Alarm Buzzer Chirping

[Ken Krawford]

I've noticed recently that my temp/oil pressure alarm buzzer has developed an intermittent "chirp" when motoring at higher RPM's (2500-2700}.  It is an off/on phenomenon and goes away if I lower the speed to the 2300RPM range or less.  My oil and coolant levels are ok as is the connection on the oil pressure sender.   I haven't pulled the instrument cluster yet to look for a loose connection but wondered if anyone else has experienced this and what they found.  There are several other reports of this on the C350 message but no fixes are posted.

[KWKloeber]

Ken

Do you have an oil pressure gauge - if not you have a low oil pressure switch (not a pressure sender.)

The B series are particularly problematic to troubleshoot the alarm and oftentimes end up nowhere.  IIWMB I'd replace the switch, taking special attention to the connection. It may solve it but would be good insurance anyway.

The Wb harness is untinned, type 2 STIFF SAE, not type 3 flexible tinned marine wire, and vibration can break off one or both switch terminal tabs. It's a known weak point.
So- Suggest you crimp on pigtails of Type 3 wire or carefully secure the harness so there is NO movement possible between the harness leads and the switch terminals.

[Ken Krawford]

Ken there is no oil pressure gauge - just the buzzer.  I'll check out the switch to start with since it's easier to access than the buzzer.  Thanks for the feedback.

[Kyle Ewing]

I had a similar problem a few years ago and traced it to loose wiring at the engine wiring harness.  I tightened all the connectors (I have terminal strips) and have had no chirp since.

[Ken Krawford]

Thanks Kyle.  I'll put that on my list of things to check.

[Ron Hill]

Kyle : You might look at the connection of those spade connectors on the oil pressure switch.
I'm a believer in soldering connecters to insure a good electrical contact.

A thought

[TortolaTim]

Mine only works intermittently. Worked when I had the survey/ sea trial, then quit when I bought the boat.  I took the panel off and cleaned (what I think are the right wires), and then it started working. Intermittently! Sometimes it do, sometimes it don't. I'm going to try to confirm which wires I need to replace, and then just rewire the whole thing with proper tinned marine wire and connectors. I do have the updated harness, but don't know exactly which wires feed the buzzer.

[KWKloeber]

but don't know exactly which wires feed the buzzer.<<<

Tom your alarm and switch on the XP is different than Ken's.  The blue harness wire from the oil switch (above/in behind the starter and exhaust manifold) triggers the alarm.  it completes a ground path to the alarm.  The wiring of behind the panel depends on (1) your panel and (2) whether you have a separate alarm or the circuit board that triggers the combined hi-temp alarm along with the low oil pressure.

-ken