Lost my beep

[MickP]

Hello,
Got a 2GM20F which has been working fine for the short time i have had the boat. But last weekend when turning the ignition on, i did not get the low oil pressure alarm beep which disappears when the engine fires. There is a check switch on the panel and i get a beep from the alarm when i click this, so there is not a problem with the speaker. I have checked oil level with the dispstick and this seems fine. I am guessing it is the oil pressure sender but before i change this i thought it would be worth checking using my multimeter.

What test can i do with my multimeter to show that the sender either is definitely is working, or definitely isn't working?

Thanks
Mick

 

[wetass]

Hi Mick,

Just unplug the wires from the sender on the engine and test the resistance between the sender's connector and the block - should be 0 ohms with the engine off, or at least close. The alarm goes out when the oil pressure increases and causes the resistance to go up in the sender. If the sender shows 0, then its probably your wiring.

 

[kloudie1]

Probably a bad or loose connection. Switch is normally closed that is pin is grounded to the body when there is no pressure. Oil pressure around 2 psi opens the circuit. Multimeter check of the oil pressure switch: (cold engine) remove the wire from the center pin of the switch. Check with ohmmeter pin-to-ground.. should be a short, 0 ohms. If open, switch is bad.. put the wire back on and turn on the key (don't crank the engine up) . Measure DC volts from the pin to ground.. should be 0. crank the engine and the voltage should be 12-14.
Suggest you get at the connections first and clean and tighten. OP switch failure is pretty rare.
interesting note: Some of the buzzers have a separate connection for each alarm function. so be sure that all of the connectors on the buzzer are tight/clean

EDIT: Wet beat me .. posted just before I hit "Send" .. I think info is the same.. Happy hunting

 

[MickP]

Claude and Mr Wetass,
Thanks very much for prompt and useful responses. I will give these a go
Cheers

 

[MickP]

I couldn't disconnect the connector from the sender pin - the screw head had been chewed up. So i looked at the connections, sprayed a bit of WD-40 and wiggled a few wires about and it works. Of course, if it happens again i am none the wiser about which bit it was, but in the mean time i have got my beep back. Thanks guys

 

[kloudie1]

Glad ya got your beep back, Mick.

 

[robertsapp]

Just for future reference, in case anyone else wanders around this thread someday, our oil alarm stopped working as well a while back, and when I troubleshot it, I found that for some unexplained reason, the input to the alarm buzzer had somehow burned out or shorted or something. The buzzer Yanmar used on the panel that came with the 2GM and 3GM has four inputs and a common lead. When I applied 12v to each of the inputs, the alarm would sound except the one the oil sender was attached to. So I priced a new buzzer and quickly found out that they're made of spun gold with diamond and platinum internals. (I think it was over $200 for a stupid $5 part). After thinking about it some more, I realized that one of the four inputs wasn't being used (it was there for a saildrive seal failure alarm, and our boats don't use saildrives) so after a quick trip to Radio Shack to buy a $6 pin extractor tool, I was able to reconfigure the pin-out configuration on the wiring harness where it plugged into the buzzer to send the oil pressure signal to the unused (and still functioning) input. Problem solved!

 

[Ken13559]

Robertsapp, I had same problem as yours...exactly and resolve using the Saildrive circuit. There are 4 diodes, one of each input. One of the diodes got bad/open.