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P0872



DTC P0842, P0847, or P0872

Diagnostic Instructions

* Perform theDiagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* ReviewStrategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



DTC Descriptors
DTC P0842
- Transmission Fluid Pressure (TFP) Switch 1 Circuit Low Voltage

DTC P0847
- Transmission Fluid Pressure (TFP) Switch 2 Circuit Low Voltage

DTC P0872
- Transmission Fluid Pressure (TFP) Switch 3 Circuit Low Voltage




Diagnostic Fault Information






Typical Scan Tool Data






Circuit/System Description

The pressure switch manifold (PSM) is a multiple switch assembly made up of 3 normally open (N/O) pressure switches and 1 normally closed (N/C) pressure switch. Pressure switch 1 (PS1) monitors shift valve 1 positioning, Pressure switch 2 (PS2) monitors shift valve 2 positioning, and Pressure switch 2 (PS3) monitors shift valve 3 positioning. The pressure switches communicate the positioning to the transmission control module (TCM).


Conditions for Running the DTC


P0842
* The engine is running for a minimum of 5 seconds.
* Ignition voltage is greater than 9.0 V and less than 18 V.
* Shift valve 1 is commanded to the OFF, or destroked position.



P0847
* The engine is running for a minimum of 5 seconds.
* Ignition voltage is greater than 9.0 V and less than 18 V.
* Shift valve 2 is commanded to the OFF, or destroked position.



P0872
* The engine is running for a minimum of 5 seconds.
* Ignition voltage is greater than 9.0 V and less than 18 V.
* Shift valve 3 is commanded to the OFF, or destroked position.



Conditions for Setting the DTC

P0842

This DTC sets during steady state operation when shift solenoid 1 (SS1) is commanded OFF and PS1 indicates ON for 1 second.

P0847

This DTC sets during steady state operation when shift solenoid 2 (SS2) is commanded OFF and PS2 indicates ON for 1 second.

P0872

This DTC sets during steady state operation when shift solenoid 3 (SS3) is commanded OFF and PS3 indicates ON for 1 second.


Action Taken When the DTC Sets


P0842
* The TCM requests the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL).
* When in a forward range and shifting is completed, the transmission will shift to another forward range, unless the transmission is compromised by overspeeding or direction change, then the transmission will shift to NEUTRAL.
* While diagnostic response is active, if shift selector is moved to neutral, the transmission will shift to neutral. If the transmission is shifted to reverse (R), the transmission will shift to REVERSE. If the shift selector is moved to a forward range or reverse and transmission is compromised by overspeeding or direction change, transmission shifts to neutral.
* DTC P0842 is stored in TCM history.
* The TCM freezes shift adapts.
* The TCM inhibits torque converter clutch (TCC) engagement.



P0847
* The TCM requests the ECM to illuminate the MIL.
* When in a forward range and shifting is completed, the transmission will shift to another forward range, unless the transmission is compromised by overspeeding or direction change, then the transmission will shift to NEUTRAL
* While diagnostic response is active, if shift selector is moved to neutral, the transmission will shift to neutral. If the transmission is shifted to reverse (R), the transmission will shift to REVERSE. If the shift selector is moved to a forward range or reverse and transmission is compromised by overspeeding or direction change, transmission shifts to neutral.
* DTC P0847 is stored in TCM history.
* The TCM freezes shift adapts.
* The TCM inhibits TCC engagement.



P0872
* The TCM requests the ECM to illuminate the MIL.
* When in a forward range and shifting is completed, the transmission will shift to another forward range, unless the transmission is compromised by overspeeding or direction change, then the transmission will shift to NEUTRAL.
* While diagnostic response is active, if shift selector is moved to neutral, the transmission will shift to neutral. If the transmission is shifted to reverse (R), the transmission will shift to REVERSE. If the shift selector is moved to a forward range or reverse and transmission is compromised by overspeeding or direction change, transmission shifts to neutral.
* DTC P0872 is stored in TCM history.
* The TCM freezes shift adapts.
* The TCM inhibits TCC engagement.



Conditions for Clearing the DTC

DTC P0842, P0847, and P0872 are Type A DTCs.


Diagnostic Aids


P0842
* You may have to drive the vehicle in order to experience a condition.
* This DTC may indicate that SS1 is mechanically defective.
* When DTCs P0752 and P0842 are set in combination, this may indicate a grounded circuit condition on the pressure switch circuit or the shift valve 1 is stuck in the stroked position.



P0847
* You may have to drive the vehicle in order to experience a condition.
* This DTC may indicate that SS2 is mechanically defective.
* When DTCs P0757 and P0847 are set in combination, this may indicate an open circuit condition on the pressure switch circuit or the shift valve 2 is stuck in the stroked position.



P0872
* You may have to drive the vehicle in order to experience a condition.
* This DTC may indicate that SS3 is mechanically defective.
* When DTCs P0762 and P0872 are set in combination, this may indicate an grounded circuit condition on the pressure switch circuit or the shift valve 3 is stuck in the stroked position.



Reference Information
Schematic Reference

Automatic Transmission Controls Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

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

Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information


Circuit/System Verification

1. Engine running, command the transmission through the forward ranges with a scan tool. Compare the TFP Switch 1, TFP Switch 2, and TFP Switch 3 parameters in each forward range with the Pressure Switch Manifold Logic table. Refer to Pressure Switch Manifold (PSM) Logic (Pressure Switch Manifold (PSM) Logic) .
2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.



Circuit/System Testing



Note

You must perform the Circuit/System verification first.

1. Ignition ON, engine OFF, verify with a scan tool the TFP Switch 1, TFP Switch 2 and TFP Switch 3 parameters are High.

• If TFP Switch 1, TFP Switch 2, and TFP Switch 3 parameters are the specified value, refer toControl Valve Body Assembly Disassemble (Overhaul) andControl Valve Body Cleaning and Inspection (Overhaul) .
• If valve body inspection is normal, replace the Shift Solenoid indicated by the DTC, refer toControl Valve Solenoid Replacement (SS1, SS2, SS3, TCC, and MAIN MOD) (Control Valve Solenoid Replacement (SS1, SS2, SS3, TCC, and MAIN MOD))Control Valve Solenoid Replacement (PCS1 and PCS2) (Control Valve Solenoid Replacement (PCS1 and PCS2)) .

2. Ignition OFF, disconnect the X175 harness connector at the transmission.
3. Ignition ON, engine OFF, verify with a scan tool the TFP Switch 1, TFP Switch 2, and TFP Switch 3 parameters are High.

• If not the specified value, test the affected pressure switch signal circuit for a short to ground. If circuits tests normal, replace the TCM.

4. Remove the transmission oil pan. Refer to Oil Pan Replacement (Service and Repair) .
5. Test the transmission internal Pressure Switch 1, 2, and 3 signal circuits for a short to ground.

• If the circuits test normal, replace the PSM. Refer to Pressure Switch Manifold Replacement (Service and Repair) .




Repair Instructions

Perform theDiagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Pressure Switch Manifold Replacement (Service and Repair)
* Control Valve Solenoid Replacement (SS1, SS2, SS3, TCC, and MAIN MOD) (Control Valve Solenoid Replacement (SS1, SS2, SS3, TCC, and MAIN MOD))Control Valve Solenoid Replacement (PCS1 and PCS2) (Control Valve Solenoid Replacement (PCS1 and PCS2))
* Control Module References (Programming and Relearning) for TCM replacement, setup, and programming.



Repair Verification

If another DTC is present, refer toDiagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code Descriptions) and perform the appropriate diagnostic procedure.

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