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Juan

Alarm goes off and it rpms go down momentarily

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I have a 2002 chaparral Signature 260 with a 350 mercruiser 5.7L. After a valve job (I.e. cylinder head cracked and boat had no power), wiring harness replacement, and raw water pump replaced, IAC motor replaced, and a few other things that I lost track of. We keep having an alarm go off and the boat loses speed momentarily. It’s a random alarm, I have not found any pattern and it happens at any point in time. I will say that sometimes it takes a little while until it starts, most times not until we get out of the dock. So when accelerate. After being on a plane for a while it does not happen anymore. 

FYI: I tried disconnecting the drive lube reservoir already. The one other thing I’ll add is that I my oil pressure gauge is broken shows max (80) but when connected to a computer it shows normal levels. 

Any help with this will be appreciated... I’m tired of spending money on this. ($7k+) I’ve had 3 mechanics look at it and they can’t figure it out. 

Thank you !!

 

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21 minutes ago, Juan said:

I have a 2002 chaparral Signature 260 with a 350 mercruiser 5.7L. After a valve job (I.e. cylinder head cracked and boat had no power), wiring harness replacement, and raw water pump replaced, IAC motor replaced, and a few other things that I lost track of. We keep having an alarm go off and the boat loses speed momentarily. It’s a random alarm, I have not found any pattern and it happens at any point in time. I will say that sometimes it takes a little while until it starts, most times not until we get out of the dock. So when accelerate. After being on a plane for a while it does not happen anymore. 

FYI: I tried disconnecting the drive lube reservoir already. The one other thing I’ll add is that I my oil pressure gauge is broken shows max (80) but when connected to a computer it shows normal levels. 

Any help with this will be appreciated... I’m tired of spending money on this. ($7k+) I’ve had 3 mechanics look at it and they can’t figure it out. 

Thank you !!

 

Steady alarm or two beeps per minute?  W

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Steady. One beep and the engine revs down for the length of the beep (1 second beep) 

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I have the same boat.  How many hours on yours?

i recentlybhad the the same issue and it was connection issues with the wire harness.

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537 hours. What do you mean by connection issues with the wire harness? Can you please expand on that? Thank you! 

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6 hours ago, Juan said:

537 hours. What do you mean by connection issues with the wire harness? Can you please expand on that? Thank you! 

As the beep is steady and does send the engine into it's power limiting mode, then the ECM see's the issue as critical, which limits the possibilities quite a bit. Sure, there may be a wiring issue, especially on a 2002 boat, so look for corrosion at all the wire termination points, trans-pac connectors, and gang plugs. Also look at the ECM error code list below focusing on the alarms marked constant. My guess is that your raw water pump is beginning to fail and it's low output pressure trips the low pressure warning sender once in a while. W

Warning System

 

The engine warning system incorporates an audio alarm and, if installed, a SC1000 System Monitor. When the key switch is turned to the ON position, the audio alarm will momentarily activate to test the warning system. The alarm should sound once if the system is operable. This table is a quick guide, showing what warning output will accompany a fault.

 

 

Fault

 

SC1000

Audio Alarm

Available Power

 

Description

 

Cam Sensor

 

Yes

 

2 Bp/min

 

90%

Open or short, engine must be cranking to set this fault code.

ECT CKT HI

Yes

2 Bp/min

90%

Open

ECT CKT LO

Yes

2 Bp/min

90%

Short

ECT Coolant Overheat

 

Yes

 

Constant

 

6-100 %

Engine guardian overheat condition

EST 1-8 Open

Yes

2 Bp/min

NA

Coil harness wire open

EST 1-8 Short

Yes

2 Bp/min

NA

Coil harness wire short

Fuel Injector 1-8 Open

 

Yes

 

2 Bp/min

 

NA

 

Fuel injector wire open

Fuel Injector 1-8 Short

 

Yes

 

2 Bp/min

 

NA

 

Fuel injector wire short

IAC Output

Yes

2 Bp/min

90%

Only with rpm

 

Knock Sensor 1

 

Yes

 

2 Bp/min

 

90%

Alarm sounds for 20 seconds in NEUTRAL and indefinitely in gear.

 

Knock Sensor 2

 

Yes

 

2 Bp/min

 

90%

Alarm sounds for 20 seconds in NEUTRAL and indefinitely in gear.

Low Drive Lube Strategy

 

Yes

 

Steady Bp

 

0-100%

 

Low oil in sterndrive

Low Oil Pressure Strategy

 

Yes

 

Constant

 

0-100%

 

Low oil pressure strategy

MAP Sensor 1 Input High

 

No

 

2 Bp/min

 

90%

Short, no visual on SC1000

MAP Sensor 1 Input Low

 

No

 

2 Bp/min

 

90%

Open, no visual on SC1000

 

MAT Sensor

 

Yes

 

2 Bp/min

 

90%

Open or short in MAT circuit

 

NOTE: If any 5v sensor becomes shorted to ground the engine will not start. If the engine is operating when the short occurs the engine may stop operating and will not start.

 

 

 

Fault

 

SC1000

Audio Alarm

Available Power

 

Description

Oil PSI CKT Hi

Yes

2 Bp/min

90%

Short, defaults to 51.7 psi

Oil PSI CKT Lo

Yes

2 Bp/min

90%

Open, zero oil pressure

Overspeed

Yes

Constant

RPM Limit

Engine over rpm limit

 

Port EMCT CKT Hi

 

Yes

 

2 Bp/min

 

90%

Open, defaults to 32 degrees F (0 degree C)

 

Port EMCT CKT Lo

 

Yes

 

2 Bp/min

 

90%

Short, defaults to 32 degrees F (0 degree C)

 

Port EMCT CKT

Overheat

 

Yes

 

Constant

 

6-100%

Overheat condition, 212 degrees F (100 degrees C) limit

 

Sea Pump PSI Lo

 

Yes

 

Constant

 

6-100%

Low water pressure strategy, defaults to

43.4 psi

Sea Pump CKT Hi

Yes

2 Bp/min

90%

Open

Sea Pump CKT Lo

Yes

2 Bp/min

90%

Short

 

STB EMCT CKT Hi

 

Yes

 

2 Bp/min

 

90%

Open, defaults to 32 degrees F (0 degrees C)

 

STB EMCT CKT Lo

 

Yes

 

2 Bp/min

 

90%

Short, defaults to 32 degrees F (0 degrees C)

 

STB EMCT CKT

Overheat

 

Yes

 

Constant

 

6-100%

Overheat condition, 212 degrees (100 degrees C) limit

Steer CKT Hi

Yes

No

No

Open and short

 

TPS1 CKT Hi

 

Yes

 

2 Bp/min

 

90%

Short, signal to 5v+, engine will not start. Refer to data monitor screen.

TPS1 CKT Lo

Yes

2 Bp/min

90%

Open

TPS 1 Range Hi

Yes

2 Bp/min

90%

Above 4.8v, 994 counts

TPS 1 Range Lo

Yes

2 Bp/min

90%

Below 0.5v, 35 counts

 

Trim CKT Hi

 

Yes

 

No

 

No

Short, high range, visual warning on SC1000 only.

 

Trim CKT Lo

 

Yes

 

No

 

No

Open, low range, visual warning on SC1000 only.

5 VDC PWR Low

Yes

2 Bp/min

varies

Short any 5v+ to ground

 

NOTE: If any 5v sensor becomes shorted to ground the engine will not start. If the engine is operating when the short occurs the engine may stop operating and will not start.

 

 

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21 hours ago, Juan said:

537 hours. What do you mean by connection issues with the wire harness? Can you please expand on that? Thank you! 

The main wire harnesses are notorious apparently for being lose and causing power drops and faults.

With the boat running, wiggle it and see if you get the alarm and the power dump.

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 So very true.

The main multi pin plug connector on the engine is a good first step check. For intermittent problems. While idling & moving in F N R.

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