Mariner 115 1997 CDM erratic buzzer amp cutting out

"My 115 Mariner CDM type has a

"My 115 Mariner CDM type has an erratic warn buzzer and engine cut-out.
Happens when cold or hot. All throttle openinings and at any constant throttle position. Some days it does not happen at all.
I bought the motor second-hand and I'm not sure of the service history. The motor has had a powerhead overhaul by pvs owner. The control box (series 2000) is 100% functional.
Full service just been done, plugs, impeller and lubes.
I've been told to isolate the yellow/black wire from the circuits.
Also to check the oil and heat sensors signal leads for false readings. How do I do this?
Motor runs at correct temp, using oil on autolube as needed and tell-tail is strong.

Are there any other tips?

Kind regards!

Benjamin."

Lets start with the rev-limite

Lets start with the rev-limiter unplugged. Find that module and unplug it. There may be tilt limit switch with a black yellow wire as well. CDM's can't be isolated. That would have you down to one cylinder firing if one of those fails the stop diode. If so than replace the one that is firing.

"Hey there!

Thanks for the

"Hey there!

Thanks for the tip.

The weather was foul the passed weekend, we had four day long weekend, spoilt by Autumn rains... So, not watertime...

Anyway, I've located the Rev Limiter device. The BLK/YEL wire has been isolated from the device, hence isolating the temp & oil sensors. There is no trim limit fitted. The temp ClixOn sensor works fine, I've still to check the oil switch.
Should the problem persist, I'll isolate the BLK/YEL to CDM units, failing that I'll inspect the IGN switch or the deadman's switch.
I'll check it out again when the weather is good.

Have a brilliant day!


From a chilly, yet sunny Johannesburg...

Regards!

Benjamin."

"Me... again...

Sorry, forg

"Me... again...

Sorry, forgot to say that the buzzer's sound is erratic. Almost as if there is a loose wire triggering it, not the solid or interrupted sound it should make. Think along the lines of the buzzer being tested on a battery, and the wires are being scratched against the terminals. Not a solid beep, as the warning sounds, the motor cuts out as the buzzer sounds. The whole rig, obviously, jerking in synch with the buzzer sounding and motor cutting out. Sometimes the motor comes to a standstill, other times the motor splutters and runs again, perfectly.
Lastly, the buzzer does not always do the Self Test when the ignition is turned on, should I suspect the IGN switch?
I've yet to test since disconnecting the BLK/YEL wire from Temp/Oil control unit."

Hmmmm... It really should not

Hmmmm... It really should not be possible to have the problem that you do. Unless there is a wire crossed somewhere. The oil control has no blk/yellow wires on it. Only the rev limit. Maybe a poor ground somewhere.

"Hi there...

Thanks for the

"Hi there...

Thanks for the speedy reply!

The wires from oil sender are blue, the cut-out wires are BLK/YEL from the control unit to the rest of the loom. The harness looks in order, short of stripping the loom from the motor. Is there a way to check for a grounded BLK/YEL without a complete strip? Maybe using a multi-meter of sorts? If so, what setting do I use? I have a Fluke 88.
I think my options to check would be the ignition switch or isolating the CDM's from the circuit.
The previous owner removed the neutral start switch, I have subsequently replaced the micro switch with a new one. That circuit runs YEL/RED wires.
Apparently this is done to ensure that the motor can be started in any throttle position when in surf conditions, it seems that motors stall when cold...
Bearing in mind that the control box and motor are not off the same boat, but is 100% compatible.
Would the stator or charging circuit affect the system?

Many thanks!

Benjamin."

"Just use ohms. Unplug everyth

"Just use ohms. Unplug everything with a blk/yel. Wiggle the wires, flip the key on and off. It is easier to sometimes to plug in another control or cheater key if you have one. Try to narrow it down to the control or motor harness first. Than zero in."

"Hey there!

No spare contro

"Hey there!

No spare control or cheater key available to me... I'm in Africa...

Will isolate the two wiring systems, and check it all from there.

Once I have the control box isolated, between which pins do I check for continuity? Or lack thereof? What must key position be? Starting, running or priming? Should I pulse the key or lightly tap the 'box to establish if the ignition switch is faulty? I've been told that these key switches do have a suspect history... The castings has been dated 1988, saw the imprint when I stripped to replace the neutral start switch. Motor is 1997 vintage.
I have a friend that knows these systems backwards, he's out of town presently and it's not always easy to discuss faultfinding over the phone. He has literature on these motors, but there is not much in terms of diagnostics to this effect. He'll give me a diagram of the ignition switch when he's back in town... Only a few week's time tho.

On the motor side of things... Does the BLK/YEL wire only connect between the CDM & Rev Limit units? I can't seem to follow it any further than that.

Thanks for your help so far!

Regards!"

I am not going to remember whi

I am not going to remember which pins either.
Blk/yel only goes to the CDM and limiter. Try the key in every position with the choke on. I have seen key switches do that.

"Good morning from a chilly Jo

"Good morning from a chilly Johannesburg!

Feels like winter is approaching at a healthy pace... I think my water-time is about to be hampered!

I'll scratch around the 'net for the pin configuration, not keen on stripping the 'box again. Might have to anyway to access the ignition switch...

I'll have to hang on until the weekend to check it all.

I'll keep you posted!

Thanks for your help, it's greatly appreciated!

Regards!

Benjamin."