M939 Air pressure switch

[M35A2-AZ]

My low air pressure light and buzzer would intermittently light and sound although the pressure in both tanks read 120psi. I checked the voltage from cab to switch and reads 12 volt. The ground tests good but I still scraped and wire brushed ground boulders and frame and still no luck. I checked voltage across both switches and they are good when truck pressure is good. I even went and replaced both switches with new ones from Erik's, who by the way is very helpful. Now the light and and buzzer went from intermittently to sounding constantly.....driving me crazy. The voltage across the switches is good to the ground. Any thoughts? Your help is greatly appreciated!!!!

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The switches are in series to ground, so if one is bad the alarm will sound. I am thinking your fail safe alarm is bad.

 

[TEAMJENSEN]

The switches are in series to ground, so if one is bad the alarm will sound. I am thinking your fail safe alarm is bad.

Thank you, had not heard of them going. Any idea where to get one of them? I disconnected it, the green plastic box near driver left foot to stop that buzzer.

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[TEAMJENSEN]

Just found on the e bay and at Erik's.

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[M35A2-AZ]

Just found on the e bay and at Erik's.

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Good place to get it or ask here on S/S for a good take out.

 

[TEAMJENSEN]

Anyone here have a good take out fail safe alarm for a m923a2?

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[Amer-team]

Question, my low air pressure light is not coming on, parking brake light is staying on and no alarm sounding even on start up. Gauges read 120 after air up. Thoughts please. This is a 1984 M923 I did wiggle wires to the alarm with no difference and no loose ground.