Hello everyone, this is MAN 18.410 year 2004, automatic transmission. When I put knob in reverse, the light and buzzer do not work. I tested the fuses and the relay, they are ok, but the voltage coming from the computer, which should turn on the relay when it is in reverse, does not come when it is in R or when it is in N, there is only a voltage of 6v that can not deliver current. When I short up the relay contacts (inlet and outlet) the lights turn on and the buzzer works. Could it be an ECU computer or something else? Also to note that the right window switch does not work, lowers the window but it not raises it. Does anyone have any idea what could be, since it is a bit unrealistic for me that the computer is broken.
i have no idea about your speciffic issue however i maybe can give some general advice. What is the switching voltage for the relay? is the window switch on the same circuit as the reversing system? I would suggest that i would check the reversing switch is operating correctly although you may of already done this. I would think that if you should have more than 6v on the signal wire to the relay there must be a load on the system somewhere.
Try to avoid…
Reversing when it’s dark.
Stick your head out the window and go ‘beep beep beep’ quite loudly.
Here to help. 
yourhavingalarf:
Try to avoid…Reversing when it’s dark.
Stick your head out the window and go ‘beep beep beep’ quite loudly.
Here to help.
i always thought that instead of beep beep it should say get out the way you blithering idiot
cooper1203:
i have no idea about your speciffic issue however i maybe can give some general advice. What is the switching voltage for the relay? is the window switch on the same circuit as the reversing system? I would suggest that i would check the reversing switch is operating correctly although you may of already done this. I would think that if you should have more than 6v on the signal wire to the relay there must be a load on the system somewhere.
Situation is this: Idk does the window switch goes trough the same circuit. I found electric diagram, and it says that shifter knob goes inro the main computer, then from computer goes into the gearbox, which changes gears. From cable 71 506 from computer, i should get 24v voltage when it is in R. All relay voltage is 24v
if your sure the signal should be 24 volts try disconecting the signal wire from the relay and putting 24 volts on it and see if the relay operates. if it does it proves the relay works. next step is to see if you are getting the required voltage on the pin out of the ecm if you do then there is either somthing connected to the signal wire other than the relay or there is an issue with the wire its self.