Simrad HLD2000 Autopilot

We started having problems with our Simrad Autopilot several months ago.  We were receiving a Rudder Response Feedback Failure on the Simrad AP22 display.  At first it would only happen while sailing in strong winds, but then it started happening in light winds and even when we were motoring.  We did some research online and also checked out the manual, which suggested looking at all of the wiring, connections and junction box.  

During our investigation, we discovered that the autopilot pump on the hydraulic linear drive was extremely corroded on the bottom.  We also found steering fluid on the hydraulic arm and around the autopilot area. We disconnected the hydraulic linear drive (Simrad HLD2000 MK2) from the brains (Simrad J300x), and brought the unit out into the cockpit for a closer look.  With the amount of corrosion, we decided to have the unit tested at our local Simrad repair shop. They said the unit tested good "to factory specs" after refilling with steering fluid. They suggested that we clean up the unit and reinstall it.

We took the pump off the unit to clean the rust and then repainted it. We put the unit back together again and then put it back in to the boat. This required some major "boat yoga" with Geralyn helping through the quarter berth and me on top of the batteries. We got the unit connected and bolted down and then started testing at the dock.  The test failed – the linear drive was not working.  How frustrating!  It was such a difficult job to remove the unit and put it back in.  We noticed that when we powered up the autopilot, the clutch would engage and take over the wheel by locking it.  So we assumed the clutch was working, but the pump wasn't.

We decided to disconnect the pump leads from the J300X and do some testing with a volt meter.  When we connected the volt meter to the J300X leads and pressed the buttons on the autopilot to turn to port or starboard, we got a spike in volts. This told us that the J300X was sending voltage to the pump, but the pump wasn't activating. Feeling pretty energized from the troubleshooting, we took the whole unit out again and disconnected the pump. We connected a couple of leads to the starter battery and tried to get the pump to energize straight from the starter battery. Nothing!  We opened up the pump to make sure the wires were connected on the brushes.  We noticed that one of the brushes was stuck.  The next day we took the pump to the Simrad repair shop to see if they could fix the problem. They called later to let us know that one of the brushes wasn't making contact and that they were able to fix it.  We tested the pump one more time on the boat before installing it on the linear drive – it worked!  After a few stretches, we reinstalled the unit in the boat.  We then did the dock side test again and it went well.  Phew!  We weren’t able to do the sea trial test that day, but will complete that to make sure everything is running smoothly.  Fingers crossed we’ve fixed the problem that was causing the error in the first place.