Engine warining alarm
 

Boat is a 98 PQ 270 Laser, 502 Mag, OK173445
With key on but before starting the engine sometimes the alarm sounds for the prove out, and sometimes it doesn't. Will probably start with a new buzzer just to know that's good, but hoping someone has a good schematic of the system so I know what all is connected.
Thanks.

Wiring and as Crude stated, the Tan/Blue goes straight to the items. Some manufactures use a timer on the buzzer/horn that delays the sound.

To test, turn ignition ON and wait, this will be the oil pressure switch.
Start the motor, then ground the temp switch on thermostat housing
Next pull both leads off lube bottle and jump the wires together

https://cimg3.ibsrv.net/gimg/www.off...a036785393.jpg

That alarm sounding when you first turn the key on is the low oil pressure alarm going off, since there is no oil pressure till you turn it over.

Griff, with key on and engine off alarm sounds for a few seconds and then quits. I thought that was a prove-out so you knew the alarm was working. That's why I thought there may be something else in system.
AllDodge, thanks for schematic, wasn't sure what all was monitored.. Purple wire is 12v and tan/blue wire recieves ground when there is a problem? Am I correct?

Correct, but could also be the alarm if ground is applied and it doesn't continue to sound

0K173445
This serial number is affected by Service Bulletin MC-1997-020. This service bulletin needs to be addressed. Please complete the required service work regarding this issue.
ENG: 0K173445 45021E8KT MERCRUISER 502MPI BRAVO
This is a Federal Recall for fuel line. Highly suggest it be inspected.
502 MPI Tan/Blue is grounded by the ECM

MerCruiser Service Manual #16 Part # 90-823224--2 Should have what you need.

Would like to add how important a OEM dealer can be. Marine OEM dealers are so important and why a boat owner should bring their boat in once in a while is because exact stuff like this. A recall on a 20 year old boat NEVER done.

If this boat was in my shop the first thing I do is -- Very closely look over the engine to see if its a stock set up, then run the engine serial numbers and go from there. - Also make sure the outdrive gear ratio is correct per app because the used boat market is full of so much mixed match part installs.,

It is unreal how many used boats are jerry rigged these days, they might look good on the outside but once you get crawling around a lot of fugly is going on. . Just saying if one is looking at or bought a used boat lately.

I have never seen it so bad for used boats with so much wrong stuff going on and so much improper installs. .

MUC, is this a safety recall/issue that never expires such as in automotive industry? Do I take my serial number to local dealer to have them run it to see if recall has been done or does it require visual inspection?. I assume must be done by authorized Merc tech?
Thanks all for input.