DTC P0551: Power Steering Switch Failure: Testing
- Turn ignition on. Using scan tool, read DTCs. If GLOBAL GOOD TRIP counter is displayed and displayed count is "0", go to next step. If GLOBAL GOOD TRIP counter is not displayed or displayed count is not "0", go to step 6.
- Turn ignition off. Disconnect power steering pressure switch connector. Power steering pressure switch is part of quick disconnect tube near power steering pump and contains a 1-pin connector. Connect on end of a jumper wire to Dark Blue/Light Green wire at power steering pressure switch harness connector. Using scan tool, monitor power steering pressure switch. While observing scan tool, touch other end of jumper wire to ground about 5 times. If power steering pressure switch status changed from hi to low, replace power steering pressure switch. If power steering pressure switch status did not change from hi to low, go to next step.
- Turn ignition off. Disconnect PCM connectors. PCM is located on left side of engine compartment, between Power Distribution Center (PDC) and Transmission Control Module (TCM). See Figure. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance between ground and terminal No. 45 (Dark Blue/Light Green wire) at PCM C2 harness connector. See Figure. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Dark Blue/Light Green wire between PCM and power steering pressure switch.
- Measure resistance of Dark Blue/Light Green wire between power steering pressure switch harness connector and terminal No. 45 at PCM C2 harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Blue/Light Green wire.
- At this time, PCM is assumed to be defective. Replace PCM.
- At this time, conditions required to set DTC are not present. Turn ignition off. Visually inspect related connectors, hoses and wiring harness for damage. Repair connectors, hoses and wiring harness as necessary. If connectors, hoses and wiring harness are okay, test is complete. Check for any related technical service bulletins that may apply.