For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle

• | Review Strategy Based Diagnosis

• | Diagnostic Procedure Instructions

### DTC Descriptors

DTC P2725: Brake Band Pressure Control Solenoid Valve Control Circuit Shorted
DTC P2728: Brake Band Pressure Control Solenoid Valve Performance
DTC P2729: Brake Band Pressure Control Solenoid Valve Control Circuit Low Voltage
DTC P2730: Brake Band Pressure Control Solenoid Valve Control Circuit High Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Signal | P2729 | P2730 | P2730 | P2725, P2728
Low Reference | -- | P2725, P2728, P2730 | P2725, P2728, P2730 | P2725, P2728, P2730

### 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

The shift control solenoid (SLB1) is installed on the front valve body. The solenoid linearly controls hydraulic pressure in response to signals output from the transmission control module TCM. Through this, the SLB1 controls operating hydraulic pressure to the brake for smooth shifting. According to each shift control solenoid assembly, the transmission shifts from 1st gear into 6th gear and vice versa. As a fail-safe function, if any shift control solenoid assembly abnormality occurs, the TCM will disable the current to the solenoids.

### Conditions for Running the DTC

#### P2725

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

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

• | The transmission is not in emergency mode.

• | Driving in D range.

• | TCM communication is normal.

• | DTCs P2729 and P2730 are not set.

#### P2728

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

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

• | 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)

• | SLB1 current is more than 0.85 A.

• | SLB1 target current is not changed.

#### P2729

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

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

• | The transmission is not in emergency mode.

• | Driving in D range.

• | TCM communication is normal.

• | DTC P2730 is not set.

#### P2730

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

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

• | The transmission is not in emergency mode.

• | Driving in D range.

• | TCM communication is normal.

• | DTC P2729 is not set.

### Conditions for Setting the DTC

#### P2725

Deviation between commanded current and feedback current.

#### P2728

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

#### P2729

The TCM detects at least 5 times less than 23 mA current consumption of the SLB1 control circuit for 100 ms.

#### P2730

The TCM detects at least 5 times more than 1.333 A current consumption of the SLB1 control circuit for 100 ms.

### Action Taken When the DTC Sets

#### P2725, P2728

• | DTC P2725 and P2728 are Type B DTC.

• | The TCM turns OFF all solenoids.

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

#### P2729, P2730

• | DTCs P2729 and P2730 are Type B DTCs.

• | No self learning function.

• | The TCM turns OFF all solenoids.

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

### Conditions for Clearing the DIC/DTC

#### P2725, P2728

• | DTC P2725 and P2728 are Type B DTC.

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

#### P2729, P2730

• | DTCs P2729 and P2730 are Type B DTCs.

• | The current consumption of the SLB1 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 in the optimal condition 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

### 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 Brake Band Pressure Control Solenoid Valve Current parameter, the reading should be between 0.1 A -1.1 A.

### Circuit/System Testing

1. Command the Shift Brake PC 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 16 (X2) at the K71 Transmission Control Module (TCM) and the voltage supply component circuit terminal 21 (X2) at the K71 Transmission Control Module (TCM). Command the Shift Brake PC 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 illuminates 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 16 (X2) and the voltage supply circuit terminal 21 (X2).

⇒ | If less than the specified range, test the wiring harness for internal short. If the circuit test normal, replace the Q27C Pressure Control (PC) Solenoid Valve.

3. Test for infinite resistance between each terminal and the low reference circuit terminal 16 (X2) and also to the voltage supply circuit terminal 21 (X2).

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

4. If all circuit test normal, perform the control solenoid valve inspection Control Solenoid Valve Inspection

⇒ | If the inspection tests normal, replace the control valve body.

### Repair Instructions

Perform the Diagnostic Repair Verification

• | Control valve body replacement. Refer to Control Valve Body Replacement

• | TCM, refer to Control Module References

⇒ | Perform the.

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