P0551

P0551-POWER STEERING PRESSURE SWITCH PERFORMANCE

For a complete wiring diagram consult Diagrams/Electrical.


- When Monitored:
With the engine running.

- Set Condition:
With the vehicle above 40 m.p.h. for over 30 seconds, the Power Steering Switch remains open. Two Trip Fault. Three good trips to turn off the MIL.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview.


Diagnostic Test


1. DTC IS ACTIVE
Turn the ignition on.
With the scan tool, select View DTCs. Record DTC and Freeze Frame information.
Start the engine and allow it to reach operating temperature.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.


NOTE: Review Freeze Frame information. Operate the vehicle under conditions similar to which the DTC was set.

With a scan tool, select View DTCs.
Is the status Active for this DTC?

Yes


- Go to 2


No


- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.Checking For An Intermittent DTC




2. POWER STEERING SWITCH
Turn the ignition off.
Disconnect the Power Steering Switch connector.
Turn the ignition on.
Using the scan tool, monitor the Power Steering Pressure Switch status.
Connect a jumper wire between the (K66) P/S Signal circuit and the (Z988) Ground circuit in the Power Steering Switch harness connector.
Does the switch status on the scan tool change from High to Low when connecting and disconnecting the jumper wire?

Yes


- Replace the Power Steering Switch.
- Perform the PCM Verification Test.Powertrain Verification Test


No


- Go to 3




3. (K66) P/S SIGNAL CIRCUIT HIGH RESISTANCE
Turn the ignition off.
Connect the Power Steering Switch 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 along with the #8815-1 to perform the diagnosis.

Using a voltmeter, perform a voltage drop test by backprobing the (K66) P/S Signal circuit at the Power Steering Switch harness connector and probing the appropriate terminal of the special tool #8815. Make sure the voltmeter leads are connected so that positive polarity is displayed on the voltmeter.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

Start the engine.
Is the voltage below 0.5 volts?

Yes


- Go to 4


No


- Repair the (K66) P/S Signal circuit for high resistance.
- Perform the PCM Verification Test.Powertrain Verification Test




4. (Z988) GROUND CIRCUIT OPEN OR HIGH RESISTANCE
Turn the ignition off.
Using a 12 volt test light connected to 12 volts, check the (Z988) Ground circuit in the Power Steering Switch harness connector.

NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.

Is the test light illuminated and bright?

Yes


- Go to 5


No


- Repair the (Z988) Ground circuit for an open circuit or high resistance.
- Perform the PCM Verification Test.Powertrain Verification Test




5. POWERTRAIN CONTROL MODULE (PCM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Power Steering Switch and the Powertrain Control Module (PCM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Search for any Technical Service Bulletins that may apply.
Were any problems found?

Yes


- Repair as necessary.
- Perform the PCM Verification Test.Powertrain Verification Test


No


- Replace and program the Powertrain Control Module (PCM).
- Perform the PCM Verification Test.Powertrain Verification Test