Do you have a part number?Originally Posted by DewRonInc
Do you have a part number?
8020380 is the 300XS Diagnostic Manual.
Note: The Analog trim wire (brown with white stripe) originates as a bullet connector up near the oil pump. It then routes into the wiring harness and terminates as PIN "K" at the 14-pin keywitch harness connector. That's it.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
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Got it. I'll ohm it out to see if they connect. Why would the PCM care what trim position the outboard is in? The trim sensor wires are hooked directly to it.
The 5VDC supply is understood.
Last edited by L78steve; 05-24-2021 at 09:40 AM.
DIGITAL trim is a SMARTCRAFT feature, and thus MUST be processed through the PCM.
The PCM does have some trim monitoring logic, items such as over-trim and rapid sensor input changes (which can indicate an underwater strike) may result in Engine Guardian.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Makes perfect sense. My only hope is to get the converter to work. Will advise.
OK, Here are the results. I installed the 837 converter. The instruction sheet has directions for sensor wiring that may or may not match up to the converter. Wired up according to the schematic for my engine. Gauge went to down reading, But didn't start moving up until the trim was beyond usable range. So I pulled the sensor and advanced it one hex notch. The gauge now starts at 1/4 and usable trim limit reads at 1/2 on the gauge. So at least now I can index my optimal trim position. Not perfect but better than nothing. Keep in mind my set-up is the single ram trim. The converters intended use is for the 3 ram set-up.
Just need to test run to see if the PCM accepts the new input.
Thank you Don for the help. See you at the end of the season for some fuel system maintenance.
Thanks for the update. Don't recall whether that calibration would have problems with an input that high... if not, you've got something you can reference (at least).
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
OK, Some overdue update with this experiment. It seems like this idea I had may be causing a problem with the PCM. Up to 60 MPH everything is normal. At 65 MPH the engine shuts down to idle. No codes or warning buzzer. Does this situation sound like a trim input issue?
Absolutely no experience with this particular scenario... but fairly simple to determine by simply reverting everything back to the DESIGNED configuration and see if the problem occurs.
Be VERY careful, because any cross-feeds of the engine's 5V reference "H-Bridge" to 12V devices can and does cause serious damage to the PCM (it is often too late when you start noticing running problems, etc).
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Thanks, I'll give that a try.
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