P0748
DTC P0748, P0962, or P0963
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC P0748
- Line Pressure Control Solenoid Valve System Performance
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
Typical Scan Tool Data
Circuit/System Description
The 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 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 P0962 and P0963 not set.
P0962
* 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 P0963 is not set.
P0963
* 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 P0962 is not set.
Conditions for Setting the DTC
P0748
Deviation between commanded current and feedback current.
P0962
The TCM detects at least 5 times less than 20 mA current consumption of the SLT control circuit for 100 ms.
P0963
The TCM detects at least 5 times more than 1 358 mA current consumption of the SLT control circuit for 100 ms.
Action Taken When the DTC Sets
P0748
* DTC P0748 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 reverse (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 reverse (R) range.
Conditions for Clearing the DTC
P0748
* DTC P0748 is a Type B DTC.
* The TCM detects the error current less than 50 mA for 500 ms.
P0962, P0963
* DTCs P0962 and P0963 are Type B DTCs.
* The current consumption of the SLT control circuit is 0.1-1.1 A for 500 ms.
Diagnostic Aids
When attempting to set solenoid electrical DTCs, ensure the automatic transmission is warmed up and the transmission is operated in 2nd gear long enough to ensure a 3°C (37°F) increase in transmission fluid temperature. This will place the TCM under the optimal conditions to test solenoid electrical DTCs.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics AF40-6 (MDK) - Automatic Transmission
Connector End View Reference
Component Connector End Views Sunshade - Left
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Description and Operation
Transmission Component and System Description Transmission Component and System Description
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. Engine running, ensure the transmission fluid temperature is between 50-80°C (122-176°F).
2. Engine running in Park position, parking brake applied, place the gear select lever in each gear position for 2-3 s. Return the gear select lever to the Park position.
3. Verify the scan tool Line Pressure Control Solenoid Valve Current parameter is between 0.1-1.1 A.
• If the parameter not between 0.1-1.1 A
Refer to Circuit/System Testing
• If the parameter between 0.1-1.1 A
4. Operate the vehicle within the Conditions for Running the DTC. It may be helpful to operate the vehicle within the conditions identified from the Freeze Frame/Failure Records data.
• If the DTC is set
Refer to Circuit/System Testing
• If the DTC is not set
5. All OK.
Circuit/System Testing
1. Engine running at idle, command the Line Pressure Control Solenoid Valve with a scan tool.
2. Verify the value should change from 0.0-1.1 A.
• If the value does not change from 0.0-1.1 A
1. Ignition OFF, and all vehicle systems OFF. Remove the K71 Transmission Control Module to disconnect the X2 harness connector. It may take up to 2 min for all vehicle systems to power down.
2. Test for infinite resistance between ground and the terminals listed below:
* Low reference circuit terminal 1 at the X2 harness connector
* Control circuit terminal 3 at the X2 harness connector
• If less than infinite resistance, replace the wiring harness
• If infinite resistance
3. Test for 5-5.6 ohms at 20°C (68°F) between the low reference circuit terminal 1 and the control circuit terminal 3.
• If not between 5-5.6 ohms, perform the Control Solenoid Valve Inspection AF40-6 (MDK) - Automatic Transmission and repair or replace as necessary.
• If the value changes from 0.0-1.1 A
3. Verify the DTC does not set while operating the vehicle under the Conditions for Running the DTC.
• If the DTC is set
Replace the K71 Transmission Control Module.
• If the DTC is not set
4. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Control valve body replacement, refer to Control Valve Body Replacement Control Valve Body Replacement
* Wiring harness replacement, refer to Automatic Transmission Wiring Harness Replacement Service and Repair
* Refer to Control Module References Control Module References for TCM replacement, programming and setup.
* Perform the Transmission Adaptive Functions Transmission Adaptive Functions.