Ronnyboy342

Transmission clunking

25 posts in this topic

I just bought a 2006 fortwo Cdi and wondering why it makes a clunking sound as if it's shifting gears before displaying neutral 

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Clutch actuator makes a clunking sound. Just listen to mine by watching below video. 

 

 

The video shows operation of my Smart Model 450 Cabrio Cdi clutch actuator.  I am engaging forward gear first followed by reverse - reverse alarm is then audible. Then I switch engine off and operate clutch actuator with ignition on by moving gear shift repeatedly into forward followed by reverse.  Both clutch actuator and trust bearing guide tube were liberally lubed with Comma PTFE Spray prior to recording above video.

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Mine does this clunking like it's changing gears or maybe checking it's gears  as soon as I turn the key on it will sometimes display 6 then maybe R then show N then the clunking stops and I can start it it seems like it's shifting up through it gears then back down to neutral 

Edited by Ronnyboy342

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But it doesn't do it every time I try to start it just most of the time 

Edited by Ronnyboy342

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I recommend you spend time under your Smart inspecting transmission wiring harness for proper clamping and possible chafing of wires.  Takes only seconds if done by a trained eye.

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I think your right Tolson today was the first time I got the three bars and the clutch is cycling in and out and the rear wiper comes on without the switch on . I scanned it and it came up with a transmission code . The brake triangle was lit this morning but has since went out . So what do I expect to find in the wiring chuffed wires shorting on the bell housing?

Edited by Ronnyboy342

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Rear wiper being on makes me suspect SAM damage too....

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Ok I know I am green as he'll when it comes to diagnosing a problem but I see no chafed wires however I have a plug that goes into the bell housing that kinda concerns me . It looked a casing from a price of shielded wire that you would use in a comercial building running into the bell housing and some sort of retainer that bolts onto the corner base p an bolt holding it into place I don't want to attempt to remove this until I am sure what it is.  I am assuming someone put the shielding off of comercial wiring over the wire to protect it but what plugs into the bottom of the bell housing ? 

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Ok with some member guidance and help I am starting to figure out the csc site and how to navigate it somewhat better but the problem I have remains with the random shifting when I turn the key on code p0702 transmission problem I have checked the wiring a very good mechanic has tested and checked the wiring and it still takes a tantrum when I turn the key on indicating 6 then R then finally neutral.  I am stumped and all I can think of is angle sensor . Any help from someone who has ha this problem is greatly appreciated

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Ok battery is at 12.6  key on 12.2. Post start after alternator has kicked in 14.1 so I suspect this sounds pretty normal

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As for the angle sensor I am going to pull that off again and test it it was super clean like your spare but I didn't know how to test it so that will be next step. I talked at great length with a mb mechanic today that suggested I remove the Sam and clean it because it doesn't seem to click through the gears until the interior has started to thaw and he suspects water in the sam? Every post I have read thus far has indicated this problem to not being Sam related but I guess it wouldn't hurt to see its condition. And another thing that needs a dressing is the fact that the temp is showing in ferenheit and the fuel countdown is not working and if I understand correctly.from other posts that is because the battery went dead last winter for an extended period could this be so?

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On 10/02/2017 at 6:20 PM, Ronnyboy342 said:

 

Correct I am give or take a few mins off of 3 hours from the tec he is in Halifax.  The weather has been all over the map here and it's been tough working on the smart because of.the weather but I have a really good mechanic and he has let me use his shop to replace the alternator after the top bolt fell out and jumped around until it snapped the charge cable.  So now I have a new cable new alternator and all new belts. Just getting frustrated by this clicking of the transmission ghost shifting before it will allow me to start it

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Ok check check and check shifted to N then to 1 then to N then to reverse then to N then to 1 followed by 2 then to N  the transmission showed shifting from 2 then to 1 then to N and I could hear it shift down . So your saying its most likely not a wet Sam if I understand correctly ? Any idea what to try next ? I have been trying to get a used angle sensor but haven't yet done so . The weather has been miserable so I haven't got mine off again yet but when it was off all of the contacts were shiney where visible and the plug was super clean . It runs and shifts good and I have only had 2 incidences of 3 bars and that was after shutting it off in reverse  if I shut it down in neutral it just clicks through the gears then finds Neutral then off we go. Shifts smooth engages good auto shift works all I really notice is a momentary dimming of the dash when I apply the brakes I assume this is because of the lights being activated and the actuator pulling in the clutch maybe??

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Yup once it establishes n it starts like a champ drives equally well . It doesn't seem to effect it besides being annoying . But I know something happened at some point because fuel countdown is gone and it's reading ferenheit for the temp . I am just guessing here but seems it's lost it sam programming ???

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I always check out transmission wiring harness using test lamp and ammeter. 

SmartTM_Wiring.jpg

Left column is pin in main ECU connector plug.  Right column is corresponding pin at actuator or sensor.  When checking out wiring harness, I disconnect all connector plugs and lay out harness on top of engine.  I use a 21 Watt test lamp, a 12 Volt battery, a multimeter set to measure current and various suitable cables and pins.  I then inject current trough the harness from ECU pin to actuator/ sensor pin.  Any fault will show up as low intensity light out of test lamp and low current.

Purely testing from pin to pin with multimeter I have found may not be sufficient to identify faults as a cable with all strands broken but a single one will test out fine.

Edited by tolsen

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Ok I guess I have hit the wall I pulled the harness again and checked the wiring again by supplying power from the main plug to each sensor plug and every one carried steady voltage . I also noticed when I used the code reader in the drop down from the po702 code there was a sub code of c1330 again some posts have pointed to brake light switch but that seems to be functioning as usual . Another post referred to input speed sensor I am totally lost in searching for that one is that the same as rpm sensor because that appears to be looking for engine rpm as per its positioning or am I missing something 

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I did this by supplying 12.5 volts to a headlight through the wires of the harness from the ecu I am sure very similar to what you described and if these wires will light a sealed beam headlamp to full brightness they can't be broken 

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Do you not think that a sealed beam headlight 55 watts is sufficient current draw to test the wires from the ecu to the sensors???

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Pretty sure I have run up against a problem here that is going to require the 3 hour drive to access to a star machine and paying to find out which sensor may be faulty or have faulty.wiring . I have run current through the harness to a very heavy drawing sealed beam head lamp and it lit on every wire that I was able to access from the ecm plug to its sensors  I have done all I know to do thanks Tolson for all your help and suggestions however I can't fix wiring that is able to carry a 55 watt load . Cadillac man thank you also but I think I need to spend 6 hours of driving on this issue hopefully euroworks can isolate the sensor causing this error . 

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Seems you are right on another point @cadillacman the sam has no water damage it doesn't seem to ever even get dust inside let alone water it's clean as clean can be so thanks for the test procedure but I needed to see for myself as for the area that it could leak it's plain to see if there was condensation it would defiantly drip on the sam because I can see right up to the windshield and side window through the dash

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Wondering if this ever got fixed?

 

    Having the same issue...  also saw a 6 then down arrow and eventually N  But I cant get R.   Was it in fact wiring?

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