Gearbox/Starting Problems - Need ideas!

[Elboor]

Hello all!

Having trouble with a newly acquired Smart (Pulse Soft Tip Semi Auto 599cc) - I bought the car with problems and decided to undertake the repairs myself - although I have been successful just a bit stumped as what to try next. Never owned a Smart or even driven one so everything is new to me but overall I think in not far off just need some more input/ideas.

Ok so heres the timeline:

Previous owner mentioned car had been sat in storage and battery died, Recharged battery and 3 lines appeared on dash.
Unable to start car/select gear.

Bought car - got it home and began looking online for common faults/problems. Checked wires/gear position sensor/gear select motor/clutch actuator.
All looked OK and seemed to test OK on multimeter.

Ripped both seats out to further trace wires and came across a box (Engine electrical centre) under pass seat. Found corroded wires/snapped pins from water damage!
Replacement Engine Electrical Centre fitted - success!! Can get the car to start and run (wheels in air) and can go up and down the gears.

However I can only get the car to display N on the dash (to allow me to start it etc) if I do one of the following:

(1) Disconnect the battery for a few seconds and reconnect (Car then primes fuel pump, lots of noises, clutch actuator and gear selector sound like they're moving) and the dash will display N and I can start the car and operate it as per normal.

(2) Or I disconnect the plug to the clutch actutator itself and the car will display N on the dash and allow me to start (obviously wont let me change gear etc but will start).


If I do step 1 the car behaves fine until I turn it off and try to restart it. It will then display N in the dash but it will flash N and not stay on, at the same time the clutch actuator starts moving back and forth slightly as if its trying to locate home? and will keep moving back and forth until I turn the key off or disconnect the battery.

Again I disconnect battery (10 secs) turn key, N displays (solid) start car, can go up and down 1-6 and R no problem.


Anyone have any idea? I get the impression that either the clutch actuator is trying to relocate a home spot or that it isn't aware I've turned the car off and it still thinks its running/on? Stuck relay? A broken wire elsewhere? Clutch actutator worn out?


Any ideas would be great! Thank you!

[tolsen]

Could be wiring or just stiff clutch actuator. Wiring tends to suffer wear in way of contact with inter cooler cradle and at end of protective sleeve just before plug that connect to clutch actuator.

Below is a video showing 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 video. Beware do not overdo lubing. Could contaminate both clutch and brush gear on clutch actuator motor.

Gear position sensor may suffer damage due to water ingress. Worth while to remove, clean seal area and refit with suitable grease on seal area.

[Elboor]

See this is the strange part about it! I can get the clutch actutator to operate correctly but it refuses to continue working correctly the moment I turn the car off and back on again. This cannot be down to wires alone surely?

Disconnect/reconnect battery -> Turn key one click -> N is display (solid - no flashing) -> Start car -> Gears work, car runs, everything good -> Turn car off. -> Turn key one click -> N is displayed (but now flashing) -> Attempt start - nothing.

What does N flashing mean? And why does the clutch actutator start misbehaving after N begins to flash?

[tolsen]

What age or registration year is your Smart?
i have seen flashing N on my 2002 Cabrio but can't remember just now what was the cause.
Can you read fault ccodes? Can be read up here for the equivalent cost of a pint of good ale.

[mottofreee]

Three bars = faulty gearbox.
Water/corrosion/ in (2) or component (1) damage (jammed).http://www.fq101.co.uk/how-to-guides...x-sensors.html .
You greased clutch actuator? (important)
The multimeter is insufficient in this case. Diagnozer is required - only Star C3 / C4 or Winstar. Just these designs show everything to Smart.

[heinkeljb]

It probably needs the gearbox "re-teach" / "clutch adjustment" via the ECU. This can be done using the MB STAR or WINSTAR mentioned above.

John

[Elboor]

2002 Year - Pulse Soft Tip Semi Auto. 599cc.

Have no access to Mercedes spec diagnostics. Anyone here in the area of Hampshire/Wiltshire?

I'm going to recheck some wires again today, specifically the ones that attach to the clutch actuator that return the ECU - I get the impression that the clutch actuator doesn't need to know its start up position when I've completly disconnected the battery and works because of this. So perhaps there is an issue with the wires that tell it where it should be because it won't stop moving after its been started once?

Pin 1 = Green (0.5mm2) = Negative supply to actuator feedback system. Connects to Pin 43 on ECU Connector 2.
Pin 2 = Yellow (0.5mm2) = Position signal return. Connects to Pin 24 on ECU Connector 2.
Pin 3 = Yellow (1.5mm2) = Motor power supply (plus). Connects to Pin 4 on ECU Connector 2.
Pin 4 = Yellow (0.5mm2) = Position signal return. Connects to Pin 23 on ECU Connector 2.
Pin 5 = Blue (0.5mm2) = 5V supply to clutch actuator electronic feedback system.
Pin 6 = Yellow (1.5mm2) = Motor power supply (minus). Connects to Pin 5 on ECU Connector 2.


I just find it strange how it all works ok if I completly kill all power to the vehicle and restart, but clutch actuator starts screwing about if I leave battery connected and just try to restart car!!

[lalli_d1]

i think you are pissing in the wind, so to speak.

you NEED to get the car on mercedes diagnostic machine and see what codes are logged. a multi meter is no good on 'modern' cars without you knowing where to look.

have the car recovered to a mercedes dealer or a smart independant and get a diagnostic read.

Smart stuff is in somerset.

[tolsen]

Can be done without diagnostics if you can get wiring and all components to work. Diagnostics would however make it easier to home in on the faults. Electronic adjustment of clutch actuator is not critical.
Suggest you check wiring between clutch actuator and ECU by using a minimum 55 watt bulb as test lamp. The thin cables are usually the culprits. Get good electro tape, self amalgamating tape and heat shrink sleeves. You also need hydrochloric acid, solder, flux and solder iron.

[mac999]

Have no access to Mercedes spec diagnostics. Anyone here in the area of Hampshire/Wiltshire?

I am located in Swindon and could come carryout the diagnostics for you

[tolsen]

Just measuring continuity of wiring with a multimeter is not good enough. A wire will measure ok if a single strand is still intact. Best method is using a high power test lamp and measure amps.

[Elboor]

Just measuring continuity of wiring with a multimeter is not good enough. A wire will measure ok if a single strand is still intact. Best method is using a high power test lamp and measure amps.

Yeah I stupidly assumed continuity checks would be enough but thats probably because I started getting lazy as it got cold!! But nothing was "broken" as such so will have to try and hit it all again.

[bob-in-dav]

The only times I've seen flashing three bars turned out to be rear light problems _ - check sidelights and panel lights aren't illuminating when you press the brake pedal.

[mac999]

Faults rectified now it was great meeting you today Seb, anything else you need help with give me a call.

[Elboor]

Cheers mate! Appreciate you coming out and getting the thing going! If anyone in the Hampshire/Wilts area needs Smart/Mercedes diagnostics, thoroughly recommend mac999 - Top bloke, didn't give up and got the little thing going in the end. Very fair price and even chucked in some goodies to help me get the thing up to standard. Has a nice little Brabus Roadster which he gave me a lap in too. Off for MOT Friday, going to take her for a lap tomorrow!