Electrical switch question

[kschitoskey]

I'm going to be installing a pacbrake exhaust brake in my truck soon. I'm looking at switches also, and would like to use a Carling toggle switch to activate it. The schematic for the PRXB shows the activation switch on the ground side. I would like to use a lighted switch, but obviously cannot energize this circuit. Would a DPDT switch work (one side controlling ground only)?



Thanks

 

[jelag]

The pacbrake kit comes with a switch in the box... its not a lighted switch for a specific reason... the switch is wired to be a ground signal to the ECM to turn on the exhaust brake... what is happening is that the ground to the air solenoid goes to the ECM as well... When the ECM calls for the exhaust brake to come on and the switch is ON then the connection between the 2 pins on the ECM is completed and the ground circuit is complete and the brake works... .

PacBrake tested and attempted to use a lighted switch but found that any 12+ that might get applied to the ECM caused problems...

I'm thinking if you understand the DPDT swtich you can make this work, but understand that any 12v + applied to the ECM can damage it... .

Are you aware that there is now a $100 rebate available on your pacbrake purchase... Its there for a limited time...

Do you know Grizzly (George) who is a member here, and lives in Albuquerque?

Hope this helps. .

 

[JMarketos]

If the DPDT idea doesn't work out, here's another possibility-

Use a fog light relay. Use your desired (lighted) toggle switch to activate the coil on the relay (same as a relay circuit is typically configured). That way, your lighted toggle switch is being used to send +12V to the coil side of the relay. Then on the secondary side of the relay, that's just a switch that gets closed by the coil. Connect the secondary side of the relay one terminal to ground, the other terminal to your pacbrake. Then, energizing the coil of the relay with +12V from your switch causes the pac brake wire to become grounded. When the relay is off, the pac brake wire is open circuit (connected to nothing).

 

[kschitoskey]

switch question

Thanks for the replies. I like the appearance of the Carlton switches; but the stakes are high in this instance. Screwing with the ECM is not something I even want to think about. Great idea of using another relay; I wonder what's the danger of current bleeding into that switched circuit?

I haven't met Grizzly yet - but I've enjoyed his posts. ABQ is a small town so I'll run into him some time I'm sure. I see Joe Donnely's truck around from time to time as well.

 

[JMarketos]

A relay is just an electrically controlled switch. The coil side is electrically isolated from the output (switch) side. Only risk of electricity getting from the coil to the switched side is if something went wrong inside the relay, which I'd say is very rare. If you choose to use the relay setup, you can wire it up on the workbench first and energize the coil leads with +12V, and measure the output switch connection with an ohm meter to make sure you've got the connections as you want them. Also you can test the output switch side for +12V to ground, to verify there is no +12V getting into there.