3 bars and can't run gear adaptation

[tolsen]

2003 Smart 450 Passion 700 cc petrol. Car had below faults codes when it arrived:

P2022 Clutch system fault
P203C Actual position of turning angle sensor

Diagnostics kit WinStar Magus version Z0803.

Owner had attempted repair of thin yellow cable (either to pin 3 or 5) leading to transmission gear change motor. He had difficulties getting solder to wet the oxidised copper strands so I sorted that out by wetting the strands in hydrochoric acid to remove the black oxidised layer. Made cable good as new by soldering and added double heat shrink sleeve for insulation and protection.

Proceeded then to carry out gear change adaptation using WinStar. Gear change adaptation did not complete. Heard two or three clonks then nothing. Winstar did not complete gear change adaptation. Reports gear change adaptation not successful and fault code P2035 Turning angle sensor adaptation.

I then proceeded to check all cables from engine control unit to transmission actuators and sensors. Tested the 17 cables twice, first by measuring resistance using multimeter. Secondly by passing current through using a 55 Watts head lamp bulb and power source an old fashioned 12 Volt battery charger. Measured amps around 3.5 A. All tests of transmission cable harness were good.

Car battery is fully charged and being kept on charge with a Lidl intelligent charger.

Tried a brand new clutch actuator but no change. I removed gear change motor and confirmed I can turn the gear change wheels manually hence not seized. Gear change motor does also turn when hot wired to pins 1 & 6.

Looking for some guidance. Obviously my next step will be to check drum rotation sensor and perhaps borrow that one and gear change motor from my Smart Cabrio.

PS. Lucky the forum is back up running. Thanks a lot OMA & al.

[RacingSnake]

First thing I would have checked (which you've done) is the selector motor... so the position sensor seems the next logical step.

Silly question I know, but how old is the clutch? because if it's really really worn, then even the best clutch actuator is not going to have enough throw to fully disengage the clutch to allow free rotation of the gearbox for the adaption to take place?

[tolsen]

Thanks for the advice. Yes it would appear the position sensor (think I called it drum rotation sensor) is the culprit:


Water has entered the internals. Corrosion on rivet connection between pin 1 and resistor. Confirmed by measuring resistance with multimeter. I am hopeful it is possible to repair this sensor by soldering. Too late now to source a replacement at 7 PM on a Saturday.

There were lots of corrosion products in the bore where the o-ring seal is supposed to keep water out. I have to clean all of that and reassemble with plenty of water resistant grease.

Suggest members consider adding this to your to do list. Prevention is the best cure.

[tolsen]

Got it all sorted. Cleaned out area on transmission where the drum rotation sensor (0003254V009) fits. There was quite a lot of white aluminium oxide corrosion products explaining why water was allowed to enter sensor and render it inserviceable. Sourced a 2007 sensor from a donor vehicle and fitted with plenty of protective water repellent grease. Transmission gear adaptation could then be completed successfully and the car would be allowed to start. Car being unable to start and 3 bars was the problem after I had attempted gear adaptation.

A few words about the function and purpose of the drum rotation sensor or gear position sensor part number 0003254V009:

This sensor is only used for diagnostics and for gear change adaptation using MB Star or as in my case WinStar. Attempting gear adaptation with faulty drum totation sensor will result in 3 bars and not able to start engine. Gear position during normal operation comes from the two channel encoder built into the gear change motor. My Smart 450 will run happily with the drum rotation sensor disconnected. Evilution has posted very good details about the workings of the encoder inside clutch actuator. I believe encoder inside gear change motor is nearly same but I have not yet confirmed that by checking signal with a two channel oscilloscope as Evilution has done. Evilution link: http://www.evilution.co.uk/index.php...esting&mod=861

[Evilution]

I do have a gear change motor spare so I will be doing the same just to see. I never knew the gearbox position sensor was for diagnosis and adjustment only, fascinating stuff.

[tolsen]

The purpose of drum rotation sensor and decoder inside gear change motor is explained at end of section 3.3.3 Schaltung of document titled "Das hochintegrierte, automatisierte 6-Gang Schaltgetriebe für den Smart", written by Dipl.-Ing.(FH) Günter Rühle, Dipl.-Ing.(FH) Peter Tillmann, Dipl.-Ing.(BA) Henning Diel, Dipl.-Ing.(FH) Michael Hackenjos GETRAG, Ludwigsburg and published at 7th Aachener Kolloquium: Fahrzeug und Motorentechnik 5 - 7 October 1998 at EUROGRESS Aachen: Die Positionserfassung und Gangerkennung der Schaltwalze erfolgt durch einen Inkrementalgeber, der im Elektromotor integriert ist und parallel aus Gründen der Fehlererkennung durch ein Potentiometer, das direkt durch die Walze angetrieben wird.

Look forward to learn what signal you get from gear change motor.

[Evilution]

I'm expecting the same 2 channel 7 step signal but it's worth checking anyway. I just have to find my pull up resistors.

[Evilution]

Gear change motor, 2 channel, 14 step signal.

[tolsen]

Thanks. So two square waves each generating 14 pulses per revolution.