2005 HPDI Engine Stop Lanyard issue on YDS

[seahunt1]

Appreciate anyone who can help with a troubleshooting ****plan regarding my 2005 HPDI that is having a strange issue after many years of great operation. During summer commissioning (fuel filters change out, spark plugs, large anodes, etc.) for the first time the engine would crank but not start. I drain the VST before the winter and when I turned the key to the on position noticed that the electric fuel pump in the VST wasn't turning on. Remote Buzzer alarms after trying to start the engine when the key goes back to the on position. Hooked up and tried to diagnose on YDS, with the key in the on position, the "Engine Monitor" menu showed engine lanyard stop switch ON. Replaced the remote control switch panel, checked the ECM relay and injector driver relay, some fuses, oil level sensor, fuel cup water sensor, electric fuel pump relay, remote control switch panel wiring harness and all seemed to check out. Eventually after testing and jiggering when I noticed YDS showing the stop lanyard switch as OFF I turned the keyswitch to the ON position, VST electric fuel pump immediately worked and engine started and sounded great for a few minutes. From what I gathered YDS showing stop engine lanyard switch OFF is the normal running operation (open circuit/OFF). Strange part is won't run again and when checking the "Diagnose" section in YDS it says lanyard switch OFF, but in "Engine Monitor" section of YDS it says lanyard switch ON. Anyone ever encounter this before. Didn't test the thermoswitches yet but could that impact the kill switch circuit and cause a incorrect reading on YDS? Any help is greatly appreciated.

Thanks

[fairdeal]

when checking the "Diagnose" section in YDS it says lanyard switch OFF, but in "Engine Monitor" section of YDS it says lanyard switch ON. Anyone ever encounter this before.

I have not encountered it,
can't understand or explain it.

But it would certainly seem,
if "ON" is reported in the "Engine Monitor"
the engine is not going to start.


'typically' when the lanyard IS pulled,
if the starter motor is used to crank the engine,
the ECM will make the audible alarm sound -
is that happening?

[seahunt1]

Correct, audible alarm after cranking the engine. I checked the lanyard kill switch and remote control harness all the way back to the ECM and they are not showing continuity so would think the kill switch and it's circuit white to ground are good. Randomly during troubleshooting YDS showed me the kill switch was OFF and which the electric fuel pump ran and the engine fired right up. It ran for a few minutes with no issues but it cut off and kill witch turned back on per YDS. In reading multiple old posts it sounds like it's very rare for the ECU to have issue but here's a photo of the back. Not sure if this is normal wear and tear.

[fairdeal]

here's a photo of the back. Not sure if this is normal wear and tear.

I have no idea why Mitsubishi (who makes the ECMs) adds kitty litter to the potting epoxy,
but yes, that is the normal appearance.

I believe, although I haven't looked for a schematic for your engine,
the white wire comes off a pin on the ECM and goes directly to the helm
then the stop signal occurs when the white wire is grounded.

If the grounding isn't occurring via the killswitch,
or the ignition switch,
or in some (intermittant!) "short" to ground somewhere in the wiring,
then would seem an internal problem in the ECM.

None of those scenarios seem likely, IMO
But there you are nonetheless.

[seahunt1]

Thanks for your help. Really didn't plan on getting a new ECM but if it's truly the culprit guess might have to. I also might not have the full software version of YDS. Noticed in the manual something about special functions but I don't have that option in the program. Is there any ECM reset option via the program that might work that a Yamaha mechanic could do?

So Just in case I missed something FYI, did the following tests on the kill switch circuit.

Continuity Test at 8 pin remote control switch panel harness connector located in engine to test remote harness ignition switch and kill switch, 8 pin harness disconnected at engine (connector near throttle link rods):

Test on white and black pins
Ignition switch off - continuity
Ignition switch on - no continuity
Ignition switch starting position - no continuity
Ignition switch on & lanyard pulled - continuity

Continuity Test at 8 pin remote control switch panel harness connector located in engine, 8 pin harness disconnected at engine and disconnected at ECM:

No continuity on white & black