For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptor

DTC P0748: Line Pressure Control Solenoid Valve System Performance - Feedback Current Stuck
DTC P0961: Line Pressure Control Solenoid Valve System Performance - Terminal Short
DTC P0962: Line Pressure Control Solenoid Valve Control Circuit Low Voltage
DTC P0963: Line Pressure Control Solenoid Valve Control Circuit High Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Signal | P0962 | P0748, P0963 | P0748, P0963 | P0961
Low Reference | -- | P0748, P0961, P0963 | P0748, P0961, P0963 | P0748, P0961, P0963

### Typical Scan Tool Data

#### Line PC Solenoid Valve

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Operating Conditions: Engine running, normal operating temperature Parameter Normal Range: 0.1 A to 1.1 A
Signal | 0 A | 2.55 A | 2.55 A
Low Reference | -- | 2.55 A | 1
1. Internal TCM damage may occur if shorted to B+

### Circuit/System Description

Line pressure control solenoid (SLT) is part of the front valve body. SLT regulates the transmission fluid line pressure in accordance with the value decided in the transmission control module (TCM) based on throttle opening signal and engine torque. Through this, it controls operating hydraulic pressure to the clutch and brakes for smooth shifting. The TCM varies the current to the normally SLT from 0.1 A for maximum line pressure, to 1.1 A for minimum line pressure. As a fail-safe function, if SLT abnormality occurs, the TCM will disable the current. In that case the line pressure is maximized.

### Conditions for Running the DTC

#### P0748

• | The ignition voltage is between 10.2 V and 15.5 V.

• | The engine speed is greater than 400 RPM for 2 s.

• | The transmission is not in emergency mode.

• | Driving in D range.

• | TCM communication is normal.

• | DTCs P0962 and P0963 are not set.

#### P0961

• | The ignition voltage is between 10.2 V and 15.5 V.

• | The engine speed is greater than 400 RPM for 2 s.

• | The transmission is not in emergency mode.

• | Driving in D range.

• | TCM communication is normal.

• | The Automatic Transmission Fluid Temperature is more than 20°C (68°F)

• | SLT current is more than 0.85 A.

• | SLT target current is not changed.

#### P0962

• | The ignition voltage is between 10.2 V and 15.5 V.

• | The engine speed is greater than 400 RPM for 2 s.

• | The transmission is not in emergency mode.

• | Driving in D range.

• | TCM communication is normal.

• | DTC P0963 is not set.

#### P0963

• | The ignition voltage is between 10.2 V and 15.5 V.

• | The engine speed is greater than 400 RPM for 2 s.

• | The transmission is not in emergency mode.

• | Driving in D range.

• | TCM communication is normal.

• | DTC P0962 is not set.

### Conditions for Setting the DTC

#### P0748

Deviation between commanded current and feedback current.

#### P0961

The TCM detects the error current more than 80 mA for 2.75 ms.

#### P0962

The TCM detects at least 5 times less than 23 mA current consumption of the SLT control circuit for 100 ms.

#### P0963

The TCM detects at least 5 times more than 1.333 A current consumption of the SLT control circuit for 100 ms.

### Action Taken When the DTC Sets

#### P0748, P0961

• | DTC P0961 is a Type B DTC.

• | The TCM turns OFF all solenoids.

• | The TCM allows the vehicle after a stop to operate only in the second gear and "R" range.

#### P0962, P0963

• | DTCs P0962 and P0963 are Type B DTCs.

• | No self learning function.

• | The TCM turns OFF all solenoids.

• | The TCM allows the vehicle after a stop to operate only in the second gear and "R" range.

### Conditions for Clearing the DTC

#### P0748, P0961

• | DTC P0963 is a Type B DTC.

• | The TCM detects the error current less than 50 mA for 2.75 ms.

#### P0962, P0963

• | DTCs P0962 and P0963 are Type B DTCs.

• | The current consumption of the SLT control circuit is between 0.1 A and 1.1 A for 500 ms.

### Diagnostic Aids

When attempting to set solenoid electrical DTCs, ensure the TCM is warmed up and the transmission is operated in 2nd gear long enough to ensure a 3°C (5°F) increase in TCM substrate temperature. This will place the TCM under the optimal conditions to test solenoid electrical DTCs.

### Reference Information

#### Schematic Reference

Automatic Transmission Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Description and Operation

Transmission Component and System Description

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Ensure the transmission fluid temperature is between 50-80°C (122-176°F).
2. Operate the vehicle in 2nd gear long enough to ensure at least a 3°C (5°F) rise in transmission fluid temperature, then operate the vehicle in Park for 5 s.
3. Observe the scan tool data Line PC Solenoid Valve Current parameter, the reading should be between 0.1 A - 1.1 A.

⇒ | If the parameter in not within specified range or if the DTC resets, go to Circuit/System Testing.

### Circuit/System Testing

Command the Line Pressure Control Solenoid Valve or Increase and Decrease with a scan tool. The value should rise from 0.1 A to 1.1 A and return to 0.1 A.

⇒ | If the value does not change, turn ignition OFF, remove the K71 Transmission Control Module (TCM). Connect a test lamp between the low reference circuit terminal 1 (X2) at the K71 Transmission Control Module (TCM) and the voltage supply component circuit terminal 3 (X2) at the K71 Transmission Control Module (TCM). Command the Line Pressure Control Solenoid Valve or Increase and Decrease with a scan tool. The test lamp has to illuminate brighter with increasing current.

⇒ | If the test lamp always illuminate or always does not illuminate, replace the K71 Transmission Control Module (TCM).

### Component Testing

#### Static Test

1. Ignition OFF, remove the K71 Transmission Control Module (TCM).
2. Test for 5-5.6 Ω at 20°C (68°F) between the low reference circuit terminal 1 (X2) and the voltage supply circuit terminal 3 (X2).

⇒ | If less than the specified range, test the wiring harness for internal short. If the circuit test normal, replace the Q23 Line Pressure Control (PC) Solenoid Valve.

3. Test for infinite resistance between each terminal and the low reference circuit terminal 1 (X2) and also to the voltage supply circuit terminal 3 (X2).

⇒ | If less than the specified range, replace the wiring harness.

4. If all circuit test normal, perform the Control Solenoid Valve Inspection.

⇒ | If the inspection test normal, replace the valve body assembly.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Control valve body replacement. Refer to Control Valve Body Replacement for replacement, setup and programming.

• | TCM, refer to Control Module References for replacement, setup and programming.

⇒ | Perform the Transmission Adaptive Functions.

• | Wiring harness, refer to Automatic Transmission Wiring Harness Replacement for replacement