1998 Ranger 2.5 L | PS Pump or PS Pump Pressure Switch | RPM Drop

[sahasranshu]

Hi All,
I understand typically power steering pumps in Fords of that era whine in general and to my understanding the pressure sensor/switch works by increasing engine RPM during demand.

When I make sharp turns when parking, the pump whines very badly and it decreases the RPM of the engine and sometimes even stalls the engine.

In an ideal situation, the pressure switch should trigger and command the ECM to increase the engine RPM but that doesn't happen in my case. I wonder if the PS Pump has gone bad or PS Pump switch is bad.

Can you please help me figure out if the pump is bad in my situation OR the pressure switch?

 

[Curious Hound]

One thing you could do is unplug the harness from the pressure switch. Make a jumper wire to bridge from one contact to the other on the harness plug. That would simulate the switch being closed by high pressure. Then see if the engine still tries to die when you turn the wheel hard. If not, the switch is bad. If it does, then pump is bad or something else is preventing the pcm from maintaining proper engine rom.

 

[sahasranshu]

One thing you could do is unplug the harness from the pressure switch. Make a jumper wire to bridge from one contact to the other on the harness plug. That would simulate the switch being closed by high pressure. Then see if the engine still tries to die when you turn the wheel hard. If not, the switch is bad. If it does, then pump is bad or something else is preventing the pcm from maintaining proper engine rom.

Thanks for suggestion.
Today I tried the other way, I just disconnected the wiring harness to keep the circuit open and compared the RPMs without the pressure switch connected vs with the pressure switch and did hard steer.

I didn't see any noticeable difference in RPMs which made me think the switch isn't working as expected.
No DTC/CEL though.

Secondly, I noticed that the high-pressure hose is loose, meaning I was able to rotate the hose by hand.
(No visible oil leaks though)

I would try the way you suggested by closing the circuit and if I see that RPM is getting compensated by an increase then I think replacing the switch and changing the nylon oil ring would solve the issue.

 

[Curious Hound]

Today I tried the other way, I just disconnected the wiring harness to keep the circuit open and compared the RPMs without the pressure switch connected vs with the pressure switch and did hard steer.

I didn't see any noticeable difference in RPMs which made me think the switch isn't working as expected.

All that did was prove that low pressure doesn't change the rpms. Thats what we expect. The switch is there to do the opposite. When pressure rises due to the force needed to steering, the switch should close and tell the pcm to increase fuel/air to the engine. That's wht I recommend the jumper, which simulates the switch being closed.

 

[sahasranshu]

All that did was prove that low pressure doesn't change the rpms. Thats what we expect. The switch is there to do the opposite. When pressure rises due to the force needed to steering, the switch should close and tell the pcm to increase fuel/air to the engine. That's wht I recommend the jumper, which simulates the switch being closed.

Thanks Again ! much appreciated.