Operation CHARM: Car repair manuals for everyone.

P0989




DTC P0989 or P0990

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 P0989
- Transmission Fluid Pressure (TFP) Switch 5 Circuit Low Voltage

DTC P0990
- Transmission Fluid Pressure (TFP) Switch 5 Circuit High Voltage

Diagnostic Fault Information






Typical Scan Tool Data






Circuit/System Description

The transmission fluid pressure (TFP) switch 5 is part of the control solenoid valve assembly which has no serviceable parts. The Transmission Control Module (TCM) supplies a signal circuit to the TFP switch 5. The TFP switch 5 has an internal case ground. TFP switch 5 is normally closed or LOW. When oil pressure is present at the TFP switch 5, the switch is open or HIGH. The normally high pressure control (PC) solenoid 3 controls pressure to the CBR1/4-5-6 clutch regular valve. The TCM monitors the TFP switch 5 signal circuit to determine the position of the CBR1/4-5-6 clutch regulator valve. When the 4-5-6 clutch is commanded OFF, pressure is present on the TFP switch 5. When the 4-5-6 clutch is commanded ON, the CBR1/4-5-6 clutch regulator valve moves and pressure to the TFP switch 5 is exhausted through the CBR1/4-5-6 clutch regulator valve.

Conditions for Running the DTC

P0989 or P0990
* No other ECM or TCM DTCs are set.
* The ignition voltage is 8.6 volts or greater.
* The transmission fluid is -6.6°C (20°F) or greater.
* The engine speed is 400 RPM or greater for 5 seconds.
* The high side driver is commanded ON.

Conditions for Setting the DTC

P0989

The TCM detects that the TFP switch 5 signal voltage remains LOW after the 4-5-6 clutch transitions from a HIGH pressure state to a LOW pressure state. The TCM counts each incident. The DTC sets when 18 counts are accumulated.

P0990

The TCM detects that the TFP switch 5 signal voltage remains HIGH after the 4-5-6 clutch transitions from a LOW pressure state to a HIGH pressure state. The TCM counts each incident. The DTC sets when 15 counts are accumulated.

Action Taken When the DTC Sets

* DTCs P0989 and P0990 are Type C DTCs.
* The TCM freezes transmission adaptive functions.

Conditions for Clearing the DTC

DTCs P0989 and P0990 are Type C DTCs.

Diagnostic Aids

A TFP switch may malfunction due to normal debris in the transmission fluid causing a TFP Switch DTC to intermittently set. This type of condition should not be immediately noticeable to a customer, as the switch outputs are used for shift adaptive pressure and do not cause transmission symptoms unless the switch malfunctions continuously for an extended period of time.

Reference Information
Schematic Reference

Automatic Transmission Controls Schematics Electrical Diagrams
Connector End View Reference

* Component Connector End Views Connector Views
* Inline Harness Connector End Views X101

Description and Operation

* Electronic Component Description Electronic Component Description
* Transmission General Description Transmission General Description
* Transmission Component and System Description Transmission Component and System Description

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

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
Special Tools

DT-47825-10 - Jumper Harness

For equivalent regional tools, refer to Special Tools Tools and Equipment.

Circuit/System Verification

1. Engine idling in Park with parking brake applied, and drive wheels chocked.
2. Monitor the Transmission Fluid Pressure Switch 1, Transmission Fluid Pressure Switch 3, Transmission Fluid Pressure Switch 4, and Transmission Fluid Pressure Switch 5 parameters with a scan tool.
3. Place the gear select lever in Park, Reverse, and Neutral range. Verify the TFP switch parameter states are correct for each range. Refer to Transmission Fluid Pressure Switch Logic Transmission Fluid Pressure Switch Logic.

If the switch logic is incorrect for a given gear range
Refer to Circuit/System Testing below.

If the switch logic is correct for all gear ranges

4. Place the gear select lever in Drive range. Command the shift transmission with a scan tool through all forward ranges. Verify the TFP switch parameter states are correct for each range. Refer to Transmission Fluid Pressure Switch Logic Transmission Fluid Pressure Switch Logic.

If the switch logic is incorrect for a given range
Refer to Circuit/System Testing below.

If the switch logic is correct for all gear ranges

5. After performing the above steps, verify that the DTC does not reset by operating the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data. If the vehicle passes the Circuit/System Verification procedure then STOP. Do not perform the Circuit/System Testing or Component Testing as this may result in an unnecessary part replacement. Refer to Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections.

Circuit/System Testing

Note: You must perform the Circuit/System Verification first.

1. Ignition OFF. Remove the Q8 control solenoid valve assembly. Refer to Control Solenoid Valve and Transmission Control Module Assembly Replacement Service and Repair.
2. Inspect the Q8 control solenoid valve and transmission control module assembly. The Q8 control solenoid valve and transmission control module assembly must be externally cleaned of all debris and each solenoid resistance value must be within the specified range. Refer to Control Solenoid Valve and Transmission Control Module Assembly Inspection Control Solenoid Valve and Transmission Control Module Assembly Inspection.

If the solenoid resistance is not within the specified range
Replace the Q8 control solenoid and transmission control module assembly.

If the solenoid resistance is within the specified ranges

3. Place the Q8 control solenoid valve assembly on a clean work surface near the transmission assembly.
4. Connect the DT-47825-10 - jumper harness between the vehicle wire harness electrical connector, and the Q8 control solenoid valve assembly electrical connector.
5. Ignition ON, verify with a scan tool that each TFP switch parameter changes states when gently pushing on each TFP switch with the eraser end of a pencil.

If any TFP switch parameter does not change states
Replace the Q8 control solenoid valve assembly.

Repair Instructions

* Perform the Reset Transmission Adapts Reset Procedure following all transmission related repairs.
* Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Refer to Control Module References Control Module References for control solenoid valve assembly replacement, programming, and setup.