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No, the gear position sensor reads the position of the gear selector , this is the small round shapped sensor fitted in one side of the gear box. And I read that it is only used when you do a retaught of the gear position with the Star, but you can disconnect it and drive the car without the sensor normally, at least for a short time (I don´t know if from time to time the ECU reads it to crosschek the information given by the gear selector motor encoder). In other hand the gear selector motor has its own encoder built-in inside, this is the one that gives the information to the ECU during normal operation.

Yes it could be the actuator wiring or any other of the wirings because at the same time i was checking all the wires and cleaning all the connectors that goes to the gear box. Do you know if the Star may give a more accurate error, to know if it is related with the actuator, selector motor , or gear sensor? Or just gives an ambiguos error like the P0702 Transmission control system - electrical ? I took the nut off and checked the eyelet (on the roadster there is only one eyelet on that earth point where all the earth wires are crimped ), checked that all wires were strongly attached to the eyelet and cleaned with a sand paper and conatct cleaner spray both the eyelet and the chassis bolt. If I am not wrong on the engine bay the Roadster has an earth point next to the right rear wheel arc and the air box filter and the main ground braided strap that goes to the gear box. I added a ground cable of 25mm2 section on this main ground point , just to help the braided strap. How difficult is this? Aree the bolts accesible? In other hand, I read that the car can run without the gear positition sensor , because it is only used when you do a gear position re-teach, normally te eECU uses the encoder built in the selector motor to know the selector position. But, do you know if from time to time the ECU cross check the information of both sensors? Or it is strictly only used when you re-tech with the Star? Thanks a lot for the help

Hi Willys, thanks for the asnwer. Yes I have already checked the gear box wiring, the connectors and the ground points next to the wheel arc and the one that goes to the gear box. All looks apparently fine. Regarding the actuator, firstly I lubbed it and made the actuator clutch adjustment the with the Star of a colleague, the problem still came randomly after it. Then I changed the actuator by other used one, and for 3 or 4 weeks it looked better, no errors and smooth and faster shifts, but finally suddenly the 3 lines came again. And as usually re-starting the engine solved momentarily the problem. And from time to time when turning the key the car goes through all gears. Checked also the clutch fork and no holes on it. My next steps is going to change the gear box fluid, and after that to check or change the gear sensor and/or the gear selector motor. I need to meet again my coleague to read the error codes with the Star, so far I only could read it with a cheap ELM obd reader that shows the error "P0702 , Estatus. Temporal, Transmission control system - electrical "

Hi, Could you finally find the problem caussing this issue? I am getting a similar problem in a 2003 Smart Roadster , when I turn the key to ON the gearbox goes from 6th to 1st and then N, and then I can start the car as usually. Also sometimes when changing a gear, I get the 3 lines in the speedo, and the car stays in N or clucth dissengaged. The 3 lines dissapear once I stop and restart the car , and the car runs good again. Thanks in advance for any info.

Ok thank you for the information. I am considering buying a Delphi.

Thank you. Is the Delphi (chinese) capable of doing that too? And even log data for a run so later you can analyse it?

I have checked the ground cable that goes from the chassis to the gearbox, where the xhaust bracket is screwed, in fact I added a 25mm2 section cable between these two points to reinforce the ground, so now I have the original ground naked cable plus the new cable. I have visually checked the earth conection in the right wheel arc, but didnt dismount it to do a better inspection and clean it. I just unplugged the connectors from the ECU, sprayed some contact cleaner on tboth sides the ECU and the cable connector and plug them again. I found the pin out of the ECU so my idea was to unplug again the connectors from the ecu and check continuity of the wires between the connector that goes to the ECU and the connectors that goes to the gearbox sensors and actuators. A friend of mine has the Star , so I didnt spend any money in that. We didnt remove the actuator beacuse it looked fine, and well positioned agains the clutch fork so we decided to just make the electronic adjustment, lube it with some white lithium grease in spray and try it. But yeah proabably the next step is to remove it and have a look at the fork arm. I also got another actuator to exchange it, but not sure about it because it lactually looks worse than my current one

So, a part from reading the error codes, how to do that diagnosis? Could you explain me the steps to follow? I have a friend who has the Star , but he is not a professional and I am not sure if he knows the full capabilities of the MB Star. So a kind of guide would be very welcomed.

Yes I checked this wiring around the scoop and apparently looked fine, also cleaned the connectors of the cluct actuator, gear selector motor and gear position sensor with contact cleaner. The rod of the clutch actuator is in contact with the clutch fork, and the ajustment with the MB Star was succesfully, showing 28%. But didnt take the actuator off to check if there is a hole on the fork. The continuity should be checked between the connectors of the gear box (actuator, selector motor and gear sensor) and the ECU connectors?

Hi, any update in te process? I am facing similar issues, When siffting I am getting randomly the 3 bars on my display, and the car stays in N (or with the clutch opened), then I put the shifter in N, turn off and restart the car and the problem goes, and the car runs again. I have checked the wires and connectors and aparently everything is allright. We also did a clutch actuator adjustment with the MB Star, succesfully (didn't move the clutch actuator, though) So an update in your research may be helpful for me. Thanks!