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Introduction and help please! Mercruiser Fault codes?

G

Grinno

New member
Hi all,

I am new here, I live in Australia, and have a 24' Larson Cabrio sports boat and a 21' Millenium ski boat with a 200hp Merc as well.

We are having some issues with fault codes and was hoping within the wealth of knowledge someone would be able to help.

The engine is a mercruiser 5.0 MPI, approx 2007/08 model.
Codes are: PITOT CKT LO
FUEL LVL HI
TRIM CRT HI
LIMITOR FAULT
BLK PIS CRT LO

It beeps approx twice per minute as well, I have done some searching and not been able to find all the codes but on some, Any help appreciated.
 
The beeps indicate your 555 ECU has entered "Guardian mode"...the first three codes will NOT trigger guardian mode. There is more than one LIMIT parameter listed in the manual...any info from the scan tool which limitor is faulting? as far as the last code, if you typoed, it could be BLocK PSI...if it is, this can induce the guardian mode. You should be able to verify this by extracting the freeze frame data with a scan tool...

Unfortunately, neither of the 555 ECU manuals provides significant detail...i would suspect that the real issue is in the sea water pump monitoring circuit and it has faulted to a HI or LO condition....you can verify this with the data monitor mode of the scan tool..
 
makomark said:
The beeps indicate your 555 ECU has entered "Guardian mode"...the first three codes will NOT trigger guardian mode. There is more than one LIMIT parameter listed in the manual...any info from the scan tool which limitor is faulting? as far as the last code, if you typoed, it could be BLocK PSI...if it is, this can induce the guardian mode. You should be able to verify this by extracting the freeze frame data with a scan tool...

Unfortunately, neither of the 555 ECU manuals provides significant detail...i would suspect that the real issue is in the sea water pump monitoring circuit and it has faulted to a HI or LO condition....you can verify this with the data monitor mode of the scan tool..
Click to expand...

Thanks for your advice, will have another look at it.
 
As makomark suggested, that must be fault #37; BLK PSI CKT LO.
The manual suggests that the pressure sensor circuit is open, and to check the wiring and the sensor.
This is the pressue sensor on the sea water inlet from the drive.
The sensor is located at the aft end of the block, on top of the bellhousing, screwed into the PS cooler.
If the sensor and wiring all check out, I would suspect the pump inpeller is dying, or the sea water system is blocked somehow.
If you have not changed the pump impeller within the last few years, or more than 100 hours, I would do that first. Alpha Gen II leg, right?

Rod
 
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