DF140a Rev Lim light in gear at idle

[dlnw98]

Hi all-

Looking for help with an intermittent problem-

I'm the original owner of a four year old DF140a that repowered our 17' Glastron hull. Motor has 75 hrs on it. No NMEA network installed. Original Glastron tach in dash, with supplemental Suzuki warning gauge installed.

Recently, when the motor is placed into forward or reverse idle, I get a Rev Lim light with a three-tone beep. Also during this time, the Tach is inaccurate- indicating well above correct RPM. As I accelerate while in this condition, the tach needle will quickly advance up to roughly 5500rpm indicated, and then something unusual happens- the tach needle drops back down to a normal 3,200 rpm, the Rev Lim light goes out, and I get a quick double-beep. At that point, all indications will remain normal until the next shift from neutral into gear, with the entire process starting again.

Motor runs flawlessly when this occurs.

This appears to be some type of diagnostic mode or failing speed sensor. It is also different from what the OM describes as water in fuel, which should occur only in neutral according to OM.

I'm at a loss, and my local dealer is no help. Any ideas from the Suzuki pro's out there?

Thanks,

Mike

[Nayna32]

I'm going to take a wild stab at this unsual issue.

I think your troll mode system is activating for some reason.
Troll mode is usually activated when the motor is in gear at idle.
Then you push the up or down switch, and it activates.
The rev limit light should flash continously while in troll mode.
If you have a standard tach, the rpms will jump up and will not be acurate,
since the troll mode tach has a secondary scale on it.
When the upper or lower speed limits have been reached it will beep 3 long beeps
After switching the remote back to neutral or increasing actual engine speed
about 3,000 RPMS it will cancel and give you two short beeps.

I'm assuming you do not have the troll mode switch, so either the troll mode wiring is grounding somewhere or the connector that goes to the switch is connected to something grounding it. I found on my setup that the troll mode connector will connect to the interface cable connector. I know you do not have NMEA, but im not sure if there is another similar connector on your setup.

Hope this helps.

[dlnw98]

Henry-

Thank you for an excellent response. I think you figured it out, based upon how my motor was acting. I went back and read my OM with reference to the Troll Mode, and it all makes sense. My dealer couldn't have connected the dots and diagnosed this in a million years with no Troll Mode switch installed...

Next question- where would I find the troll mode switch plug that could be causing the issue? I'm assuming under the console in the harness, close to where a troll mode switch would be mounted. Any idea of what color or shape I am looking for?

Thanks again,

Mike

[Nayna32]

It is a two pin connector, should be somewhat whitish.
The wire colors are a such: White/Yellow and a Black

The engine harness at the console should have three splits:
4 pin connector that goes to the monitor
2 pin connector for the troll switch
1 gray, 1 black, and 1 yellow wires that connects to the tach
and a red/green wire that piggy backs off of the gray wire.

These diagrams in the Service Manual are hard to read!!!!

It appears that one side of the troll switch goes to black (should be ground)
the other side goes to Gray (should be power)
It says that the black wire is for down and the gray is for an up signal.
So it seems that the switch sends either power or ground to the black wire in the two pin harness connector.
The white/yellow wire looks as if it would send a signal to a analog trim gauge. Do you have a trim gauge?

This is how it appears to operate from what I can gather. I would verify this with your dealer first.

My guess is that it is getting a ground signal since it immediately beep three times (limit reached) after putting it in gear at idle. Also, the speed does not increase without moving the throttle lever, so an up signal is not present.

[dlnw98]

Henry-

Thanks again for the help. Will look at it soon; no time to diagnose anything today.

Yes- boat has original Glastron analog trim gauge that works correctly.

I agree that it is probably receiving a sporadic "down rpm" signal. I have never had an RPM increase, and the triple beep occurs immediately as you said.

Will report back when I get a chance to crawl under the console and poke around. I have some experience with auto electrical so your guidance will be most helpful!