Took my 2005 Infiniti g35x sedan to a garage today to check out manual mode issue. Car does not always go into manual mode.Mechanic said it was the manual mode switch.Was showing code1815. I was informed that you can not just replace the switch but must purchase whole shifter assembly. Is this true? If so,what is the part number for the assembly and cost of part and labor? Don't know if it is worth it . Thanks. PS garage was not an Infiniti dealer

 

Here for the comments.

 

Does tiptronic ever work, or just intermittent problems? Mine works most the time but restarting the car always fixes it for the time being. I throw the same code but it makes me think that since a restart works for me it could be electrical. The switch is part of the assembly so you would have to buy a new or used one and swap it out. Try cleaning all your grounds and inspect the contacts on the shift switch

 

It is intermittent and does work on restarts.Where are these electrical connections? Is a new assembly expensive? Maybe I will live with it Thank you