Diagnostic 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

P2728

P2729

P2730

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

P2729, P2730

Conditions for Clearing the DIC/DTC

P2725, P2728

P2729, P2730

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

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