P0777-SECONDARY PRESSURE SOLENOID STUCK ON (LOW PRESSURE)

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1 009 - MK - JEEP COMPASS/PATRIOT -.0L 4 CYL DOHC 6V DUAL V.V.T. P0777-SECONDARY STUCK ON (LOW ) / LINE SECONDARY ON/OFF 3 4 T0 DG/LB T9 T9 T60 YL/DB YL/LB YL/GY C C 3 C 4 C LINE SECONDARY ON/OFF MODULE- BLACK WHITE / MODULE- C (CVT) 874a For a complete wiring diagram, refer to the Wiring Information.

2 Theory of Operation The Transmission Control Module (TCM) monitors the secondary line pressure (secondary pulley pressure) from the secondary pressure sensor. The TCM compares the actual secondary line pressure to the target (desired) line pressure. Failure to match the target line pressure over a given time will set the DTC. When Monitored: Ignition on, engine running with the transmission not in neutral or park. Transmission fluid temperature greater than -0 C (-4 F). Brake Switch in the OFF mode. Change rate of vehicle speed greater than 4 Km/h ( mph). Change rate of accelerator pedal position less than ± 6.%. Engine rpm greater than 40 rpm with a transmission fluid temperature greater than 0 C (68 F). No active DTCs from the following: Set Condition: When the secondary pressure goes down gradually below a predetermined value during a drive cycle. The DTC could be due to the failure of the secondary pressure control system, secondary pressure solenoid performance or line pressure solenoid. There are two possible setting conditions to set this DTC. Condition one: Target secondary pressure minus the measured secondary pressure is greater than 0. MPa (36 psi) for two consecutive instances of a problem identification for the period of. seconds within a 30 second interval. Condition two: Target secondary pressure minus the measured secondary pressure is greater than.0 MPa (9 psi) for the period of 800 msec. Possible Causes (T0) SECONDARY SENSOR SIGNAL CIRCUIT LINE SECONDARY SENSOR SECONDARY SECONDARY SYSTEM MODULE Always perform the CVT Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 8 - DTC-Based Diagnostics/MODULE, Transmission Control (TCM) - Standard Procedure).. CHECK IF THE DIAGNOSTIC TROUBLE CODE (DTC) IS ACTIVE. Using the scan tool, read Transmission DTCs.

3 Is the status Active for this DTC or is the Starts Since Set counter or less? Yes Go To No Go To 7. CHECK LINE Approximate Engine rpm to Line pressure readings Engine rpm Idle.0L - 00 to 3000 rpm.4l to 300 rpm Line Pressure 70 kpa (08.8 psi) ± 400 kpa (8 psi) kpa ( psi) ± 400 kpa (8 psi). Start the engine and warm the transmission to 0-80 C ( - 74 F).. Turn the ignition off to the lock position. 3. Install an appropriate pressure gauge in the Line Pressure test port in accordance with the Service Information. WARNING: The CV Transmission can generate a line pressure up to 00 psi. Failure to use recommended test equipment referred to by the Service Information can result in possible serious or fatal injury. 4. Using the scan tool, erase Transmission DTCs. WARNING: Apply the parking brake. Failure to follow these instructions can result in possible serious or fatal injury.. With the brakes firmly applied, start the engine allow to idle and shift the transmission into Reverse, Drive and Low while recording the scan tool Line pressure reading and the pressure gauge reading in each shift lever position. 6. With the brakes still firmly applied, raise the engine rpm between rpm and shift the transmission into Reverse, Drive and Low while recording the scan tool line pressure reading and the pressure gauge reading in each shift lever position. CAUTION: Do not hold the engine rpm between rpm for more than seconds in any given shift position. If the five second threshold is exceeded, transmission damage can occur. Allow to idle in neutral between shifts for at least to 0 seconds to allow transmission fluid to cool. Do the gauge readings fall into the desired pressure ranges? Yes Go To 4 No Go To 3 3. VERIFY PROBLEM Possible causes to conditions detected ENGINE RPM LINE CONDITION DETECTED POSSIBLE CAUSES BUT NOT JUST LIMITED TO THESE Idle speed Low for all shift lever positions Oil Pump Wear 3

4 ENGINE RPM Engine rpm between 700 and 30 rpm LINE CONDITION DETECTED Only low for a specific position High Line pressure does not rise above the line pressure at idle Line Pressure rises but does not reach desired level Line pressure is low in only one shift lever position POSSIBLE CAUSES BUT NOT JUST LIMITED TO THESE Pressure Regulator Valve for plug sticking or spring fatigue Oil filter, oil pump, pressure regulator valve passage oil leak Engine idle speed too low Oil pressure leak in a passage or component related to the position after the pressure is distributed by the manual valve TP or APP sensor signal malfunction CVT fluid temperature sensor malfunction Line pressure solenoid sticking in the off state, filter plugged, cut line Pressure regulator valve or plug sticking TP or APP sensor signal malfunction Line pressure solenoid sticking in the on state, filter plugged Pressure regulator valve or plug sticking Transmission Control Module (TCM) Oil pump weak or worn TP or APP sensor signal malfunction Line pressure solenoid sticking in the off state, filter plugged, cut line Pressure regulator valve or plug sticking Oil pump weak or worn Oil pressure leak in a passage or component related to the position after the pressure is distributed by the manual valve. Use the above chart to help identify the possible cause. NOTE: There may be other possible causes besides those listed on the above chart. Review any Service Bulletins and refer to the Service Information for any additional possible causes that may apply. 4

5 Repair Repair the CV Transmission as necessary in accordance with the Service Information Perform the CVT VERIFICATION TEST. (Refer to 8 - DTC-Based Diagnostics/MODULE, Transmission Control (TCM) - Standard Procedure). 4. CHECK THE SECONDARY. Turn the ignition off to the lock position.. Disconnect the pressure gauge from the Line Pressure test port and reinstall the test port plug. 3. Install the pressure gauge in the Secondary Pressure test port in accordance with the Service Information. 4. Using the scan tool, erase Transmission DTCs. WARNING: Apply the parking brake. Failure to follow these instructions can result in possible serious or fatal injury.. With the brakes firmly applied, start the engine allow to idle and shift the transmission into Reverse, Drive and Low while comparing the Secondary Pressure gauge reading to the scan tool Secondary Pressure reading in each shift lever position and record your findings. 6. With the brakes still firmly applied, raise the engine rpm between rpm and shift the transmission into Reverse, Drive and Low while comparing the gauge Secondary Pressure to the scan tool Secondary Pressure in each shift lever position and record your findings. CAUTION: Do not hold the engine rpm between rpm for more than seconds in any given shift position. If the five second threshold is exceeded, transmission damage can occur. Allow to idle in neutral between shifts for at least to 0 seconds to allow transmission fluid to cool. Does the Secondary Pressure gauge readings match the scan tool readings in all of the above procedures? Yes Replace the Valve Body in accordance with the Service Information for components related to the Secondary Pressure Control System. Perform the CVT VERIFICATION TEST. (Refer to 8 - DTC-Based Diagnostics/MODULE, Transmission Control (TCM) - Standard Procedure). No Go To

6 . CHECK THE SECONDARY SENSOR. Turn the ignition off to the lock position.. Disconnect the pressure gauge from the Secondary Pressure test port and reinstall the test port plug. 3. Disconnect the Transmission Solenoid/Pressure Switch Assembly harness connector. 4. Connect a jumper wire between the (T0) Secondary Pressure Sensor Signal circuit and the (T7) -Volt Supply circuit in the Transmission Solenoid/Pressure Switch Assembly harness connector.. Ignition on, engine not running. BLACK With the scan tool read the Secondary Pressure voltage. Is the voltage between 4. and. Volts? / Yes Replace the Secondary Pressure Sensor (Valve Body) in accordance with the Service Information Perform the CVT VERIFICATION TEST. (Refer to 8 - DTC-Based Diagnostics/ MODULE, Transmission Control (TCM) - Standard Procedure). No Go To 6 6. CHECK THE (T) PRIMARY SENSOR SIGNAL CIRCUIT FOR HIGH RESISTANCE. Turn the ignition off to the lock position.. Disconnect the TCM C harness connector. 3. Connect a jumper wire between the B(+) and the (T) Primary Pressure Sensor Signal circuit in the Transmission Solenoid/Pressure Switch harness connector. 4. Using a -volt test light connected to ground, check the (T) Primary Pressure Sensor Signal circuit in the TCM C harness connector. NOTE: The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery. / BLACK 9 7 (+) LT. GRAY Does the test light illuminate brightly? 4 9 Yes Using the schematics as a guide, check the Transmission Control Module (TCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. Check for any Service Bulletins for possible causes that may apply. If no problems MODULE- C (CVT)

7 are found, replace the TCM in accordance with the Service Information. Perform the CVT VERIFICATION TEST. (Refer to 8 - DTC-Based Diagnostics/ MODULE, Transmission Control (TCM) - Standard Procedure). No Repair the (T) Primary Pressure Sensor Signal circuit for an open (high resistance). Perform the CVT VERIFICATION TEST. (Refer to 8 - DTC-Based Diagnostics/ MODULE, Transmission Control (TCM) - Standard Procedure). 7. INTERMITTENT WIRING AND CONNECTORS. The conditions necessary to set this DTC are not present at this time.. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit. 3. Wiggle the wires while checking for shorted and open circuits. Were there any problems found? Yes Repair as necessary. Perform the CVT VERIFICATION TEST. (Refer to 8 - DTC-Based Diagnostics/MODULE, Transmission Control (TCM) - Standard Procedure). No Test Complete. 7