Diagnostic Procedure
WARNING: This page is about a different car, the 2005 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.
P0594-SPEED CONTROL SERVO POWER CIRCUIT DIAGNOSTIC TEST REFERENCE
| TEST | ACTION | APPLICABILITY |
|---|---|---|
| 1 | Ignition on, engine not running. With the DRBIII®, read DTCs and record the related Freeze Frame data. Is the Good Trip Counter equal to zero? Yes --> Go To 2 No --> Refer to the INTERMITTENT CONDITION SYMPTOM . Perform POWERTRAIN VERIFICATION TEST VER - 4 . |
All |
| 2 | Disconnect the Brake Lamp Switch harness connector. Start the engine. Using a 12-volt test light connected to ground, probe the (V32) S/C Supply circuit in the Switch harness connector while holding the Cruise Switch in the ON position. Does the test light illuminate brightly? Yes --> Go To 3 No --> Go To 7 |
All |
| 3 | Turn the ignition off. Disconnect and remove the Brake Lamp Switch. Measure the resistance across the (V32) S/C Supply circuit terminal and the (V30) S/C Brake Switch Output circuit terminal at the Brake Lamp Switch. Push the Plunger of the Switch in and let it out. Does the resistance change from below 5.0 ohms to an open circuit? Yes --> Go To 4 No --> Replace the Brake Lamp Switch. Perform POWERTRAIN VERIFICATION TEST VER - 4 . |
All |
| 4 | Turn the ignition off. Connect the Brake Lamp Switch harness connector and install the Switch. Disconnect the Speed Control Servo harness connector. Ignition on, engine not running.
NOTE:
It is necessary to PRESS and HOLD the Speed Control Switch in the ON position while checking for voltage. Using a 12-volt test light connected to ground, probe the (V30) S/C Brake Switch Output circuit in the Servo Harness connector. Does the test light illuminate brightly? Yes --> Replace the S/C Servo. Perform POWERTRAIN VERIFICATION TEST VER - 4 . No --> Go To 5 |
All |
| 5 | Turn the ignition off. Disconnect the Brake Lamp Switch harness connector. Measure the resistance of the (V30) S/C Brake Switch Output circuit from the Brake Lamp Switch harness connector to the S/C Servo harness connector. Is the resistance below 5.0 ohms? Yes --> Repair the excessive resistance in the (V30) S/C Brake Switch Output circuit. Perform POWERTRAIN VERIFICATION TEST VER - 4 . No --> Go To 6 |
All |
| 6 | Measure the resistance between ground and the (V30) S/C Brake Switch Output circuit at the Speed Control Servo harness connector. Is the resistance below 100 ohms? Yes --> Repair the short to ground in the (V30) S/C Brake Switch Output circuit. Perform POWERTRAIN VERIFICATION TEST VER - 4 . No --> Go To 9 |
All |
| 7 | Turn the ignition off. Disconnect the C3 PCM harness connector.
CAUTION:
DO NOT PROBE THE PCM HARNESS CONNECTORS. PROBING THE PCM HARNESS CONNECTORS WILL DAMAGE THE PCM TERMINALS RESULTING IN POOR TERMINAL TO PIN CONNECTION. INSTALL MILLER SPECIAL TOOL #8815 TO PERFORM DIAGNOSIS. Measure the resistance of the (V32) S/C Supply circuit from the Brake Lamp Switch harness connector to the appropriate terminal of special tool #8815. Is the resistance above 5.0 ohms? Yes --> Repair the open in the (V32) S/C Supply circuit. Perform POWERTRAIN VERIFICATION TEST VER - 4 . No --> Go To 8 |
All |
| 8 | Measure the resistance between ground and the (V32) S/C Supply circuit in the Brake Switch harness connector. Is the resistance below 100 ohms? Yes --> Repair the short to ground in the (V32) S/C Supply circuit. Perform POWERTRAIN VERIFICATION TEST VER - 4 . No --> Go To 9 |
All |
| 9 |
NOTE:
Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary. Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.If there are no possible causes remaining, view repair.RepairReplace and program the Powertrain Control Module per Service Information.Perform POWERTRAIN VERIFICATION TEST VER - 4 . |
All |