DF90 Auto Reset

[McKee8]

I have a 2001 Suzuki DF90 with excellent service throughout the years. Today I experienced a problem: When I turned the key to the "ON" position (not START), I normally hear a long beep as the fuel is primed to the motor, then I start the motor. Now I have an intermittent problem: nothing happens when I turn the key to the ON position, and of course I can't start the motor, or move the trim. I wait a few minutes, something resets automatically, and then it's back to normal. It starts fine, runs fine. But, after a few minutes, it stops again, I wait, then it's normal again. I heard a click when I turned the key to ON, so I removed the motor cover to isolate the next 'click'...it came from a small round module located just above the fuse box. Could that module be the problem, or is that module doing what it is supposed to do initiated from some other problem? Everything shuts down after the click, even the trim function. Intermittent problems are the worst to troubleshoot and fix. I will not take it far from the dock.

[Moonlighter]

McKee, I haven't heard of that issue.

It sounds to me to be most likely an electrical problem, and if you do some research on this site and others you will see plenty of posts where people have had weird problems like that and found the problem in the wiring harness/battery connections. These engines with all their electronics are quite sensitive to voltage supply. One dirty connection, a corroded wire and they will not be happy!

So my suggestion is to start with the simple things. Remove and clean battery connections and check battery cables are not corroded. Give them a gentle flex and any crunchy sounds indicate corrosion inside. A small nick in the insulation.....

Make sure the batteries themselves are well charged and get them load tested to make sure they are up to scratch.

Double check that 'white battery sub-wire, it's really important as it provides power to the ECU. Make sure it is connected to the battery direct or the battery switch.

If that doesn't help, then start on the wiring harness.

Start at one end and work all the way they to the throttle control, open all joins and check for corrosion. Particularly that white wire again!

It's a fair bet the problem could be in the harness, or in the key switch or associated connections.

Good luck. Be methodical and I am sure you will find the issue.

[McKee8]

Good Tip

Thanks for your advice, Moonlighter and Redlowrey! I will certainly follow-up to locate a potential electrical problem, and report back to this forum with results. I believe you guys have hit on the root cause, and I'm eager to say "ah ha, there's the problem", and until then, it will probably happen again.
McKee

[redlowrey]

On those early engines the ignition supply comes from the starter through a short red wire to a terminal block, then through the sixty and thirty amp fuse. From the thirty amp fuse battery voltage will travel through a white wire to the main control relay down to the ignition switch. When you turn the key to on, battery voltage will flow back to the main control relay through a gray wire through the relay coil to earth at the ecu, When this happens the main relay contacts close and battery voltage will travel through another gray wire and supply voltage for you coils fuel pump, injectors ect. The noise you can hear sounds like the main control relay dropping out, when you say your trim doe's not work, it sounds like you have a voltage drop problem between the starter and the main control relay. The problem should be easy to find if you know how to use a multimeter, hope this information helps.