Tuesday, November 14, 2017

GPS taking a break

GPS Shutting down with Low Engine RPM


This is an intermittent issue that we noticed a few times, it's not a critical issue. The GPS will shut down sometimes when we change gear. The process is: Drop the engine RPM to idle, shift to Neutral, Shift into the other gear, throttle up smoothly. It's taken a while to figure out when the GPS wigs out because we're normally focused on other things when we have to change gear, such as holding for a bridge to open, approaching a dock, or shifting astern in order to slow down because some clown has stopped ahead of us for no apparent reason. Whatever, we finally nailed it down to happening when we shift gears.

Intermittent snags are a pain. I had plenty of experience dealing with that type of thing when servicing Navy Helicopters during my Navy days, but that was 29 years ago. I know the drill, try to repeat the fault several times in order to isolate the actions or events that cause the issue. It could be due to an electrical management problem, but also could be an intermittent wiring issue, perhaps a faulty connection that is suffering vibration when the engine changes down below idle when the lever is moved to select a gear. Hopefully we'll find out which it is this week. There's plenty to do on the boat, so we'll take a break and see what we can find.

Here's what the wiring under the cockpit deck looks like from the back of the Aft Berth uggggg!

As I was moving the wires around to try and figure out what's what, a black wire fell out of the terminal block without any effort. Tracing that wire to it's destination showed that it's the GPS Ground Wire! Bingo!

The terminal block connections were awful, so I undid them and stripped the wires back to ensure I'm not dealing with any damaged wires from the previous screw down point of contact.

After re-working the terminal block connections, removing dead end wires (there seems to too many of them on our boat, I remove them when ever I get the chance).

Neatly ran the wires and secured them with new tie wraps but leaving the fuse holders free just in case we ever need to access the fuses.

All neat and tidy, but also secured so that there's no chance any of the electrical cables can move and get caught up on the steering cables (those wheels in this pic) Time to test it all and button it up.

GPS started up and showed 13.6v, Echo Depth sounder is working, Radar - Working, AIS - Working, Wind Instrument display - working, Auto Pilot - Working - Looking good. Button it back up and do some cleaning of the aft berth while I'm in there.

We won't know till the next time out if we have cured the problem, but if I were the betting type, then I would put money on it. (not too much!)

See you on the water.

Paul