P0971

DTC P0971: Shift/Cooling Changeover Solenoid System (Short to power supply)

CAUTION:
^ If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines.
^ Whenever the ECU is replaced, ensure that the CAN bus lines are normal.

DIAGNOSTIC FUNCTION
TC-SST-ECU checks that the shift/cooling changeover solenoid circuit is normal.

DESCRIPTIONS OF MONITOR METHODS
The shift/cooling changeover solenoid circuit is determined to be short to power supply.

MONITOR EXECUTION
^ Continuous

MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)

Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
^ P1852: Shift fork 1 or 2 opposite direction movement
^ P1855: Shift fork 3 or 4 opposite direction movement

Sensor (The sensor below is determined to be normal)
^ Not applicable

LOGIC FLOW CHARTS (Monitor Sequence)





DTC SET CONDITIONS

Check Conditions
^ Voltage of battery: 8 V or more.
^ Voltage of battery: 16.5 V or less.
^ Shift/cooling changeover solenoid: OFF.

JUDGMENT CRITERIA
^ FET (Field Effect Transistor) output: (Battery voltage-2 V) or more. (220 millisecond)

OBD-II DRIVE CYCLE PATTERN
The FET channel output remains (Battery voltage-2 V) or less for 220 milliseconds.

PROBABLE CAUSES
^ Malfunction of TC-SST-ECU

DIAGNOSTIC PROCEDURE

STEP 1. Scan tool CAN bus diagnostics
Using scan tool MB991958, diagnose the CAN bus lines.

Q: Is the check result normal?
YES: Go to Step 2.
NO: Repair the CAN bus lines. After repairing the CAN bus line, go to Step 2.

STEP 2. Check whether the DTC is reset.

Q: Is DTC No. P0971 set?
YES: Replace the TC-SST assembly.
NO: Intermittent malfunction.