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DTC P0551: Power Steering Switch Failure

NOTE: For connector terminal ID, see CONNECTOR IDENTIFICATION . For wiring diagram, see WIRING DIAGRAMS article.
NOTE: Power steering pressure switch is monitored when engine is running. DTC may be stored in Powertrain Control Module (PCM) when vehicle speed is more than 50 MPH for more than 30 seconds and power steering pressure switch remains open.
  1. Connect scan tool to DLC. Monitor Good Trip Counter for P0551. If Good Trip Counter is equal to zero, go to next step. If Good Trip Counter is greater than zero, go to step  6.
  2. Turn ignition off. Disconnect power steering pressure switch connector. Power steering pressure switch is located on steering gear at coupler. Using ohmmeter, check resistance between ground and power steering pressure switch connector Black/Tan wire. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open Black/Tan wire between power steering pressure switch and splice. Perform TEST VER-5A . See WIRING DIAGRAMS article.
  3. Connect one end of jumper wire to power steering pressure switch connector White wire. Turn ignition on. Using scan tool, monitor power steering pressure switch and touch free end of jumper wire to ground several times. If power steering pressure switch status changes from HI to LOW, replace power steering pressure switch. Perform TEST VER-5A . If power steering pressure switch does not change status from HI to LOW, go to next step.
  4. Ensure power steering pressure switch is still disconnected. Disconnect PCM connectors. PCM is located in engine compartment, between air cleaner and radiator. Using ohmmeter, check resistance between ground and PCM connector terminal No. 45 (White wire). If resistance is less than 5 ohms, repair short to ground on White wire between power steering pressure switch and PCM. If resistance is 5 ohms or more, go to next step.
  5. Check resistance of White wire between power steering pressure switch connector and PCM connector terminal No. 45. If resistance is less than 5 ohms, replace PCM. Perform TEST VER-5A . If resistance is 5 ohms or more, repair open White wire. Perform TEST VER-5A .
  6. Check for poor connections or corroded terminals at PCM or power steering pressure switch. Power steering pressure switch is located on steering gear at coupler. Check for intermittent short to ground, open or short to voltage in circuits between PCM and power steering pressure switch. Check for Technical Service Bulletins (TSBs). Repair circuit as necessary. Perform TEST VER-5A . If no problems are found, test is complete.
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