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 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

Pressure Control Solenoid Valve

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Engine running, normal operating temperature Parameter Normal Range: 0.1-1.1 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 10.2-15.5 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 P2729 and P2730 are not set.

P2728

•	The ignition voltage is 10.2-15.5 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).

•	SLB1 current is more than 0.85 A.

•	SLB1 current is not changed.

P2729

•	The ignition voltage is 10.2-15.5 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 P2730 is not set.

P2730

•	The ignition voltage is 10.2-15.5 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 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 after a stop to operate only in the second gear and “R” range.

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 after a stop to operate only in the second gear and “R” range.

Conditions for Clearing the 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 0.1-1.1 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

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

Circuit/System Testing

Command the Shift Brake Pressure Control Solenoid Valve with a scan tool. The value should change from 0.0-1.0 A.

Component Testing

Static Test

1.	Ignition OFF, remove the K71 Transmission Control Module.

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.

3.	If less than the specified range, test the wiring harness for internal short. If the circuit test normal, replace the Q27E Pressure Control Solenoid Valve 5.

4.	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.

5.	If less than the specified range, replace the wiring harness.

6.	If all circuit test normal, perform the Control Solenoid Valve Inspection (M36 and MXE).

7.	If the inspection test normal, replace the control valve body.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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

•	TCM-Refer to Control Module References.

•	Wiring harness-Refer to Automatic Transmission Wiring Harness Replacement.