DTC P0851: Neutral Switch Input Circuit Low

1. OUTLINE OF DIAGNOSIS 
   • Detect the open/short circuit of neutral switch.
   • AT: Judge NG when ECM neutral terminal input is different from reception data from TCM.
   • MT: Judge NG when the neutral switch does not respond even though shift lever is changed (neutral switch is turned on or off by vehicle and engine speed).
2. ENABLE CONDITION 
   ENABLE CONDITION
   
   

   Secondary Parameters	Enable Conditions
   After engine starting	1 second or more
   Starter switch	OFF
   Battery voltage	>8V
   Ignition switch	ON

3. GENERAL DRIVING CYCLE 

   Perform the diagnosis continuously after starting the engine.

4. DIAGNOSTIC METHOD 
   • Abnormality Judgment 

     AT: Judge NG when the continuing time of completing the malfunction criteria below reached to 5 seconds.

     Judgment Value 

     JUDGMENT VALUE
     
     

     Malfunction Criteria	Threshold Value
     Switch signal	ON (Low)
     "P" range / "N" range on AT	OFF
     Any other switches on AT	ON

   • Normality Judgment 

   AT: Judge OK and clear the NG when the malfunction criteria below are completed.

   Judgment Value 

   JUDGMENT VALUE
   
   

   Malfunction Criteria	Threshold Value
   Switch signal	ON (High)
   "P" range / "N" range on AT	OFF
   Any other switches on AT	ON

   MT: Judge NG when the number of times until completing the malfunction criteria below continue 3 times in a row, judge OK when turning to OFF or ON.

   Judgment Value 

   JUDGMENT VALUE
   
   

   Malfunction Criteria	Threshold Value
   Neutral switch on MT	Can not detect ON While changing a) to b)
   Driving condition change Vehicle speed = 0 km/h (0 MPH) & engine speed 600 - 900 rpm Vehicle speed 64 - 106 km/h (40 - 66 MPH) & engine speed 1600 - 2550 rpm

   Time Needed for Diagnosis: 

   • Normal reception from AT is 5 times
   • 3 monitoring on MT

   Malfunction Indicator Light Illumination:  Illuminates when malfunction occurs in 2 continuous driving cycles.

5. DTC CLEAR CONDITION 
   • When the OK idling cycle is completed 40 times in a row
   • When "Clear Memory" was performed
6. MALFUNCTION INDICATOR LIGHT CLEAR CONDITION 
   • When the OK driving cycle was completed 3 times in a row
   • When "Clear Memory" was performed
7. FAIL SAFE 

   None

8. ECM OPERATION AT DTC 

Memorize the freeze frame data. (For test mode $02)