I have nissan primera p12 CVT transimission and the problem is changing gears its use gear 1 only

Could be the sensors or the solenoid switch in the transmission.I recomend it goes to an automatic transmission specialist for repair.

DTC P1778 STEP MOTOR - FUNCTION ...............176 Description ...........................................................176 CONSULT-II Reference Value ..............................176 On Board Diagnosis Logic ...................................176 Possible Cause ....................................................176 DTC Confirmation Procedure ...............................176 WITH CONSULT-II ............................................176 WITH GST ........................................................177 Diagnostic Procedure ...........................................177

DTC P1778 STEP MOTOR - FUNCTION Revision: 2004 November 2004 Murano DTC P1778 STEP MOTOR - FUNCTION PFP:31947 Description ACS0021D ? The step motor's 4 aspects of ON/OFF change according to the signal from TCM. As a result, the flow of line pressure to primary pulley is changed and pulley ratio is controlled. ? This diagnosis item detects when electrical system is OK, but mechanical system is NG. ? This diagnosis item detects when the state of the changing the speed mechanism in unit does not operate normally. CONSULT-II Reference Value ACS0032Q Remarks: Specification data are reference values. On Board Diagnosis Logic ACS0032R ? This is an OBD-II self-diagnostic item. ? Diagnostic trouble code "STEP MOTR/FNC" with CONSULT-II or P1778 without CONSULT-II is detected under the following conditions. - When not changing the pulley ratio according to the instruction of TCM. Possible Cause ACS0032S Step motor DTC Confirmation Procedure ACS0032T CAUTION: ? Always drive vehicle at a safe speed. ? Be careful not to rev engine into the red zone on the tachometer. ? Before starting "DTC Confirmation Procedure", confirm "Hi" or "Mid" or "Low" fixation by "PRI SPEED" and "VEHICLE SPEED" on "DATA MONITOR MODE". ? If hi-geared fixation, go to diagnostic procedure soon. NOTE: If "DTC Confirmation Procedure" has been previously performed, always turn ignition switch OFF and wait at least 5 seconds before performing the next test. After the repair, touch "ERASE" on "SELF-DIAG RESULTS" and then perform the following procedure to confirm the malfunction is eliminated. WITH CONSULT-II 1. Turn ignition switch ON and select "DATA MONITOR" mode for "TRANSMISSION" with CONSULT-II. 2. Make sure that output voltage of CVT fluid temperature sensor is within the range below. FLUID TEMP SEN: 1.0 - 2.0V If out of range, drive the vehicle to decrease the voltage (warm up the fluid) or stop engine to increase the voltage (cool down the fluid) Item name Condition Display value (Approx.) STM STEP (step) During driving -20 step - 190 step GEAR RATIO 2.37 - 0.43

DTC P1778 STEP MOTOR - FUNCTION CVT-177 D E F G H I J K L M A B CVT Revision: 2004 November 2004 Murano 3. Select "DATA MONITOR" mode for "TRANSMISSION" with CONSULT-II. 4. Start engine and maintain the following conditions for at least 30 consecutive seconds. TEST START FROM 0 km/h (0 MPH) CONSTANT ACCELERATION: Keep 30 sec or more VEHICLE SPEED: 10 km/h (6 MPH) or more ACC PEDAL OPEN: More than 1/8 Selector lever: D position ENG SPEED: 450 rpm or more 5. If DTC is detected, go to CVT-177, "Diagnostic Procedure" . WITH GST Follow the procedure "WITH CONSULT-II". Diagnostic Procedure ACS0032U 1. CHECK STEP MOTOR ? It is monitoring whether "GEAR RATIO: 2.37 - 0.43" changes similarly to "STM STEP: -20 - 190" by "DATA MONITOR" mode. Refer to CVT-64, "DATA MONITOR MODE" . ? If no CONSULT-II, inspect the engine speed (rise and descend), vehicle speed, throttle opening angle, and check shift change. OK or NG OK >> INSPECTION END NG >> Replace the transaxle assembly. Refer to CVT-224, "Removal and Installation" . S








Step motor DTC Confirmation Procedure ACS0032T CAUTION: ? Always drive vehicle at a safe speed. ? Be careful not to rev engine into the red zone on the tachometer. ? Before starting "DTC Confirmation Procedure", confirm "Hi" or "Mid" or "Low" fixation by "PRI SPEED" and "VEHICLE SPEED" on "DATA MONITOR MODE". ? If hi-geared fixation, go to diagnostic procedure soon. NOTE: If "DTC Confirmation Procedure" has been previously performed, always turn ignition switch OFF and wait at least 5 seconds before performing the next test. After the repair, touch "ERASE" on "SELF-DIAG RESULTS" and then perform the following procedure to confirm the malfunction is eliminated. WITH CONSULT-II 1. Turn ignition switch ON and select "DATA MONITOR" mode for "TRANSMISSION" with CONSULT-II. 2. Make sure that output voltage of CVT fluid temperature sensor is within the range below. FLUID TEMP SEN: 1.0 - 2.0V If out of range, drive the vehicle to decrease the voltage (warm up the fluid) or stop engine to increase the voltage (cool down the fluid)

code p 1778 refers to CVT step motor--mechanical malfunction===causes ---step motor
the CVT is a constant velocity transmission that has no gear ratios as such but uses a special belt between two pulleys that change flange widths in unison so that as the road speed increases one pulley gets smaller and the other larger
the step motor controls the pulley adjustment
Take it to a service dealer or an accredited specialist transmission shop with experience on that transmission

Peter, I think it is part of or at least goes around the ignition switch.
Check the attached links,instruction and guides, Good luck
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Great quiz question, but without opening the system nobody can tell what broke or came lose. Or where it came lose.it must be in the door that is for sure.

Probably in limp mode. Second gear. Have the codes checked for the transmission/engine and repost.

Start up, leave idling for a few minutes and check the auto trans fluid level on the stick. It should be checked running in Park and be within the limits. I don't know the Primera but it may have a speed sensor that prevent upshift electrically.

Other than taking it back to your mechanic no. You can try google searching it and reading and watch some videos on the problem with the fix for it.

try o put oil in the fuel tank

it sounds like it is overheating have you changed the fluid recently? does it have a transmission cooler? 
These CVT transmissions were never built to be capable of extended offroad driving unless you have the necessary coolers etc