Garmin Autopilot ECU questions

b_arrington

Well-Known Member
GOLD Sponsor
Feb 21, 2007
3,469
Setauket, NY
Boat Info
Back Cove 37
AB Ventus 9VL
Engines
Cummins QSC 8.3 600
I have a Garmin autopilot setup that's having some issues.

The equipment:
  • 8616 plotter
  • GHC 20 autopilot display
  • Reactor 40 autopilot
  • Smartpump v2
  • Shadowdrive
The issue:
  • System worked flawlessly for a 900+ mile trip
  • Recently at dock, when system on it threw multiple and persistent "low ECU voltage" warnings. Boat was on shore power with batteries at nominal voltage and charger working.
  • Rebooted and also had engine running; minimal result. Warnings eventually stopped.
  • This weekend I went to engage the AP and got an error: "ECU not present".
Troubleshooting plans:
  • Check all the power cables to ensure they are not loose.
  • Check the ECU 40A fuse to ensure its not blown
  • Check the voltage for the ECU power cable to ensure its getting 12v at the end of the cable.
  • Check the cables between the CCU and the ECU to make sure they are not loose
  • Check the N2K cable between the CCU and the rest of the N2K network, and ensure there are proper terminators. I kind of discount an N2K issue because other items on the N2K network are working OK.
Any other suggestions or areas to consider for troubleshooting?
 
I have a Garmin autopilot setup that's having some issues.

The equipment:
  • 8616 plotter
  • GHC 20 autopilot display
  • Reactor 40 autopilot
  • Smartpump v2
  • Shadowdrive
The issue:
  • System worked flawlessly for a 900+ mile trip
  • Recently at dock, when system on it threw multiple and persistent "low ECU voltage" warnings. Boat was on shore power with batteries at nominal voltage and charger working.
  • Rebooted and also had engine running; minimal result. Warnings eventually stopped.
  • This weekend I went to engage the AP and got an error: "ECU not present".
Troubleshooting plans:
  • Check all the power cables to ensure they are not loose.
  • Check the ECU 40A fuse to ensure its not blown
  • Check the voltage for the ECU power cable to ensure its getting 12v at the end of the cable.
  • Check the cables between the CCU and the ECU to make sure they are not loose
  • Check the N2K cable between the CCU and the rest of the N2K network, and ensure there are proper terminators. I kind of discount an N2K issue because other items on the N2K network are working OK.
Any other suggestions or areas to consider for troubleshooting?
Brad, I found this at Garmin.com (https://support.garmin.com/en-US/?faq=89SFTnbO1o1y6UhMCiOCc7):
  • ECU Voltage Low - This usually indicates a sagging supply voltage from insufficient supply power or heavy hydraulic loading.
Not sure how to diagnose "heavy hydraulic loading" but I guess it needs to be on your list.
What model of ECU do you have?
 
Brad, I found this at Garmin.com (https://support.garmin.com/en-US/?faq=89SFTnbO1o1y6UhMCiOCc7):
  • ECU Voltage Low - This usually indicates a sagging supply voltage from insufficient supply power or heavy hydraulic loading.
Not sure how to diagnose "heavy hydraulic loading" but I guess it needs to be on your list.
What model of ECU do you have?
This is the info from my unit. It’s a Smartpump v2, and I understand the ECU is built into that unit. Beyond that I don’t know.

upload_2021-6-9_17-17-44.jpeg


I did see that link also. It doesn’t make total sense because the low voltage alarms occurred while sitting at the dock - there should have been zero hydraulic loading let alone heavy loading. I kept checking my batteries to ensure they had good voltage and they did.
 
This is the info from my unit. It’s a Smartpump v2, and I understand the ECU is built into that unit. Beyond that I don’t know.

View attachment 106861

I did see that link also. It doesn’t make total sense because the low voltage alarms occurred while sitting at the dock - there should have been zero hydraulic loading let alone heavy loading. I kept checking my batteries to ensure they had good voltage and they did.
My ECU is separate from the pump, looks like this:
GAR-010-11053-02.jpeg

I think it is closely related to the pump so maybe they figured out how to integrate them. I searched around a little and it seems like pump issues are fairly commonly the cause of your error message. One guy on THT said he had gone through four pumps.
 
I think I found my problem. Checked the voltage at the ECU power cable end and it measured 1.05 v - way low. Tracked the power cable back and found this.

C3DEEEAD-D674-4523-A51A-8238C9698A26.jpeg

There’s a bit of water in the bilge where the power cable was run and the cable was spliced. The two crimp and shrink tubed connections are covered in corrosion.

I’ll make new water proof connections and secure the wire up out of the bilge and hopefully that will solve it.
 
My ECU is separate from the pump, looks like this:
GAR-010-11053-02.jpeg

I think it is closely related to the pump so maybe they figured out how to integrate them. I searched around a little and it seems like pump issues are fairly commonly the cause of your error message. One guy on THT said he had gone through four pumps.
By the way, I confirmed my ECU is integrated withe the pump. It’s basically bolted on the front.
 
Success! Yesterday I cut out the severely corroded connections and replaced with new ones. Used adhesive lobes heat shrink but connections. Then covered with a section of heat shrink tubing since the crimping cut the insulation in the connector. Then hit it with some liquid electric tape for good measure.

Then secured the wires to the stringer with wire tires to keep it out of the way. And lastly, wiped up the dingy water laying against the stringer in the bilge. All nice a clean now.

The autopilot fired right up and I got my rudder indication right away. Feels good to find and solve a problem in short order.
 

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