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DTC P1796: Idle-N Control Function Failure
 
 
 
 
 
 
DIAGNOSTIC FUNCTION
TCM determines if the idle neutral control is operating normally.
 
 
JUDGMENT CRITERIA
If the following condition is met during idle neutral control.
  • [(Difference between the engine speed and the turbine speed) - Target slip speed] is greater than 300 r/min for 10 seconds.
 
 
PROBABLE CAUSES
  • Malfunction of turbine speed sensor
  • Damaged wiring harness and connectors
  • Malfunction of forward clutch
 
 
DIAGNOSIS
STEP 1. Check other diagnostic trouble codes.
Are other diagnostic trouble codes set?
Carry out the appropriate troubleshooting.
Go to Step 2.
 
STEP 2. Check the following connector:
  • A-16 Intermediate connector
  • B-120 CVT assembly connector
  • C-130 TCM connector
Check the terminals for a contact status problem and internal short circuit.
Is the check result normal?
Go to Step 3.
Repair the defective connector.
 
STEP 3. Check for open circuit and short to ground in the wiring harness between the CVT assembly connector and the TCM connector.
  • Between B-120 CVT assembly connector (terminal No. 15) and C-130 TCM connector (terminal No. 49)
  • Between B-120 CVT assembly connector (terminal No. 20) and C-130 TCM connector (terminal No. 38)
Is the check result normal?
Go to Step 4.
Repair the wiring harness.
 
STEP 4. Check for open circuit in wiring harness between the CVT assembly connector and the TCM connector.
Between B-120 CVT assembly connector (terminal No. 14) and C-130 TCM connector (terminal No. 48)
Is the check result normal?
Go to Step 5.
Repair the wiring harness.
 
STEP 5. Symptom recheck after erasing diagnostic trouble code
Is the check result normal?
Intermittent malfunction.
Go to Step 6.
 
STEP 6. Turbine speed sensor check
Disassemble the transaxle assembly and visually check the tip of the sensor for foreign materials or damage.
Is the check result normal?
Go to Step 7.
Repair or replace.
 
STEP 7. Check for open circuit or short to ground in the wiring harness between the CVT assembly connector and the turbine speed sensor connector.
Is the check result normal?
Go to Step 8.
Replace the valve body harness.
 
STEP 8. Forward clutch check
Check for facing scorching, failed piston seal rings, retainer interference, etc.
Is the check result normal?
Replace the turbine speed sensor.
Repair or replace the forward clutch.