DTC P0551: Power Steering Switch Failure: Testing
- Turn ignition on, engine off. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0551 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0551 and displayed count is not "0", go to step 7.
- Turn ignition off. Disconnect power steering pressure switch connector. Power steering pressure switch is located in pressure line near power steering pump. See Fig 1. Using DVOM, measure resistance between ground and power steering pressure switch connector terminal No. 1 (Black wire). See Fig 2. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black wire between power steering pressure switch and ground connection G119. Ground connection G119 is located near front of right-side valve cover, near A/C compressor. See WIRING DIAGRAMS article.
- Ensure power steering pressure switch connector is still disconnected. Turn ignition on, engine off. Connect jumper wire to power steering pressure switch harness connector terminal No. 2 (Dark Blue/Orange wire). Using scan tool, monitor power steering pressure switch status while momentarily touching other end of jumper wire several times to power steering pressure switch connector terminal No. 1 (Black wire). If power steering pressure switch status does not change from high to low, remove jumper wire and go to next step. If power steering pressure switch status changes from high to low, remove jumper wire and replace power steering pressure switch.
- Ensure ignition is off and power steering pressure switch connector is still disconnected. Disconnect PCM connectors. PCM is located in engine compartment on passenger-side inner fender panel. Using DVOM, measure resistance between ground and PCM harness connector C1 terminal No. 12 (Dark Blue/Orange wire). 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/Orange wire between power steering pressure switch and PCM.
- Ensure ignition is off and power steering pressure switch and PCM connectors are still disconnected. Using DVOM, measure resistance of Dark Blue/Orange wire between PCM harness connector C1 terminal No. 12 and power steering pressure switch harness connector terminal No. 2. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Blue/Orange wire between power steering pressure switch and PCM.
- At this time, PCM is assumed to be defective. Replace PCM.
- Turn ignition off. Inspect wiring harness and connectors between PCM and power steering pressure switch. Inspect PCM connectors and power steering pressure switch connector for corroded, pushed out or damaged terminals. Also, check for related Technical Service Bulletins (TSBs). If terminals are not corroded, pushed out or damaged and wiring harness is okay, test is complete. If terminals are corroded, pushed out or damaged, or wiring harness is damaged, repair as necessary.
Courtesy of DAIMLERCHRYSLER CORPORATION
Courtesy of DAIMLERCHRYSLER CORPORATION