What is power steering pump switch?

CAUTION: While repairing the power steering system, care should be taken to prevent the entry of contaminants or premature failure of the power steering components may result.

1. With the vehicle in NEUTRAL, position it on a hoist. For additional information, refer to Section 100-02 .

1. Using a suitable suction device, siphon the power steering fluid from the power steering fluid reservoir.

1. Remove the RH inner fender splash shield. For additional information, refer to Section 501-02 .

1. Using the special tool, disengage the power steering pump belt from the power steering pump pulley and position it aside.
   • Install the removal tool between the belt and the pulley and turn the crankshaft bolt clockwise to disengage the belt.

1. Remove the 4 bolts and position the driveshaft aside.

1. Using a suitable jack, support the rear of the subframe.

1. Remove the 2 nuts, 4 bolts and the subframe support brackets.

1. Remove the 2 middle subframe nuts.

1. Lower the rear of the subframe.

1. Release the clamp and disconnect the power steering supply hose from the power steering pump.

1. Disconnect the power steering pressure (PSP) switch electrical connector.

1. Remove the power steering pressure line fitting banjo bolt and disconnect the line from the power steering pump.
   • Discard the 2 seals.

1. Remove the 3 power steering pump bolts and the power steering pump. This is a job best left to a qualified repair shop !

I would avoid that entire dilemma by just taking out the whole ps pump and replacing the pulley then, seems like a lot of work but it's worth it cuz the radiator removal is way more involved and more likely to cause problems with antifreeze leaks, also you probably only have to tilt the PS pump to get the pulley off so I would not disconnect the power steering hoses until I absolutely had to

code po551 refers to power steering pressure(PSP) sensor/ switch--range /performance problem===causes --PS system--PSP sensor/switch
Have the power steering pressure checked as it may be a pump problem or just the sensor/switch.. Check the reservoir level as it may be lacking fluid.

From your picture it looks like a power steering pressure switch (PSP)

YOU WILL FIND THE SWITCH IF YOU FOLLOW THE HOSES COMING OFF YOUR POWER STEERING PUMP .THE SWITCH WILL HAVE 2 WIRES COMING OUT OF IT.

First error code
P1650 - Power Steering Pressure (PSP) Switch Malfunction In Key On,
Engine Off Self-Test, this DTC indicates the PSP input to the PCM is
high. In Key On, Engine Running Self-Test, this DTC indicates that the
PSP input did not change state. Steering wheel must be turned during Key
On, Engine Running Self-Test
PSP switch/shorting bar damaged
SIG RTN circuit open
PSP circuit open or shorted to SIGRTN
PCM damaged."

P1703 - Brake Switch Out Of Self Test RangeP1780 - Transmission Control Switch Out of Self-Test Range

Pretty much sounds as if the drive belt has come off the engine. When that happens, your power steering pump won't turn (hard steering), check gauges or check engine light comes on (because alternator no longer is turning, and engine will overheat (water pump not turning either).
Replace the belt and check all pulleys to make sure none are binding or loose (could be why belt came off other than failure from age...takes a minute to check and avoids problems later)

Hopfully this will be ALL you need Besides Pulley REMOVAL TOOL It can be Rented @ AutoZONE

REMOVAL

1. Remove drive belt.
2. Raise vehicle on hoist. WARNING: TURN AIR SUSPENSION SWITCH (LOCATED IN LUGGAGE COMPARTMENT) OFF TO PREVENT VEHICLE DAMAGE OR PERSONAL INJURY.
3. Remove power steering pressure hose bracket.
4. Disconnect electrical connector at power steering control valve actuator.
   1. Install Steering Pump Pulley Remover T69L-10300-B on the pulley hub. CAUTION: Do not apply in-and-out pressure on the power steering pump shaft. Pressure will damage the internal thrust areas.
   2. Hold the small hex-head and rotate the tool nut counterclockwise to remove the power steering pump pulley.
   3. Disconnect power steering pressure hose at power steering pump and drain fluid into a container.
   4. Disconnect power steering return hose at power steering pump and drain fluid into a container.
   5. Remove four retaining bolts and power steering pump and power steering pump pulley assembly.
   6. Remove power steering pressure switch from pump.
   INSTALLATION
   
   1. Position the power steering pump on the mounting bosses of engine block and install the bolts at the side of the power steering pump. Tighten to 20-30 Nm (15-22 ft. lbs.).
   2. Connect the power steering reservoir pump hose to the power steering pump and reposition the hose clamp to power steering pump inlet fitting.
   3. Replace power steering pressure hose O-ring.
   4. Install the power steering pressure hose to the power steering pump fitting. Tighten the tube nut with a tube nut wrench rather than with an open-end wrench. Tighten to 34-46 Nm (26-33 ft. lbs.). NOTE: Swivel or end play of the power steering pressure hose end is normal and does not indicate a loose fitting.
   5. Place the power steering pump pulley on the power steering pump shaft and install Power Steering Pump Pulley Replacer T91P-3A733-A. The small diameter threads on the tool should be engaged in the power steering pump shaft. CAUTION: Do not apply in and out pressure on the shaft. Pressure will damage the internal rotating group.
   6. Hold the small hex-head and rotate the tool nut clockwise to install the power steering pump pulley on the shaft. CAUTION: Do not apply in and out pressure on the shaft. Pressure will damage the internal rotating group. NOTE: The power steering pump pulley face must be flush within 0.25 mm (0.010 inch) of the end of the pump shaft.
   7. Remove the Power Steering Pump Pulley Replacer T91P-3A733-A.
   8. Remove the shipping tube nut from power steering pump housing prior to installation.
   9. Connect electrical connector to power steering control valve actuator.
   1. Install power steering pressure hose bracket.
   1. Lower the vehicle.
   2. If equipped, turn the air suspension ON.
   3. Install drive belt on the power steering pump pulley.
   4. Fill the power steering pump reservoir with Power Steering Fluid Motorcraft MERCON(r) ATF.

Item Part Number Description 1 - Steering wheel 2 - Steering column 3 - Boot 4 - Tie-rod 5 - Tie-rod end 6 - Steering gear 7 - Steering gear to fluid cooler hose 8 - Fluid cooler 9 - Power steering pressure (PSP) switch 10 - Power steering pump 11 - Fluid supply hose 12 - Fluid reservoir 13 - Pump to steering gear pressure line 14 - Steering gear pinion extension

try replacing the drive belt first to see if the helps first there may not be a PSP switch for this vehicle but you can check with a napa or auto zone store to find out