Like many here, I have been working through a laundry list of small issues on my '98 cabrio. I have managed to get the wiring fixed at the trunk hinge point, and had to replace the trunk lock assembly to clear all the electrical codes. After doing this, we found that my hydraulic pump is working, but not creating enough pressure to raise the toneau cover.

Anyone have any suggestions on something that can be done other than replacing the pump, which is more money than I really want to get into.

 

How did you pressure check the pump? I have purchased a replacement hydraulic unit, motor, pump, etc from a salvage yard for $100. Much cheaper than Audi at about $2400. That's an option.Expect to spend some time tracking one down. I have my doubts that the hydraulic portion of the pump is the problem without knowing how it was pressure checked.

 

Well,

Basically, it is simply a matter of now that the electrical is fixed, and throwing off no codes, you can hear the hydraulic pump working, and everything is trying to work, but is very slow and not powerful enough to move all the components.

I have tracked down a former Audi dealer tech in the area who has opened his own shop, and he tells me that it is possible that the fluid has thickened over time, or that there is air in the lines. I am going to take the car to him to look at. I hope it something simple like that.

 

I'd wager that the electric motor is your problem then. The pump is a gear pump - pretty hard to break that. Thick fluid? Maybe. The weak link in the motor is the brushes and they are not an easily serviced item due to the way they are mounted in the motor. I cleaned mine off and cleaned out the commutator groves (the groves on the contact area on the armature) and the motor worked fine after that. Good luck.