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01-31-2015, 09:59 PM #1
2000 EFI 225 3.0L Merc SENSOR ALARM on fresh rebuild
OK IM MISSING SOMETHING
scanner shows CYLINDER TEMP WAY WAY WAY out of bounds like 2 million degrees
also shows air temp at like 1.9 million degrees
and TPS voltage only varies from .84 to 1.9 V at throttle idle to full and adjusting changes no voltage
engine came in blown up with broken crank no other history was running when it let go
obviously something is causing the sensor ranges to be WAY WAY OFF
it will work intermitantly and sensors will read 77 degrees on Cyl temp on a 45 degree day and 44 on air temp then spike back to 1.9 million
checked all grounds cleaned connections
all things appear functional when resistance tested,
obviously im missing something unplgging the oil tank, water alarm sensor wire and cyl temp alarm activation wire unhooked sensor alarm is active even with the obvious open circuts open
motor does start and run but without cleared codes not worth the risk to run more thn few seconds has good new water pump and good flow
this has nippendenso electronics not the late 2000/2001 motorola set up so early Digitial style EFI our block was a first gen Opti block but ran old electronics so its in that no mans land for good infoLast edited by 150aintenuff; 01-31-2015 at 10:04 PM.
4-16-2014. 25 years old today... the fishin boat doesnt look to bad for a classic does she
things that were are no longer as they are today...
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01-31-2015, 11:07 PM #2
according to manual it is saying TPS, ATS, CTS, or CPS out of range duh all are out of wack.... now to WHAT would cause all the sensors to be out of range yet still run
4-16-2014. 25 years old today... the fishin boat doesnt look to bad for a classic does she
things that were are no longer as they are today...
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02-01-2015, 12:57 PM #3
Sounds like you lost either the 5V power or transducer ground someplace between the ECU and sensors. The 5V power should be purple with a yellow stripe, and the transducer ground should be black with an orange stripe. You can key up and pull each one of the sensors and check for 5V on the ppl/yel, and if you reference a service manual you can figure out which ECU pin is the transducer ground and check each sensor for continuity back to the ECU pin. Both the 5V and transucer ground get spliced along the way to each sensor, these splices are suspect, especially after twisting the harness out of its normal position to remove it.
If you do find a break between ECU and sensor, keep checking between sensors to see if you can find the break on either +5V (sensor 5V power, ppl/yel) or -5V (transducer ground, blk/org).
Hope this helps, gives you something to check and eliminate, anyway. Good luck!A problem is only a problem when viewed as a problem...
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02-01-2015, 08:16 PM #4
Hydro. I think out right Because even 2 new modules same alarm. Time to de loom the harness. And go wire by wire
4-16-2014. 25 years old today... the fishin boat doesnt look to bad for a classic does she
things that were are no longer as they are today...
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02-01-2015, 08:28 PM #5
I'd probably diagnose before de-looming, it will minimize that process. You might have a chunk 3" long with some splices that are no longer complete, would be my guess, or corrosion or bent pins at one of those 2 ECU +/-5V pins. Check the connections at the ECU to make sure there are no bent pins, and that no harness pins are pushed back in to the socket and not making good contact with the pins.
A problem is only a problem when viewed as a problem...
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02-01-2015, 09:01 PM #6
Connector at ECM is fine. And I have another complete harness from a motor with 40 hrs on it. I can swap monday and then go look atthe. Harness when I care. Right now I'm more worried about getting this one out and debugging a harness when there is more time
4-16-2014. 25 years old today... the fishin boat doesnt look to bad for a classic does she
things that were are no longer as they are today...
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02-01-2015, 09:12 PM #7
I have 2 identical engines so I have all sensors. And modules etc so just want to get this running. And I can deal with the harness and what sensors are actually defective or damaged after my customer gets his engine back and I get paid. But knowing where to look that it's harness vs sensor makes things a lot faster at this second
4-16-2014. 25 years old today... the fishin boat doesnt look to bad for a classic does she
things that were are no longer as they are today...
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02-02-2015, 07:08 AM #8
Highly unlikely that it is the sensors themselves...they all would not crap out at once. Hydro is right, look for some issue common to all the sensor reading high, like a pinched wire that is common to all the sensors like the gound path or power source. Swapping the harness would certainly help isolate it.
Go Time
2003XS GS 225 Promax/ 260 / 280
26 Regulator twin 250 EFI
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02-02-2015, 04:02 PM #9
Considering I've spent a week fighting this thing and not getting any extra out of my customer to fix it. Swap is all I'm willing to do. I'll look through the harness when time allows when I need it to build later
4-16-2014. 25 years old today... the fishin boat doesnt look to bad for a classic does she
things that were are no longer as they are today...
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02-02-2015, 04:49 PM #10
Found it. Harness had a pig tale replaced On TPS and a wire was crossed. Fixed the splice in the loom and no more alarm. Now I can finally run and deliver this thing. Thanks hydro. You were right on with the harness suggestion.
typical northwest open boat with no gauges or alarm prior to my install. So who knows just how long this issue was going on. I'm sure it is what caused the engine failure. (Combine that with an idiot owner who ran a blown up engine until it failed to start vs shutting it down at first sign of problem. So glad I install gauges and alarms and hydro suggested harness or I'd never found this problemLast edited by 150aintenuff; 02-02-2015 at 05:09 PM.
4-16-2014. 25 years old today... the fishin boat doesnt look to bad for a classic does she
things that were are no longer as they are today...
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02-02-2015, 08:11 PM #11
Glad you got to the bottom of it!
A problem is only a problem when viewed as a problem...
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02-02-2015, 09:14 PM #12
Works great. Put about a 90 min break in heat cycle on her. Never missed a beat other than blubbery from the double oil mix it's being fed. But even still. Boat was able to run mid 30's while keeping below 3500 Rpm for first run. Considering it's a low 50 mph boat I'm happy and customer is as well.
4-16-2014. 25 years old today... the fishin boat doesnt look to bad for a classic does she
things that were are no longer as they are today...