Navpilot 520 o/b "Rudder Driver Error"



The problem I’m facing is my Furuno Navpilot 520 will complete dockside setup and rudder test successfully, but continually get “rudder drive error” when attempting to autocalibrate or use the autopilot in any conditions other than tolling speed in calm seas.

The AP system is a Navpilot 520 O/B using a Furuno HRP11-12 pump.
The boat is a 2120 Parker Pilothouse with Yamaha F225 outboard.
Steering is Seastar/Teleflex hydraulic helm (I believe the Seastar 2.0cu model HH5273)
and the steering cylinder is SeaStar/Teleflex HC53xx.

After the dockside setup, the rudder test usually reports deadband ~0.9deg, and PWM
duty cycle usually comes in at 55%, sometimes 60% and occasionally 50%. (according to installation manual, 50%-90% is within spec.) I don’t recall the rate of turn reported, but believe it was usually somewhere between 4.1-5deg/sec.

I had a chance to run the boat last weekend and found what might be an interesting
data point:
I met “rudder drive error” even when using the jog buttons to steer the boat but only in the starboard direction. At low speed (<5kts), I would not see any problems, but when the system was under load from the boat moving faster (~12kts in this case), the pump would fail to operate but only when trying to move rudder starboard.
If I pushed port jog, I could hear the pump operate and rudder would move port. If I pressed starboard jog, the arrow indicator on the LCD would indicate rudder command, but I could not hear the pump start.
If I continued to hold the starboard jog key down long enough, the system would report “rudder drive error”.

Does failure only under load and only in one direction sound consistent with any kind of pump failure you’ve seen before? Do you know if this suggests that I have a bad pump, or that the HRP11 is oversized/stalling and I need to drop down to the HRP05?

Thanks much in advance for your help!
Your problem is a puzzle for sure.
I would start by having the pilot software for both the processor and display updated to the newest version. Then I would reset everything up from scratch. (Dockside setup, rudder test, sea trail) and see what happens.
Performed full factory reset and re-calibration. Rudder diagnostics passed but
sea trial autocalibration still fails with "Rudder Drive Error".
Screen shots with SW revisions of each component are listed below.
I could reproduce a Rudder Drive Error failure using just the jog keys, so I don't expect this to be a SW control loop issue. Are there any newer SW revisions to the processor unit that have pump PWM drive SW fixes that might address what I'm seeing?

I do not believe it is a HW related PWM drive issue because I was provided a 2nd power board to try by a local Furnuno service rep. and after installing the 2nd power board the system still gives the error.

I have checked and purged the hydraulics multiple times, the Teleflex smartstick is reporting good, consistent rudder positions during rudder test and when I move the helm manually.
It really seems like the pump itself is the only thing left but the local Furuno rep I worked with had me remove and send them the pump for testing. They said it tested ok, but I'm wondering if bench testing really tested it for failure under load and there could still be a problem with it. Is there a way I can try exchanging the pump without having to buy a 2nd one just to test this? If not the pump, what else can I try?

heading sensor

processor unit

control unit

startup diag results

rudder diagnostics results
yes, just this one control head (FAP-5021), no additional or optional remote control units are installed.
Without knowing your steering cyl(s) size it is hard to say if the pump is correct for your system but based on the rudder test results it sounds fine. Please check jumper JP1 on your processor and ensure that it is on pins 1-2 and not 3-4. If it is correct, next I would check the wiring from the power system to the processor, and then the processor to the pump. Since these carry a lot of current, you should have beefy wires. If your wire gage is too small it will starve your pump when it gets under load and needs more current. The longer the wire run is the larger the wire gage must be. If that isn't your problem; then I would say you have a power board issue in the pilot processor or your pump has an issue.
Hi Johnny Electron, thanks for the inputs so far. Here are some additional details:

Helm pump is Seastar 2.0cu model HH5273)
Steering cylinder is BayStar/SeaStar/Hynautic Outboard Cylinders
HC5345 OUTBOARD .75 (19.0) 8 (203) 8.34 (136.6)

HoH using the manual helm is 5 turns whether I turn from full prt to full stb, or full stb to full prt.
According to a support person I contacted at accu-steer, the HRP11-12 outputs approx. 1.1, which should give about 8 seconds H-O-H. He also said dropping down to the HRP05 would give about 16seconds and might be a little too slow.

I verified the jumper settings on processor module: JP1 is set to pins 1-2 for no additional controller, and JP2 is also set to pins 1-2 for linear smart stick.

Wiring from battery to main terminal block is about 12-14ft 4AWG,
+ 1ft 6AWG from terminal block to fuse block,
+ 2ft 10AWG from fuse block to Autopilot processor unit.

Wiring from Autopilot processor unit to pump is about 6-8ft of 10AWG.
All wire is ancor marine grade.

I think an issue with the power board has been ruled out since I was given a replacement power board (known good board still in factory anti-static package) and after intalling it, the symptoms are the same.
The HC5345 steering cyl rates 8.34 cubic in.
If you only have one of these cylinders, then the HRP11-12 pump would be appropriate.

Your gage of power wires seem more than enough if not larger than you need.
If they don't have corrosion (causing power loss), you should be good there.

With the new power board in the processor and new software; It is looking more and more like some sort of issue with pump or binding of the hydraulic system under load. Like you I wonder if the pump was tested under load. Who tested the pump?
Hi Johnny,
Sent you a PM with details of the local support rep I dealt with.
Took the boat out again and the problem is still confirmed to be rudder drive error when the AP attempts to make course corrections to STBD. Ran for a couple hrs trolling ~8kts/2500RPM in calm offshore seas. Observed more than a dozen failures every 5-10min, all occurring when the display showed a rudder command to STBD and the pump failing to start. It appeared also that when course corrections to STBD didn't fail, there was still a greater lag time from rudder command indication, to rudder position change.

Performed the following additional tests:
1) swapped the PWM A/B pump drive output lines (and re-performed the dockside calibration) to see if the failure would change from STBD to PORT; possibly indicating the problem was with the AP PWM output. Even with the A/B lines swapped, the problem remained to STBD.
2) Adjusted the zinc trim tab located just behind the prop on the lower unit to 0degrees offset. Original position was ~10degrees STBD to compensate for prop torque.
Result was the steering at 8kts noticeably more difficult to port than stbd which was expected. I could turn to STBD using the helm wheel with 1 finger, while the effort to PORT required one or two hands on the wheel. Even with the minimal effort to steer manually to STBD, the pump failed to steer to STBD.

It really, really looks like a problem isolated to the pump. Is this a possible symptom of a pump issue? Maybe a bad internal valve or something with the pump motor that's affecting operation only in one direction? (and happens only when there's some load in the hydraulic system introduced when the boat is underway)

Hydraulic line run, 8' from helm to pump with 3 bends: 1 to stbd, 2nd to aft, 3rd down to pump:

closeup view of helm T-fittings:

closeup view of pump:
Note - in the closeup picture of the pump, just past the top left edge shown in the picture, the small gauge wire leads from the pump are spliced to 6-8ft of 10AWG to make the run to the PWM output terminals on AP processor.

Also, in the first picture, the furuno message board is cropping the width so you don't see the full view. If you clock on the picture, it should hopefully take you to the full frame view on photobucket. When the boat is on the trailer and tongue jack raised fully up, the hydraulic lines from motor and pump all rise on the way to the helm. Theoretically, any air in the system should eventually rise to the helm pump allowing me to open the filler valve, release the air, and top off the fluid.
I am sure this can be resolved and agree that the pump is looking more and more like the issue.

We have someone who will contact you today at the phone number you PM'd me.