1997 Sport Nautique - RED warning light ON!!!

[scubaguyjohn]

As soon as the engine starts, the huge red warning light in the center of the dash comes on -- in the manual it says this is an early warning indicator for either high temperature (water???) or low oil pressure (gee, that's a big help correct craft) -- This light is impossible to see in bright sun light making it pretty useless :evil: , I ran the boat for at least 30 minutes with it on...however, both water temp and oil pressure guages appear to be reading acceptable levels -- oil pressure is 40psi at idle (doesn't move much with higher revs) and water temp is not over 140 when warmed up...

However, since the warning light comes on immediately even when the engine is cold, I wonder if it could be due to low tranny oil level (appears to be down a quart) ..

The engine has about 220 total hours on it and is the PCM Engine Model PLL TBI 5.7L 275Hp (I've been told its a GM ) anybody know where I could get a more detailed manual online?

...I'd also like to know how to check the tranny filter screen...the last time this engine was serviced ... the knuckleheads left the fliter screen out of the sherwood in-line filter so that may or may not have contributed to what the problem is.

Does anybody know exactly what that "idiot" light measures and where the sensors are located??? THat's probably the biggest question I have!

I've pulled all the sensor leads I could find and none turn it off...disconnected the battery too...I can only find an oil sending sensor near the oil filter but no oil switch...is there one? Would a tranny pressure switch feed it too? I would imagine that the water temp switch and the oil pressure switches are what "feeds" this idiot light but I can't find any others to track...a bad ground could also be the problem but saw nothing obvious...HELP!
Thanks for any help you can give...great forums...John.`

[skinautique]

John,
Only two things trigger that light. The temp sensor or the oil pressure sensor. An easy test is to run the boat and disconnect the temp sensor. If the light goes out, it is the temp sensor. If the light stays on, it is the oil pressure sensor. I would top off the trans fluid too. It has nothing to do with the check engine light though. Check your tranny fluid when it is warm.

[scubaguyjohn]

Thanks...I believe I did that ... I pulled the temp sensor prior to starting the boat as opposed to when it was running and the light remained on...does that make a difference? do you know if on my engine there is only an oil pressure sensor vs other engines which have an oil pressure sensor and an oil pressure switch? Would the reverse work ... pull the oil pressure sensor line and if the light stays on its the temp sensor? John.

[skinautique]

Yes the reverse method would work. If there are two wires on it though, make sure they stay together (touching each other). Not so sure about a pressure switch. Someone else on the board might be able to answer that.

[scubaguyjohn]

Anybody know where the oil pressure switch is on my engine??? I found the oil pressure send unit to the left of the oil filter but no switch...yet...help please.

[scubaguyjohn]

OK - HERE'S THE ANSWER!!! It turns out that the oil pressure switch (near the distributor) is leaking oil...the oil probably filled the switch and caused it to turn on the idiot light...the idiot light resets simply by removing the wire from the switch so I know that is the cause...apparently, leaking switches are common...thanks for your help!