DF 300, intermittent 2-4, 2-5, 3-6 codes with hiccup

Old 06-16-2020, 09:02 AM
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Default DF 300, intermittent 2-4, 2-5, 3-6 codes with hiccup

2017 DF 300 with 400 hours. No issues until, in March, while getting on plane, motor skipped and threw the 2-4 (CMP) code. Only happened once. Researched and read it could be white wire. Checked white wire at the battery, replaced ring connector.

Motor has run fine since, no codes. Ran it offshore all day last Wednesday, no issues.

Last Friday, out to pull the kids and 5 minutes in motor skips while getting on plane and throws 2-4 code again. Everything else appears fine. Battery voltage reading 12.6. Proceeds to skip occasionally, throwing additional codes 2-5 and 3-6 (O2 sensor), but less frequently over 6 hours on the water.

This sounds like it may be an ECM power / ground issue. Looking for guidance/ feedback on where to start searching. Thanks in advance.
Old 06-19-2020, 01:48 PM
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So for anyone else out there who may have similar problems, I was able to find a few things that were not perfect that I hope will fix this issue. The first was an exposed power feed running from the battery + terminal to the motor.

It seems unlikely this was my issue, but I did cut it out and crimp a new lug connector to the battery switch, only to find the switch completely disintegrated when I removed it, so had to replace that as well. Next, I set upon tracing the Suzuki sub battery wire (infamous white wire). Found this wire was attached to my house battery and NOT my starter battery. The connections at the battery looked good. Traced the wire to the first 30A mini blade fuse. This fuse was corroded and fell apart while removing. Cleaned up the holder connections and replaced the fuse, adding a new back-up to the holder. I kept tracing the wire down into the bilge where it connected into the Suzuki wiring harness. It appears the sub battery wire splits at this point, with one leg going aft to the motor and the other going forward to the helm. The connector at the harness appeared to be corroded on the inside (see pic), so I replaced it with water tight butt connections and made sure to secure the harness up in the bilge out of any water collections. I am hoping the combination of these fixes takes care of my ECM issues, but have yet to sea trial it, because of storms in the area.

The only thing that is puzzling me now is the voltage reading I'm getting at the helm on my Simrad EVO3. The Vsupply gauge reads considerably lower than what my voltmeter is reading at the batteries, and at the helm power bus that supplies the Simrad.

Does anybody know where the Simrad gets it's source for the Vsupply? I would assume from the main power cable. But the power bus is showing 12.8V. The wiring looks good to the Simrad and is less than 3 years old. All connections solid.

Any insight or feedback is greatly appreciated.
Old 06-20-2020, 02:00 AM
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VSupply is measuring the voltage supplied from the boats wiring to the Simrad. Typically supplied from the house battery. Usually there would be + and - busbars behind the dash and they would be fed with heavier wires to the house battery.

So if you have a significant difference between that and voltage at the battery, then there can be a couple of reasons -

- one being that the wiring from house battery up to the dash and back is not up to scratch, and given the other examples of corroded battery cables and switches you found, that would not be surprising at all. Wiring could be too small, or it could be corroded, even the connections to the busbar and fuses could be in poor quality. All would be worth investigating.

- the other being that its not uncommon to see a variation due to the Simrad giving a lower reading than reality - sometimes it happens, and has been reported in the marine electronic section on several occasions. Voltage is of course important but even more so, is amps, so even though you might take a voltage reading at the Simrad plug with a voltmeter, it might look good but it might not stand up under the load taken to drove the Simrad.
Old 06-20-2020, 05:23 AM
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All those issues you found are possible causes to your alarms, all these new motors are voltage sensitive and need good clean power. Hopefully this is solved, good troubleshooting so far.
Old 06-20-2020, 07:48 PM
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Thanks for the input guys. I was able to run the boat today and am happy to report that the Suzuki did not throw a single code after 8 hours on the water.

Regarding the lower voltage reading on the Simrad... I did measure both at the battery and my bus bar at the helm, and both measured exactly the same, so no drop through the wiring from the battery to the helm. I have never had an issue with my Simrad shutting down due to low voltage, so I am just going to assume that the Vsupply reading on the Simrad is not entirely accurate, and move on.

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