low pressure air alarm not working properly, ADVICE APPRECIATED

They do and both replaced but only the primary sends a signal to dash to activate dash VERY QUIET buzzer. It will not activate the large buzzer i found only switching on the dump switch willnsend full 12v power to buzzer a and lownpressure light below dash

 

You probably have the same dash cluster that I have in my Columbia. The low air warning is a very simple circuit. One single wire out of the cluster, RH connector, cavity B3. The wire, at least on my ‘07, is labled as circuit 18 (printed on the wire) and goes from cavity B3 on the ICU (instrument cluster), to one terminal on the primary air switch.

Then from the other terminal on the primary air switch to a terminal on the secondary air switch, labled as circuit 18a.

And finally, from the second terminal on the secondary air switch, to ground... labled GND.

 

Take a picture of the instrument cluster and post it here. Then remove it and take a picture of the connectors on the back.

 

Yes my wire is 18b only 10.5 volts are produced by it....thats the problem.

 

Ignore the small backfeed voltage on the circuit. Mine has the same thing when it is operating normally.

 

Here's the schematic for my truck. Yours should be similar.

 

Yesterday intapped into that wire and ran to buzzer and lownpressure light under dash. Not enough volts to activate...so i bought a relay which also doesnt wprk

 

Nevermind... the quality got degraded when I uploaded. I'll scan it again and upload it to my web server and you can download it there.

 

THANKS

 

Let me make some coffee and I'll explain how to bypass all the factory wiring and rewire it to work correctly. Sometimes it's faster that way.