Hey.. I know there are a ton of these threads .. each one has its own different specific issue and cause. I have a "new" one I think.

Background: Our 88 FC3S Vert has ~40k miles on it and is only driven ~1500 miles a year or so at max, so it's a garage queen,

I pulled it out of the garage last night and everything seemed fine and I left it in the driveway. This morning, we had no power steering. No whining, no noise, no steering initially and then stopping at speed, nothing. The dashboard is working fine, the speedo cable is attached securely to the back of the dash unit, there's plenty of power steering fluid, and the fuse (10A) looks good.

What gives?

The only subtle oddity I noticed was that there was a funny smell when I pulled it out of the garage the night before. I chalked it up to burning the clutch as I reversed it up a steep driveway. Could it have been something else?

 

Check the belt?

 

Definitely … The belt is there, there are no obvious issues looking at the PS pump. All the pulleys feel tight, nothing is loose.

 

Check the PS idler pulley. I once had one freeze up on my S5.

 

Check to see if pump pulley is turning?

 

The steering boost is controlled electronically based on engine speed and steering angle. The ecu provides more steering assistance at low speed and less at higher speed. I would start by checking the connector on the pump and making sure its plugged in and is secure and free of corrosion. We can go from there once you ensure the pully is spinning with engine speed, and that the system has the adequate amount of fluid. The fluid should be automatic transmission fluid.

 

Thanks - I was aware that there is a computer controlled component here, but I am unaware of where the wiring for it is. I did recently have the gauge cluster out, and I definitely had a moment where we put it back and the speedo-cable wasn’t fully attached - we got power steering for a bit and then it cut out. Fixing that resolved the problem.

Regarding the wiring on the PS pump - I will go look. Any suggestions where it is? I did look at the PS pump initially and I didn’t see any obvious wires hooked up to it. It’s definitely full of fluid, I checked that. The belts are definitely spinning the pulley. Are you asking if the rod that the pulley is on is spinning? Or asking me to check something else?

 

I went out and re-started the vehicle .. I swear I had power steering for ~30-60s before it died. I found some of the wires going into the PS pump nothing is disconnected or loose or corroded looking. I hear there is a connection under the steering column somewhere. Any suggestions on where to look for that?

Also - is it possible that I have _too much_ PS fluid in there? Would the pump go into some kind of failsafe in that case?

 

Might be way off base, but the speed sensing power steering began with the S5 while the S4 had just the run of the mill PS.

 

Are you sure you don't have air in the lines? Have you tried bleeding the system to see if that helps your issue?

 

The power steering is electrohydraulic and is a speed sensitive power steering. Fairly advanced for the time period.

 

The S4 still has the speed sensing power steering; the training manual goes into detail about it. They also have a third port on the rack that does something with regard to steering feel, whereas some S5s have a two port rack (not sure the reason for the change).

 

Realize that the '88 Turbo models plus the S5 had it installed, engine rpm or vehicle speed, but wasn't certain if the '88 convertible, or other S4 models had the same system.
In fact, I just put up for sale a 3 port rack from a 10AE, and I had the system on the '88 TII we purchased new, but as stated before, just wasn't certain about the other models. Guess I should have done more research before posting.