the newer models have addressed this issue.
 

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The shifter motor is located on top of the transmission is actually 2 motors in one with some hall sensors if you take the air intake from the air filter boc to the engine you can have access to the motor it has 2 connectors.
You can remove the left and right cover of the shifter motor and clean with a brush and some cleaner,carfully inside each cover there is a magnet dont drop them they can crack.
In my case I paid $1000 for a new motor at the dealer, I took the old cleaned and compaired with some friernd spare and check it with a power supply in both direcctions of rotation and perform the amps comparation and they were the same.
A month later saw the service manager in a shopping center and I ask him why he didnt clean this part the response was we at the dealer we only change parts we dont try to clean o fix nothing...


GFY
 

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Discussion Starter #14
Whoa STOP! Problem is NOT fixed, need more advice.

The shifting issue has returned. For the last two weeks the car would lose sense of what gear it's in about once every other day, on the the return trip of a 44 mile commute. No biggie, I'd just pull over and park, turn off engine and go thru the restart routine as mentioned previously.

Today it happened 3 times in a 4 miles. I was on secondary streets. Once I was finally able to get up and running smoothly, I stopped at a Autozone, the code is P0707:Transmission Range Sensor Circuit Low Input

Could this be one of the hall sensors in the shifter motor that rubyg wrote about?

At one of the failures, I noticed I had a choice of 2nd or 4th gear when in manual mode. The other time it was 5th gear only.
 

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Discussion Starter #16
Removing the air-filter-to-engine plastic pipe assembly (ugh, that lower right screw was a ***** to remove!) exposes the shifter motor on top of the tranny. Noted the shifter motor breather port with cap has appeared to leak oil over time. (Maybe the tranny fluid has been expanding too much or foaming?)

After cleaning the exterior a bit, noticed the multiple screws holding the motor covers in place. Will probably attempt to open them after cleaning the exterior more and tucking shop rags under the unit to catch the internal magnets (if they fall) rubyg has cautioned about.

smarticus, did you have the same code too?
 

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My Ultraguage is not showing any code. Odd I think that it wouldn't. My dash shows the double wrenches from hell -2. I first will service and reset the computer and see if that helps. Then I will start looking for loose connections and fittings.
Surely the magnets are not just floating around loose under the covers,...it seems like they would be attached some way. ( Maybe that's the problem, bad glue ) Mine has done this about 6 times in the past week or two, including yesterday afternoon and just about 20 minutes ago. It's really getting old, fast. I just put new wheels, tires and a nice Carlsson exhaust on and it would be nice to be able to enjoy them. The problem was there before either of the changes / improvements were installed, so they aren't the problem.
I will post any findings.
 

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Discussion Starter #19
As of yesterday I have finished cleaning out the electric transmission motors and replaced the gearbox oil with Redline MT90. The 2 electric motors were infused with a mixture of oil and carbon, about an ounce of the gunk was flushed out of the right side motor. After flushing the motors with electrical parts cleaner, I lightly greased the motor bearings with dielectric grease in hopes of creating a barrier against further tranny oil invasion (or at least slowing it down). Added the Redline before replacing the motors, just poured it in through the mounting hole until it came out the upper fill hole. I took pictures of everything I could think of during the process. I also cleaned the connectors and lightly greased the seals to both motors upon reassembly. Looking up at the motors from underneath the car, I realized these cable connectors are very much exposed to the elements. Also saw that the tranny oil had seeped over time enough to lightly gunk up the drive shafts to the rear wheels, so I cleaned that off with brake cleaner as well. The old tranny oil was a dirty chocolate brown, with gold highlights when swirled, showing the brass wear, I guess. Total cost: $76.70. So far I have driven the car just over 100 miles with no check engine light, other than one showing when I first started it up. That was expected, since I had disconnected the battery and the computer had to find just where everything was. Also had the ESP warning exclamation show until I turned the car off and restarted, also expected. Keeping my fingers crossed at this point...
 

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Hey, I had the same problem. Sometimes it would shift before or not even shift when going up a hill. I had that problem until one day my smart just decided to jump 3rd gear all together. I turned off the car, turned it back on and the problem disapeared. Took it to the dealership and all they did was install the 2012 hardware. Problem was solved...
 
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