Oil and Water Temp Alarms not working

[sjcare]

I replaced my Stbd Water Temp and Oil Gauges on both upper and lower helm recently. I also replaced my oil and water temp senders with dual station senders matched to the Sierra Gauges.

The problem is my lower and upper helm Oil and Water Temp alarms aren't sounding when I turn my ignition on. I've triple check the wiring, the gauges show proper oil pressure and water temp when engine is running. And when I ground the relay where the wire from those alarm switches connect it sounds and the light comes on like it's supposed to. I've checked the resistance on both switches and they're good.

For the life of me I can't figure out what the issue is. The oil sw should be normally closed creating the ground with no oil pressure, and the water is normally open and grounds when the temp is too high. So they should work.

Any help or direction on what to try next would be greatly appreciated it.

 

[Ski in NC]

What engine is it?

 

[sjcare]

Sorry,

Ford Lehman 120s

 

[STB]

Oil pressure starts out in the alarm state -- low oil pressure. So, if it isn't alarming initially, try grounding that wire to the black at the switch. If that alarms the oil switch is likely bad. If not, look for 12v there. If there is a lot less, there is a resistance problem. If nothing, a connectivity problem.

Chase that wire back to the prior switch or relay Try shorting it there and checking for 12v where it comes into the switch. Walk towards that relay until you find the break. You are looking for a bad connector or a high resistance connection. Resistance may add up over a bunch of connections. Look for anywhere there is a voltage drop and clean. I'd leave the pil pressure switch wire grounded while chasing back.

Alternatively, verify voltage on the relay wire. Then follow the relay wire to the 1st switch to the 2nd, and so on. You are doing the same test in reverse, looking for where the voltage stops (break) or drops a lot (high resistance connection).

Happy hunting!