Subaru Legacy BN/BS (2015-2019) Service Manual: Dtc p0966 pressure control solenoid "b" control circuit low

Subaru Legacy BN/BS (2015-2019) Service Manual / Continuously variable transmission (diagnostics) / Diagnostic procedure with diagnostic trouble code (dtc) / Dtc p0966 pressure control solenoid "b" control circuit low

DTC DETECTING CONDITION:

Immediately at fault recognition

TROUBLE SYMPTOM:

Excessive shift shock

1. ENGINE TYPE FB

WIRING DIAGRAM:

CVT control system CVT Control System > WIRING DIAGRAM

STEP	CHECK	YES	NO
1.CHECK INPUT SIGNAL FOR TCM. 1) After driving with warm up condition, park the vehicle while depressing the brake pedal at “D” range. 2) Read the data of «F&R Linear Solenoid Set Current» and «F&R Linear Solenoid Actual Current» using Subaru Select Monitor.	Does the value of «F&R Linear Solenoid Set Current» and «F&R Linear Solenoid Actual Current» almost correspond-	Check for poor contact of connector.	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0966 PRESSURE CONTROL SOLENOID "B" CONTROL CIRCUIT LOW
2.CHECK HARNESS. CAUTION: Start work after ATF cools down. 1) Turn the ignition switch to OFF. 2) Disconnect the TCM connector. 3) Remove the transmission valve cover. 4) Disconnect the control valve body connector. 5) Measure the resistance between TCM connector and chassis ground. Connector & terminal (T10) No. 16 — Chassis ground:	Is the resistance 1 M- or more-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0966 PRESSURE CONTROL SOLENOID "B" CONTROL CIRCUIT LOW	Repair the short circuit of harness.
3.CHECK F&R SOLENOID. 1) Connect the connector for control valve body. 2) Measure the resistance between TCM connector and transmission body. Connector & terminal (T10) No. 16 — Transmission body:	Is the resistance approx. 4 — 6 -- (when cold)	Check for poor contact of connector, and if no fault is found, replace the TCM. Transmission Control Module (TCM)	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0966 PRESSURE CONTROL SOLENOID "B" CONTROL CIRCUIT LOW
4.CHECK HARNESS INSIDE TRANSMISSION. Check for the harness pinch, damage.	Is there any fault in the harness-	Replace the transmission harness.	Replace the control valve body. Control Valve Body

2. ENGINE TYPE EZ

WIRING DIAGRAM:

CVT control system CVT Control System > WIRING DIAGRAM

STEP	CHECK	YES	NO
1.CHECK INPUT SIGNAL FOR TCM. 1) After driving with warm up condition, park the vehicle while depressing the brake pedal at “D” range. 2) Read the data of «F&R Linear Solenoid Set Current» and «F&R Linear Solenoid Actual Current» using Subaru Select Monitor.	Does the value of «F&R Linear Solenoid Set Current» and «F&R Linear Solenoid Actual Current» almost correspond-	Check for poor contact of connector.	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0966 PRESSURE CONTROL SOLENOID "B" CONTROL CIRCUIT LOW
2.CHECK HARNESS. 1) Turn the ignition switch to OFF. 2) Disconnect the TCM and transmission connectors. 3) Measure the resistance between TCM connector and chassis ground. Connector & terminal (B54) No. 16 — Chassis ground:	Is the resistance 1 M- or more-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0966 PRESSURE CONTROL SOLENOID "B" CONTROL CIRCUIT LOW	Repair the short circuit of harness.
3.CHECK F&R SOLENOID. Measure the resistance between transmission connector and transmission body. Connector & terminal (T4) No. 9 — Transmission body:	Is the resistance approx. 4 — 6 -- (when cold)	Check for poor contact of connector, and if no fault is found, replace the TCM. Transmission Control Module (TCM)	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0966 PRESSURE CONTROL SOLENOID "B" CONTROL CIRCUIT LOW
4.CHECK HARNESS INSIDE TRANSMISSION. CAUTION: Start work after ATF cools down. 1) Remove the transmission oil pan. 2) Check for the harness pinch, damage.	Is there any fault in the harness-	Replace the transmission harness.	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0966 PRESSURE CONTROL SOLENOID "B" CONTROL CIRCUIT LOW
5.CHECK HARNESS INSIDE TRANSMISSION. 1) Disconnect the control valve body connector. 2) Measure the resistance between transmission connector and transmission body. Connector & terminal (T4) No. 9 — Transmission body:	Is the resistance 1 M- or more-	Replace the control valve body. Control Valve Body	Replace the transmission harness.

3. OUTLINE OF DIAGNOSIS

• Detect the GND-output short in transmission forward/reverse clutch pressure solenoid circuit.

• Judge as NG if an overcurrent is detected more than 10 times in the transmission forward/reverse clutch pressure solenoid drive circuit.

4. EXECUTION CONDITION

Secondary Parameters	Execution condition
12 V battery system voltage	≥ 9 V

5. DIAGNOSTIC METHOD

If the duration of time while the following conditions are met is longer than the time indicated, judge as NG.

Judgment Value

Malfunction Criteria	Threshold Value
Signal of malfunction from solenoid driver IC	ON
As defined by:
Measured forward & reverse clutch pressure control solenoid current ≥ 1.6 A

Time Needed for Diagnosis: 0.02 seconds

Malfunction Indicator Light Illumination: Illuminates as soon as a malfunction occurs.

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Other materials:

Inspection
1. OPERATION CHECK WHEN NOT USING MEASURING DEVICESCAUTION:When checking operation, be sure to apply the parking brake securely.When an operation check is performed with no measuring devices, a faulty part cannot be identified correctly. But it is possible to identify the outline of the defect by pe ...