Thanks Red. On the Nissan unit, the wiring/circuit board was all part of the sealed pump unit. I would have had to do a major disassembly to try and figure out what would make the pump run

I figured I'd give an update. My steering has been getting more flakey, having more trouble keeping up with fast wheel movements in parking lots, lately. After letting it sit for about a week, the hydroboost started taking a second before boosting, and kicking the pedal back. It has got a little better with driving, but there is definitely something wrong.

To eliminate the wiring possibility, I ran 1g welding cable from the battery to a power stud next to the pump, with a 100A breaker inline right on top of the battery. I rewired the pump with 4g cable soldered directly to the connectors in the plug. It's all very nice looking now, but didn't make a noticeable difference.

My steering box has started to leak, which I think is contributing to the problem, but I think the root issue is that the pump just doesn't have enough flow. At least in default mode. It's hard to say if it's running at full volume, or waiting for something from the CAN bus to tell it to spool up.

So now I'm trying to decide what to do. I know the pump will run the hydroboost just fine alone, so I'm considering replacing my leaking steering box with a manual box, and installing a full electric steering assist unit from a Saturn Vue. There is plenty of room between the steering column and the firewall to splice it right inline, and the Vue unit is already beginning to be used successfully in the muscle car community.

I don't really want to keep the hydraulic pump if I go this route, so I'd probably eventually go to one of the electric boosted master cylinders like this. They're supposed to work very well, but are expensive.

sorry to hear about the problems. If you go manual steering I would spring the extra $ and get new rebuilt I think Cardone 27-5000. I got a used manual box from ebay and it is used up. the rebuilt boxes are close to $200 and a core charge, and they use a different pitman arm on the jeeps than the PS pitman arms