P0971

DTC P0971: Shift/Cooling Switching 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 switching solenoid circuit is normal.

DESCRIPTIONS OF MONITOR METHODS

The shift/cooling switching 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 switching 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
- Malfunction of shift/cooling switching solenoid

DIAGNOSTIC PROCEDURE

Required Special Tools:

- MB991958 Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827 M.U.T.-III USB Cable
- MB991910 M.U.T.-III Main Harness A

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. CAN Bus Diagnostics Chart.) 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 transaxle assembly. (Refer to Removal and Replacement.)
NO Intermittent malfunction. How to Cope With Intermittent Malfunctions.)