I replaced my PAS rack a few weeks ago. All went well and it's nice to not be leaking power steering fluid everywhere. The only issue I"ve noticed is that it's a little harder to turn going into or out of tight spaces like parking spots. It's fine when driving, no issues. I was wondering if this may be a servotronic sensor issue or is the new rack just a little tight at full extension.

 

To read through the servo at the amplifier socket would be between Red and Slate wires servo side , there is a Black ground . 7.5 ohms reference ZF manual

The amplifier gives out a varying voltage

At no speed Red wire will give 2 volts DC to black ground wire

At no speed Slate wire will give 9 volts DC to black ground

There is a speed signal that comes from the left rear wheel sensor but passes through module A and B before getting to the steering amplifier

 

I looked through the ZF manual troubleshooting sheet and it seems like a transducer issue due to "transducer does not close". Either due to contamination of electrical defect. I guess I'll contact Detroit Axle. It's more of an annoyance than anything.
I've looked through other threads with similar issues and there have been different problems that have fixed the issue. But mine was fine until I replaced the rack.

 

The servo amplifier is only as good as the speed signal reaching it

When you spin the rear left tire in the correct direction the 2 wheel sensor wires will read about 1 volt AC at the ABS module

Maybe this should be able to be seen at the amplifier somehow on X color wire

 

Did you clean the electrical connector at the top of the rack? There should also have been a very thin o'ring that had to be put back in place.

 

I did, I noticed some paint may have got on the prongs but I think I got it off. I may try to unplug and plug a few times. I don't recall an oring.

 

If your missing the O - ring a common rubber at the hardware store would do but not last forever

 

Could the system need to be bled? Air in the system could reduce the assist provided by the system.

 

Would the top layer of the reservoir be access air that was circulating and depositing there ?

Brakes are a different story and fluid sealed from top of reservoir from air

 

If the speedometer works, the relevant wheel speed sensor should be OK.

You should be able to test the signals to the rack transducer that Parker provided by connecting your meter to the rack harness connector with long leads for your meter so you can observe the voltages sent to the rack while driving at slow and fast speeds. If the signals look plausible, then the transducer or its electric connector is the likely problem.

If you're not sure you got all the paint off, you can try forcing the bristles of a small brass-bristle brush down into the connector to try to carefully scrub the pins clean, then flush with zero-residue electronic contact cleaner and allow to dry or use compressed air.

It's certainly possible that the transducer in the rebuilt rack is bad.

Cheers,

DOn

 

In rebuilding O - ring pistons there is a thing on original O - ring thickness and replacement O - rings being too thick

Rebuilders responsibility in testing