Manager Forum

Was brought in with the steering locking up. Put in a rack since it was leaking.

Came back in doing the same thing, but this time it turned on the OnStar..?

On Star will automatically turn on under certain circumstances. There is a recall for on star about improper activation. If you can get information from customer about what happens right before p/s fails it may help. The pressure release valves can stick open and cause the steering to fail. An example would be if the customer yanks the wheel all the way to one side and raises the idle enough this will cause the valve to open to relieve strain. It's designed to close when pressure drops off, sometimes it hangs up and the steering fails.

The owener told me then it has happened in parking lots at low speed. Said it has happened about 3 times since i replaced the rack..

check pump pressure at an idle then with foot on brake in drive. Computer should step up idle to maintain proper pressure. There is a sensor in the p/s line to read pressure and send info to pcm.

Some caddys have tsb for ps pressure line problems If I recall

Put your scanner on and pin the wheel. See if there is an increase in the idle or a call for one. The other issue may be a performance issue. There may be a small vac leak that the pcm can compensate for to a point but can't under a strain. You've got a vehicle that probably is running with the a/c compressor cycling on and off all the time because of climate control. Combine that with low speed and pump strain it's possible the engine is stumbling a bit and not spinning the pump fast enough. I didn't see a tsb about this issue. It may be a pump issue, pressure needs to be checked. Before I do that I would watch the idler through my scanner. Make sure it maintains minimum idle under a strain. I have seen improper fluid cause issues but usually a pump whine. Another issue may be the tensioner for the serpentine belt. Not on this particular vehicle but I've run across it before. Release the tension and see if the tensioner returns with strength. If it returns slowly and not deliberately this may be your issue. Another key point and I know it can be a pain is a road test to duplicate the issue. I really dislike long road tests but they are necessary at times.