P0798
DTC P0798, P0970, or P0971
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 P0798
- Pressure Control Solenoid Valve 2 System Performance
DTC P0970
- Pressure Control Solenoid Valve 2 Control Circuit Low Voltage
DTC P0971
- Pressure Control Solenoid Valve 2 Control Circuit High Voltage
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The shift control solenoid (SLC2) is installed on the front valve body. The solenoid linearly control hydraulic pressure in response to signals output from the transmission control module (TCM). Through this, the SLC2 controls operating hydraulic pressure to the clutch 2 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
P0798
* The ignition voltage is between 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 P0970 and P0971 are not set.
P0970
* The ignition voltage is between 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 P0971 is not set.
P0971
* The ignition voltage is between 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 P0970 is not set.
Conditions for Setting the DTC
P0798
Deviation between commanded current and feedback current.
P0970
The TCM detects at least 5 times less than 20 mA current consumption of the SLC2 control circuit for 100 ms.
P0971
The TCM detects at least 5 times more than 1 358 mA current consumption of the SLC2 control circuit for 100 ms.
Action Taken When the DTC Sets
P0798
* DTC P0798 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.
P0970, P0971
* DTCs P0970 and P0971 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
P0798
* DTC P0798 is a Type B DTC.
* The TCM detects the error current less than 50 mA for 500 ms.
P0970, P0971
* DTCs P0970 and P0971 are Type B DTCs.
* The current consumption of the SLC2 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 (37°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 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 Pressure Control Solenoid Valve 2 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 Pressure Control Solenoid Valve 2 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 18 at the X2 harness connector
* Control circuit terminal 17 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 18 and the control circuit terminal 17.
• If not between 5-5.6 ohms, perform the Control Solenoid Valve Inspection AF40-6 (MDK) - Automatic Transmission if the inspection fails, replace the control valve body.
• 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.